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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 158 (1975), S. 451-459 
    ISSN: 1432-0878
    Keywords: Pineal nerve ; Sheep and rabbit fetuses ; Subcommissuralorgan ; Ontogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The presence of a nerve located just caudal to the pineal gland in the mid-sagittal plane is demonstrated in sheep and rabbit fetuses. This nerve lies freely in the subarachnoid space and extends from the pineal gland to a region of the CNS located dorsal to the rostralmost part of the subcommissural organ (SCO). In rabbit fetuses the nerve is observed on days 23 and 24 of gestation; we suggest that it is an ontogenetic equivalent to the pineal nerve of anuran amphibians. The developmental fate of the mammalian fetal pineal nerve is discussed.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 159 (1975), S. 195-204 
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Neurons ; Development ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neurons which initially lie in the basal region of the subcommissural organ (SCO) were investigated in 20 rabbit fetuses from day 15 to 30 of gestation, and in eight neonatal, 4 and 8 day old rabbits. These SCO-associated neurons, first observed on day 17 of gestation, develop into (1) a rostral mesodiencephalic nerve cell group situated in an area dorsal to the rostral-most part of the SCO and (2) a more caudal layer of single neurons extending throughout the length of the SCO. The present findings are discussed in relation to recent histochemical studies that demonstrated AChE-positive neurons in the pineal complex and subcommissural area of frogs and to recent fluorescence microscopic studies in fetal and adult rats in which a 5-HT system is known to extend from the nucleus raphe dorsalis (B7) along the SCO to the pineal stalk and habenular region. The term “SCO-associated neurons” is a purely morphological way of describing the neurons in question as the neural interconnections of these neurons are still a matter of speculation.
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  • 3
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Tissue distribution and developmental expression of fetuin were studied in the sheep fetus from embryonic day (E) 30 to adult (gestational period is 150 days). The presence of fetuin was demonstrated immunocytochemically using anti-fetuin antibodies; in situ hybridisation using short anti-sense oligonucleotide probes labelled with digoxigenin was used to study the ability of the developing tissue to synthesise fetuin, and reverse transcription-polymerase chain reaction (RT-PCR) was used to estimate the level of fetuin mRNA in selected tissues. Tissue distribution of fetuin was widespread in the younger fetuses (E30 to E40). The most prominent presence due to in situ synthesis was demonstrated in the liver, central nervous system (CNS) including anterior horn cells, dorsