What is this apple's abnormality?

What is this apple's abnormality?

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The apple pictured is a of the Gala variety,typically striped.The stripes swirl around a brown protrusion. The protrusion is flexible,in the way a leaf is flexible. The flesh underneath is not discolored or soft. The apple is not misshapen,the seeds are not un-developed or underdeveloped. What is this brown protrusion called and what causes it?

I take it that the question is about the mis-shapenness of the apple, that the stick we see in the dip is the core. The morphology (shape) of fruits such as apple and pear are very sensitive to how well the fruit was pollinated. As we know there can be a variable number of seeds in an apple, but the important fact determining shape is that there should be viable seed develop in each of the five seed pockets resulting in balanced development of the fruit. If the pollination is poor and only a few embryo seeds are fertilized, then the development of the surrounding flesh will favour the pockets that contain viable seed, resulting in possibly mis-shapen fruit. Once you have wondered enough and decide to eat, cut open carefully and on the small side you should see that the seeds are either too few, non-existent or failed to develop.

What is this apple's abnormality? - Biology

Galls (from Latin galla, 'oak-apple') or cecidia (from Greek kēkidion, anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths [1] of plant tissues, similar to benign tumors or warts in animals. They can be caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites. Plant galls are often highly organized structures so that the cause of the gall can often be determined without the actual agent being identified. This applies particularly to some insect and mite plant galls. The study of plant galls is known as cecidology.

In human pathology, a gall is a raised sore on the skin, usually caused by chafing or rubbing. [2]


The name amyloid comes from the early mistaken identification by Rudolf Virchow of the substance as starch (amylum in Latin, from Greek ἄμυλον amylon), based on crude iodine-staining techniques. For a period, the scientific community debated whether or not amyloid deposits are fatty deposits or carbohydrate deposits until it was finally found (in 1859) that they are, in fact, deposits of albumoid proteinaceous material. [9]

  • The classical, histopathological definition of amyloid is an extracellular, proteinaceous fibrillar deposit exhibiting β-sheetsecondary structure and identified by apple-green birefringence when stained with congo red under polarized light. These deposits often recruit various sugars and other components such as Serum Amyloid P component, resulting in complex, and sometimes inhomogeneous structures. [10] Recently this definition has come into question as some classic, amyloid species have been observed in distinctly intracellular locations. [11]
  • A more recent, biophysical definition is broader, including any polypeptide that polymerizes to form a cross-β structure, in vivo or in vitro, inside or outside cells. Microbiologists, biochemists, biophysicists, chemists and physicists have largely adopted this definition, [12][13] leading to some conflict in the biological community over an issue of language.

To date, 37 human proteins have been found to form amyloid in pathology and be associated with well-defined diseases. [2] The International Society of Amyloidosis classifies amyloid fibrils and their associated diseases based upon associated proteins (for example ATTR is the group of diseases and associated fibrils formed by TTR). [3] A table is included below.

Protein Diseases Official abbreviation
β amyloid peptide (Aβ) from Amyloid precursor protein [14] [15] [16] [17] Alzheimer's disease, Hereditary cerebral haemorrhage with amyloidosis
α-synuclein [15] Parkinson's disease, Parkinson's disease dementia, Dementia with Lewy bodies, Multiple system atrophy AαSyn
PrP Sc [18] Transmissible spongiform encephalopathy (e.g. Fatal familial insomnia, Gerstmann-Sträussler-Scheinker disease, Creutzfeldt-Jacob disease, New variant Creutzfeldt-Jacob disease) APrP
Microtubule-associated protein tau Various forms of tauopathies (e.g. Pick's disease, Progressive supranuclear palsy, Corticobasal degeneration, Frontotemporal dementia with parkinsonism linked to chromosome 17, Argyrophilic grain disease) ATau
Huntingtin exon 1 [19] [20] Huntington's disease none
ABri peptide Familial British dementia ABri
ADan peptide Familial Danish dementia ADan
Fragments of immunoglobulin light chains [21] Light chain amyloidosis AL
Fragments of immunoglobulin heavy chains [21] Heavy chain amyloidosis AH
full length of N-terminal fragments of Serum amyloid A protein AA amyloidosis AA
Transthyretin Senile systemic amyloidosis, Familial amyloid polyneuropathy, Familial amyloid cardiomyopathy, Leptomeningeal amyloidosis ATTR
Beta-2 microglobulin Dialysis related amyloidosis, Hereditary visceral amyloidosis (familial) Aβ2M
N-terminal fragments of Apolipoprotein AI ApoAI amyloidosis AApoAI
C-terminally extended Apolipoprotein AII ApoAII amyloidosis AApoAII
N-terminal fragments of Apolipoprotein AIV ApoAIV amyloidosis AApoAIV
Apolipoprotein C-II ApoCII amyloidosis AApoCII
Apolipoprotein C-III ApoCIII amyloidosis AApoCIII
fragments of Gelsolin familial amyloidosis, Finnish type AGel
Lysozyme Hereditary non-neuropathic systemic amyloidosis ALys
fragments of Fibrinogen alpha chain Fibrinogen amyloidosis AFib
N-terminally truncated Cystatin C Hereditary cerebral hemorrhage with amyloidosis, Icelandic type ACys
IAPP (Amylin) [22] [23] Diabetes mellitus type 2, Insulinoma AIAPP
Calcitonin [21] Medullary carcinoma of the thyroid ACal
Atrial natriuretic factor Cardiac arrhythmias, Isolated atrial amyloidosis AANF
Prolactin Pituitary Prolactinoma APro
Insulin Injection-localized amyloidosis AIns
Lactadherin / Medin Aortic medial amyloidosis AMed
Lactotransferrin / Lactoferrin Gelatinous drop-like corneal dystrophy ALac
Odontogenic ameloblast-associated protein Calcifying epithelial odontogenic tumors AOAAP
Pulmonary surfactant-associated protein C (SP-C) Pulmonary alveolar proteinosis ASPC
Leukocyte cell-derived chemotaxin-2 (LECT-2) Renal LECT2 amyloidosis ALECT2
Galectin-7 Lichen amyloidosis, Macular amyloidosis AGal7
Corneodesmosin Hypotrichosis simplex of the scalp ACor
C-terminal fragments of TGFBI/Keratoepithelin Lattice corneal dystrophy type I, Lattice corneal dystrophy type 3A, Lattice corneal dystrophy Avellino type AKer
Semenogelin-1 (SGI) Seminal vesicle amyloidosis ASem1
Proteins S100A8/A9 Prostate cancer none
Enfuvirtide Injection-localized amyloidosis AEnf

Many examples of non-pathological amyloid with a well-defined physiological role have been identified in various organisms, including human. These may be termed as functional or physiological or native amyloid. [24] [25] [2]

  • Functional amyloid in Homo sapiens:
    • Intralumenal domain of melanocyte protein PMEL[26]
    • Peptide/protein hormones stored as amyloids within endocrine secretory granules [27]
    • Receptor-interacting serine/threonine-protein kinase 1/3 (RIP1/RIP3) [28]
    • Fragments of prostatic acid phosphatase and semenogelins[29]
    • Functional amyloid in other organisms:
        produced by E. coli,Salmonella, and a few other members of the Enterobacteriales (Csg). The genetic elements (operons) encoding the curli system are phylogenetic widespread and can be found in at least four bacterial phyla. [30] This suggest that many more bacteria may express curli fibrils.
    • GvpA, forming the walls of particular Gas vesicles, i.e. the buoyancy organelles of aquatic archaea and eubacteria [31]
    • Fap fibrils in various species of Pseudomonas[32][33]
    • Chaplins from Streptomyces coelicolor[34] from Trichonephila edulis (spider) (Spider silk) [35] from Neurospora crassa and other fungi [36]
    • Fungal cell adhesion proteins forming cell surface amyloid regions with greatly increased binding strength [37][38]
    • Environmental biofilms according to staining with amyloid specific dyes and antibodies. [39] For example, Bacillus subtilis biofilms involve the TasA protein, which forms functional amyloids maintaining biofilm structure. [40]
    • Tubular sheaths encasing Methanosaeta thermophila filaments [41]
      • Functional amyloid acting as prions
        • Several yeast prions are based on an infectious amyloid, e.g. [PSI+] (Sup35p) [URE3] (Ure2p) [PIN+] or [RNQ+] (Rnq1p) [SWI1+] (Swi1p) and [OCT8+] (Cyc8p)
        • Prion HET-s from Podospora anserina[42]
        • Neuron-specific isoform of CPEB from Aplysia californica (marine snail) [43]

        Amyloids are formed of long unbranched fibers that are characterized by an extended beta-sheet secondary structure in which individual beta strands (β-strands) (coloured arrows in the adjacent figure) are arranged in an orientation perpendicular to the long axis of the fiber. Such a structure is known as cross-β structure. Each individual fiber may be 7–13 nanometres in width and a few micrometres in length. [6] [2] The main hallmarks recognised by different disciplines to classify protein aggregates as amyloid is the presence of a fibrillar morphology with the expected diameter, detected using transmission electron microscopy (TEM) or atomic force microscopy (AFM), the presence of a cross-β secondary structure, determined with circular dichroism, FTIR, solid-state nuclear magnetic resonance (ssNMR), X-ray crystallography, or X-ray fiber diffraction (often considered the "gold-standard" test to see whether a structure contains cross-β fibres), and an ability to stain with specific dyes, such as Congo red, thioflavin T or thioflavin S. [2]

        The term "cross-β" was based on the observation of two sets of diffraction lines, one longitudinal and one transverse, that form a characteristic "cross" pattern. [45] There are two characteristic scattering diffraction signals produced at 4.7 and 10 Ångstroms (0.47 nm and 1.0 nm), corresponding to the interstrand and stacking distances in beta sheets. [1] The "stacks" of beta sheet are short and traverse the breadth of the amyloid fibril the length of the amyloid fibril is built by aligned β-strands. The cross-β pattern is considered a diagnostic hallmark of amyloid structure. [6]

        Amyloid fibrils are generally composed of 1–8 protofilaments (one protofilament also corresponding to a fibril is shown in the figure), each 2–7 nm in diameter, that interact laterally as flat ribbons that maintain the height of 2–7 nm (that of a single protofilament) and are up to 30 nm wide more often protofilaments twist around each other to form the typically 7–13 nm wide fibrils. [2] Each protofilament possesses the typical cross-β structure and may be formed by 1–6 β-sheets (six are shown in the figure) stacked on each other. Each individual protein molecule can contribute one to several β-strands in each protofilament and the strands can be arranged in antiparallel β-sheets, but more often in parallel β-sheets. Only a fraction of the polypeptide chain is in a β-strand conformation in the fibrils, the remainder forms structured or unstructured loops or tails.

        For a long time our knowledge of the atomic-level structure of amyloid fibrils was limited by the fact that they are unsuitable for the most traditional methods for studying protein structures. Recent years have seen progress in experimental methods, including solid-state NMR spectroscopy and Cryo-Electron Microscopy. Combined, these methods have provided 3D atomic structures of amyloid fibrils formed by amyloid β peptides, α-synuclein, tau, and the FUS protein, associated with various neurodegenerative diseases. [46] [47]

        X-ray diffraction studies of microcrystals revealed atomistic details of core region of amyloid, although only for simplified peptides having a length remarkably shorter than that of peptides or proteins involved in disease. [48] [49] The crystallographic structures show that short stretches from amyloid-prone regions of amyloidogenic proteins run perpendicular to the filament axis, consistent with the "cross-β" feature of amyloid structure. They also reveal a number of characteristics of amyloid structures – neighboring β-sheets are tightly packed together via an interface devoid of water (therefore referred to as dry interface), with the opposing β-strands slightly offset from each other such that their side-chains interdigitate. This compact dehydrated interface created was termed a steric-zipper interface. [6] There are eight theoretical classes of steric-zipper interfaces, dictated by the directionality of the β-sheets (parallel and anti-parallel) and symmetry between adjacent β-sheets. A limitation of X-ray crystallography for solving amyloid structure is represented by the need to form microcrystals, which can be achieved only with peptides shorter than those associated with disease.

        Although bona fide amyloid structures always are based on intermolecular β-sheets, different types of "higher order" tertiary folds have been observed or proposed. The β-sheets may form a β-sandwich, or a β-solenoid which may be either β-helix or β-roll. Native-like amyloid fibrils in which native β-sheet containing proteins maintain their native-like structure in the fibrils have also been proposed. [50]

        One complicating factor in studies of amyloidogenic polypeptides is that identical polypeptides can fold into multiple distinct amyloid conformations. [6] This phenomenon is typically described as amyloid polymorphism. [8] [51] [52] It has notable biological consequences given that it is thought to explain the prion strain phenomenon.

        Amyloid is formed through the polymerization of hundreds to thousands of monomeric peptides or proteins into long fibers. Amyloid formation involves a lag phase (also called nucleation phase), an exponential phase (also called growth phase) and a plateau phase (also called saturation phase), as shown in the figure. [53] [54] [55] [56] Indeed, when the quantity of fibrils is plotted versus time, a sigmoidal time course is observed reflecting the three distinct phases.

        In the simplest model of 'nucleated polymerization' (marked by red arrows in the figure below), individual unfolded or partially unfolded polypeptide chains (monomers) convert into a nucleus (monomer or oligomer) via a thermodynamically unfavourable process that occurs early in the lag phase. [55] Fibrils grow subsequently from these nuclei through the addition of monomers in the exponential phase. [55]

        A different model, called 'nucleated conformational conversion' and marked by blue arrows in the figure below, was introduced later on to fit some experimental observations: monomers have often been found to convert rapidly into misfolded and highly disorganized oligomers distinct from nuclei. [57] Only later on, will these aggregates reorganise structurally into nuclei, on which other disorganised oligomers will add and reorganise through a templating or induced-fit mechanism (this 'nucleated conformational conversion' model), eventually forming fibrils. [57]

        Normally folded proteins have to unfold partially before aggregation can take place through one of these mechanisms. [58] In some cases, however, folded proteins can aggregate without crossing the major energy barrier for unfolding, by populating native-like conformations as a consequence of thermal fluctuations, ligand release or local unfolding occurring in particular circumstances. [58] In these native-like conformations, segments that are normally buried or structured in the fully folded and possessing a high propensity to aggregate become exposed to the solvent or flexible, allowing the formation of native-like aggregates, which convert subsequently into nuclei and fibrils. This process is called 'native-like aggregation' (green arrows in the figure) and is similar to the 'nucleated conformational conversion' model.

        A more recent, modern and thorough model of amyloid fibril formation involves the intervention of secondary events, such as 'fragmentation', in which a fibril breaks into two or more shorter fibrils, and 'secondary nucleation', in which fibril surfaces (not fibril ends) catalyze the formation of new nuclei. [56] Both secondary events increase the number of fibril ends able to recruit new monomers or oligomers, therefore accelerating fibril formation. These events add to the well recognised steps of primary nucleation (formation of the nucleus from the mnonomers through one of models described above), fibril elongation (addition of monomers or oligomers to growing fibril ends) and dissociation (opposite process).

        Such a new model is described in the figure on the right and involves the utilization of a 'master equation' that includes all steps of amyloid fibril formation, i.e. primary nucleation, fibril elongation, secondary nucleation and fibril fragmentation. [56] The rate constants of the various steps can be determined from a global fit of a number of time courses of aggregation (for example ThT fluorescence emission versus time) recorded at different protein concentrations. [56]

        Following this analytical approach, it has become apparent that the lag phase does not correspond necessarily to only nucleus formation, but rather results from a combination of various steps. Similarly, the exponential phase is not only fibril elongation, but results from a combination of various steps, involving primary nucleation, fibril elongation, but also secondary events. A significant quantity of fibrils resulting from primary nucleation and fibril elongation may be formed during the lag phase and secondary steps, rather than only fibril elongation, can be the dominant processes contributing to fibril growth during the exponential phase. With this new model, any perturbing agents of amyloid fibril formation, such as putative drugs, metabolites, mutations, chaperones, etc., can be assigned to a specific step of fibril formation.

        In general, amyloid polymerization (aggregation or non-covalent polymerization) is sequence-sensitive, that is mutations in the sequence can induce or prevent self-assembly. [59] [60] For example, humans produce amylin, an amyloidogenic peptide associated with type II diabetes, but in rats and mice prolines are substituted in critical locations and amyloidogenesis does not occur. [ citation needed ] Studies comparing synthetic to recombinant β amyloid peptide in assays measuring rate of fibrillation, fibril homogeneity, and cellular toxicity showed that recombinant β amyloid peptide has a faster fibrillation rate and greater toxicity than synthetic β amyloid peptide. [61]

        There are multiple classes of amyloid-forming polypeptide sequences. [8] [51] [52] Glutamine-rich polypeptides are important in the amyloidogenesis of Yeast and mammalian prions, as well as Trinucleotide repeat disorders including Huntington's disease. When glutamine-rich polypeptides are in a β-sheet conformation, glutamines can brace the structure by forming inter-strand hydrogen bonding between its amide carbonyls and nitrogens of both the backbone and side chains. The onset age for Huntington's disease shows an inverse correlation with the length of the polyglutamine sequence, with analogous findings in a C. elegans model system with engineered polyglutamine peptides. [62]

        Other polypeptides and proteins such as amylin and the β amyloid peptide do not have a simple consensus sequence and are thought to aggregate through the sequence segments enriched with hydrophobic residues, or residues with high propensity to form β-sheet structure. [59] Among the hydrophobic residues, aromatic amino-acids are found to have the highest amyloidogenic propensity. [63] [64]

        Cross-polymerization (fibrils of one polypeptide sequence causing other fibrils of another sequence to form) is observed in vitro and possibly in vivo. This phenomenon is important, since it would explain interspecies prion propagation and differential rates of prion propagation, as well as a statistical link between Alzheimer's and type 2 diabetes. [65] In general, the more similar the peptide sequence the more efficient cross-polymerization is, though entirely dissimilar sequences can cross-polymerize and highly similar sequences can even be "blockers" that prevent polymerization. [ citation needed ]

        The reasons why amyloid cause diseases are unclear. In some cases, the deposits physically disrupt tissue architecture, suggesting disruption of function by some bulk process. An emerging consensus implicates prefibrillar intermediates, rather than mature amyloid fibers, in causing cell death, particularly in neurodegenerative diseases. [16] [66] The fibrils are, however, far from innocuous, as they keep the protein homeostasis network engaged, release oligomers, cause the formation of toxic oligomers via secondary nucleation, grow indefinitely spreading from district to district [2] and, in some cases, may be toxic themselves. [67]

        Calcium dysregulation has been observed to occur early in cells exposed to protein oligomers. These small aggregates can form ion channels through lipid bilayer membranes and activate NMDA and AMPA receptors. Channel formation has been hypothesized to account for calcium dysregulation and mitochondrial dysfunction by allowing indiscriminate leakage of ions across cell membranes. [68] Studies have shown that amyloid deposition is associated with mitochondrial dysfunction and a resulting generation of reactive oxygen species (ROS), which can initiate a signalling pathway leading to apoptosis. [69] There are reports that indicate amyloid polymers (such as those of huntingtin, associated with Huntington's disease) can induce the polymerization of essential amyloidogenic proteins, which should be deleterious to cells. Also, interaction partners of these essential proteins can also be sequestered. [70]

        All these mechanisms of toxicity are likely to play a role. In fact, the aggregation of a protein generates a variety of aggregates, all of which are likely to be toxic to some degree. A wide variety of biochemical, physiological and cytological perturbations has been identified following the exposure of cells and animals to such species, independently of their identity. The oligomers have also been reported to interact with a variety of molecular targets. Hence, it is unlikely that there is a unique mechanism of toxicity or a unique cascade of cellular events. The misfolded nature of protein aggregates causes a multitude of aberrant interactions with a multitude of cellular components, including membranes, protein receptors, soluble proteins, RNAs, small metabolites, etc.

        In the clinical setting, amyloid diseases are typically identified by a change in the spectroscopic properties of planar aromatic dyes such as thioflavin T, congo red or NIAD-4. [71] In general, this is attributed to the environmental change, as these dyes intercalate between beta-strands to confine their structure. [72]

        Congo Red positivity remains the gold standard for diagnosis of amyloidosis. In general, binding of Congo Red to amyloid plaques produces a typical apple-green birefringence when viewed under cross-polarized light. Recently, significant enhancement of fluorescence quantum yield of NIAD-4 was exploited to super-resolution fluorescence imaging of amyloid fibrils [73] and oligomers. [74] To avoid nonspecific staining, other histology stains, such as the hematoxylin and eosin stain, are used to quench the dyes' activity in other places such as the nucleus, where the dye might bind. Modern antibody technology and immunohistochemistry has made specific staining easier, but often this can cause trouble because epitopes can be concealed in the amyloid fold in general, an amyloid protein structure is a different conformation from the one that the antibody recognizes.

        The following video(s) are recommended for use in association with this case study.

          This lighthearted video takes a look at the individual organs of the digestive system, how food is digested into usable nutrients, and how those nutrients are mobilized to different parts of the body. Running time: 14:05 min. Created by Jennifer Jackson and Karen Aguirre for the National Center for Case Study Teaching in Science, 2017.
          This brief animation from the Mayo Clinic describes the Roux-en-Y gastric bypass procedure. Running time: 0:48 min. Produced by the Mayo Clinic, 2012.
          This claymation video introduces a camper who drinks water contaminated with Vibrio cholera, and describes the mechanism of action of cholera toxin. The toxin disrupts the function of the chloride transport system in the small intestine, resulting in abnormal water partition in the small bowel, with life-threatening excretion of fluid in the form of rice-water-stool. Running time: 2:04 min. Produced by the “Clay mators,” 2012.

        A game-changing discovery

        The discovery of a hidden reservoir of malaria parasites in the spleen was a "game changer", said Justin Boddey of the Walter and Eliza Hall Institute.

        "We always think we understand everything, then something like this comes along and it's completely not what one would expect."

        Dr Boddey, who was not involved in this research, studies the malaria parasite particularly in liver cells, which provide a hiding place for the first stage of the parasites before they enter blood cells and cause disease.

        "[This new work] explains now there are two reservoirs. Not just the first phase of infection in the liver, but there's this other reservoir in the spleen after the parasites come out of the liver," he said.

        "This whole lifecycle [of the parasite] they are describing has been missed."

        In particular, Dr Boddey said, the finding that the spleen contained blood cells with active parasites still growing normally was striking.

        "That shows if they are viable, they can come out again, so there's a possibility for reseeding an infection that makes someone feel sick, but also to transmit it onward."

        Testing for Chronic Diarrhea Testing for Fructose Intolerance

        Fructose is found in modern diets and is frequently used as a sweetener in a variety of food items. The normal absorption of capacity of fructose is poorly understood, but it has been established that the absorptive capacity for fructose that is not accompanied by glucose is relatively small [131] . Incomplete fructose absorption, as a cause for osmotic diarrhea, is identified by a positive result on a breath hydrogen test following ingestion of 25–50 g of fructose. In one large study, patients with symptomatic moderate fructose malabsorption who had a positive test using a 50-g fructose load were asked to undergo a fructose breath test with 25 g of fructose. Those patients with a positive test using 25 g were considered severe fructose malabsorbers. This may have clinical relevance as it remains to be investigated whether these patients would benefit from a stricter dietary management of symptoms. Recent work has showcased findings that symptom induction and improvement was not simply and directly related to the presence of a positive hydrogen breath test after fructose ingestion [132] . Symptoms arising from fructose ingestion may be generated from osmotically induced distention of the small intestine, even in the absence of fermentation. As such, these observations imply that breath testing demonstration of fructose malabsorption has little clinical predictive value, and a therapeutic trial of fructose restriction may be valuable in discerning etiology for chronic diarrhea particularly in high consumers of fructose-containing food and beverages.

        The placenta is the site of nutrient, gas exchange, and excretion between the fetus and mother. Placentas are a defining characteristic of placental mammals but they are found in marsupials and some non-mammals with varying levels of development.

        Development of the placenta

        At first, the chorionic villi cover the entire surface of the chorion. Later on, the villi opposite the decidua basalis continue to grow and expand to form chorion frondosum. While the villi related to the decidua capsularis degenerate and this part of chorion called chorion leave. The placenta is formed by:

        • Mainly by the chorion frondosum (the fetal part, chorionic plate).
        • A small extent by the decidua basalis (the maternal part, decidual plate).

        Structure of the placenta

        • Formation of the placenta started at the 4 th month.
        • The placenta has two components: the fetal part (chorion frondosum) and the maternal part (decidua basalis).
        • Spaces between the villi appear and fuse together forming the intervillous spaces. They are filled with maternal blood. This blood leaked from the spiral arteries eroded by fetal chorionic villi.
        • Later on, a number of decidual septae attached to the decidual plate are formed.
        • These septa project into the intervillous spaces, but do not reach the chorionic plate, so it is an incomplete septum.
        • As a result of these septa, the maternal surface of the placenta is divided into compartments each one is called “cotyledon”.
        • The intervillous spaces in all the cotyledons are communicating with each other. As pregnancy advances, the placenta increases in size by the formation of new villi, and in thickness due to the extensive arborization (branching) of the villi.

        Gross appearance of full-Term Placenta

        It is discoid shaped with a diameter of 15-25 cm, 3 cm thickness, and a weight of 500-600 gm (about 1/6 of the weight of a full-term fetus). It covers 15-30 % of the decidua. It is delivered approximately 30 minutes after the birth of the baby. It has two surfaces:

        1. Maternal surfaces are irregular, rough, reddish, and contains 15-20 cotyledons with deep grooves in between made by the decidual septa.
        2. The fetal surface is smooth and shiny (as it is covered by amnion). It has a number of chorionic umbilical vessels converging towards the umbilical cord, and the umbilical cord is attached centrally to this surface.

        The placenta membrane (placental barrier)

        It is the structures that separate the maternal and fetal blood. It is not a true barrier because few substances are able to cross it, most drugs in maternal blood can pass through it to the fetal circulation. Some of which can harm the fetus and cause major congenital anomalies. Early in pregnancy (till about 20-week gestation), the placental barrier is formed of four layers:

        • The endothelial lining the fetal vessels.
        • The connective tissue (primary mesoderm) of the villus.
        • The cytotrophoblast layer.
        • The syncytiotrophoblast.

        After 20 weeks the cytotrophoblast degenerate so increases the permeability of the placenta, Towards the end of pregnancy, the fibrinoid material made of fibrin is formed on the surface of the villi to decrease the permeability, so the placental barrier is formed of this fibrinoid material, primary mesoderm, the syncytiotrophoblasts, and the endothelium of the fetal blood vessels.

        The fetal circulation and maternal circulation are closed circulations, meaning that maternal blood and fetal blood do not mix.

        Functions of the placenta

        1. Exchange of gases (respiration): Oxygen, and carbon dioxide are transported by simple diffusion.
        2. Exchange of nutrients, water, and electrolytes (nutrition): as amino acids, fatty acids, carbohydrates, and vitamins.
        3. Transmission of maternal antibodies to the fetus resulting in passive immunity.
        4. Excretion as fetal waste products e.g. urea and uric acid pass through it from fetal to maternal blood.
        5. Selective barrier (protection) against the transmission of diseases from the mother to the fetus. However many maternal infectious agents as viruses of rubella, measles, cytomegalovirus, and toxoplasma can cross the placenta causing severe congenital malformations or fetal death.
        6. Hormone production: By the end of the 4 th month, the placenta secretes the following hormones by the syncytiotrophoblasts:
        • Progesterone (it maintains the corpus luteum and preventing menses during pregnancy).
        • Estrogenic (estriol) hormones.
        • Gonadotrophins: as human chorionic gonadotropins (HCG), somato-mammotropin, human chorionic thyrotropin, and human chorionic corticotropin.
        • Relaxin hormone to soften the ligaments of the pelvis in preparation for the birth of the fetus.

        Abnormalities of the placenta

        1. Shape abnormalities:

        • Bilobed, trilobed, or horseshoe.
        • Placenta membranacea (diffuse placenta), the thin layer of the placenta attaches to a large area of the uterus.

        2. Number abnormalities:

        • Double placentae.
        • Triple placentae.
        • Accessory placenta. It may cause severe postpartum hemorrhage if it is retained in the uterus after labor.

        3. position abnormalities: Placenta previa where the placenta is attached to the lower uterine segment (due to low level of implantation of the blastocyst). It causes severe antepartum hemorrhage. There are three types of placenta previa:

        • Placenta previa centralis: the center of the placenta covers the internal os of the cervix of the uterus.
        • Placenta previa marginalis covers the internal os incompletely.
        • Placenta previa parietalis is attached to the lower segment away from the internal os.

        Placenta previa is usually diagnosed by ultrasonography during pregnancy and delivery must be by Cesarean section to avoid severe antepartum hemorrhage.

        4. Abnormal penetration to the uterine wall:

        • Placenta accreta: due to abnormal adhesion between the chorionic villi and the uterine wall due to excessive penetration of the endometrium.
        • Placenta percreta: The chorionic villi penetrate the myometrium all the way to the perimetrium (uterine peritoneal covering).

        In these two abnormalities, the placenta fails to separate from the uterus after the birth of the fetus and may cause severe postpartum hemorrhage.

        5. Abnormalities due to the attachment of the umbilical cord:

        Functions of the Thyroid

        Like all endocrine glands, the function of the thyroid is to synthesize hormones and secrete them into the bloodstream. Once in the blood, they can travel to cells throughout the body and influence their functions.

        Thyroid Hormones: T4 and T3

        There are two main thyroid hormones produced by the follicles: thyroxine (T4), which contains four iodide ions and is represented by the structural diagram below and triiodothyronine (T3), which contains three iodide ions. T3 is much more powerful than T4, but T4 makes up about 90 percent of circulating thyroid hormone, and T3 makes up only about 10 percent. However, most of the T4 is converted to T3 by target tissues.

        Figure (PageIndex<3>): This structural model represents a single molecule of triiodothyronine (T3) and thyroxine (T4). The letter I represents the iodide ions they contain. The rings consist mainly of carbon atoms

        Figure (PageIndex<4>): The thyroid system is a negative feedback loop that includes the hypothalamus, pituitary gland, and thyroid gland. As this diagram shows, thyroid hormones increase the effect of catecholamines such as adrenaline, a fight-or-flight hormone

        Like steroid hormones, T3 and T4 cross cell membranes everywhere in the body and bind to intracellular receptors to regulate gene expression. However, unlike steroid hormones, thyroid hormones can cross cell membranes only with the help of special transporter proteins. Once inside the nucleus of cells, T3 and T4 turn on genes that control protein synthesis. Thyroid hormones increase the rate of metabolism in cells, so cells absorb more carbohydrates, use more energy, and produce more heat. Thyroid hormones also increase the rate and force of the heartbeat. In addition, they increase the sensitivity of cells to fight-or-flight hormones (that is, catecholamine hormones such as adrenaline).

        The production of both T4 and T3 is regulated primarily by thyroid stimulating hormone (TSH), which is secreted by the anterior pituitary gland (see the diagram below). TSH production, in turn, is regulated by thyrotropin releasing hormone (TRH), which is produced by the hypothalamus. The thyroid gland, pituitary gland, and hypothalamus form a negative feedback loop to keep thyroid hormone secretion within a normal range. TRH and TSH production is suppressed when T4 levels start to become too high. The opposite occurs when T4 levels start to become too low.


        The calcitonin produced by the parafollicular cells of the thyroid gland has the role of helping to regulate blood calcium levels by stimulating the movement of calcium into bone. Calcitonin is secreted in response to rising blood calcium levels. It decreases blood calcium levels by enhancing calcium absorption and deposition in bone. Calcitonin works hand-in-hand with parathyroid hormone, which is secreted by the parathyroid glands and has the opposite effects as calcitonin. Together, these two hormones maintain calcium homeostasis.

        Structure of Apple Snail (Pila) | Zoology

        In this article we will discuss about the structure of Apple Snail (Pila) with the help of a diagram.

        1. It is commonly called “apple snail” and is found in fresh water ponds, pools and ditches in India and adjacent regions.

        2. Shell is external and spirally coiled and is comprised of 6 whorls.

        3. The axis around which coiling takes place is known as columella, the top whorl is known as apical whorl and the large and ultimate whorl is known as animal chamber.

        4. The animal chamber is covered over by operculum.

        5. Along the animal chamber runs a vertical groove the varix, which connects the penultimate whorl and inner lip of mouth.

        6. The animal comprises a head, foot and a visceral mass.

        7. Foot is muscular, flat and serves for creeping.

        8. Visceral mass consists of main body organs and is spirally coiled.

        9. Kidney and ctenidium (gill) unpaired.

        10. A part of mantle is modified into pulmonary sac and serves for aerial respiration. The other mode of respiration being aquatic.

        Apple mealiness detection using hyperspectral scattering technique ☆

        Mealiness is a symptom of fruit physiological disorder, which is characterized by abnormal softness and lack of free juice in the fruit. This research investigated the potential of hyperspectral scattering technique for detecting mealy apples. Spectral scattering profiles between 600 and 1000 nm were acquired, using a hyperspectral imaging system, for ‘Red Delicious’ apples that either had been kept in refrigerated air at 4 °C or undergone mealiness treatment at 20 °C and 95% relative humidity for various time periods of 0–5 weeks. The spectral scattering profiles at individual wavelengths were quantified by relative mean reflectance for 10 mm scattering distance for the test apples. The mealiness of the apples was determined by the hardness and juiciness measurements from destructive confined compression tests. Prediction models for hardness and juiciness were developed using partial least squares regression (PLS) they had low correlation with the destructive measurement (r ≤ 0.76 for hardness and r ≤ 0.54 for juiciness). Moreover, PLS discriminant models were built for two-class (‘mealy’ and ‘nonmealy’), three-class (‘mealy’, ‘semi-mealy’ and ‘fresh’) and four-class (‘mealy’, ‘soft’, ‘dry’, and ‘fresh’) classification. The overall classification accuracies for the two classes of ‘nonmealy’ and ‘mealy’ apples were between 74.6% and 86.7%, while the overall accuracies in the three-class classification ranged between 60.2% and 71.2%. Much better results (≥93% accuracy) were achieved for the two-class classification of ‘mealy’ apples that had undergone longer time of mealiness treatment (i.e., 4–5 weeks of storage at 20 °C and 95% relative humidity). Hyperspectral scattering technique is potentially useful for nondestructive detection of apple mealiness however, improvements in classification accuracy are needed.

        Toriello-Carey syndrome

        The specific features and severity associated with Toriello-Carey syndrome varies among affected people. In 2003, Toriello et al. published a review article in which they reported the features of 45 individuals with TCS. In that review, it was found that most children had normal weight, length, and head circumference at birth, but subsequently developed growth failure and microcephaly . Not all had neonatal problems, but those who did most commonly had respiratory distress or feeding and swallowing difficulties. All had some degree of developmental delay or intellectual disability . [2] [3]

        • telecanthus (increased distance between the inner corners of the eyes) or widely-spaced eyes coupled with short palpebral fissures
        • short/sparse eyelashes
        • short or small nose
        • variable combinations of micrognathia and cleft palate or highly-arched palate (with many children having Pierre Robin sequence)
        • full cheeks
        • abnormal ear shape or position
        • low muscle tone ( hypotonia )
        • abnormal or absent corpus callosum
        • heart anomalies (usually atrial and/or ventricular septal defects, or a patent ductus arteriosus)
        • minor genital anomalies in males
        • short neck

        This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.


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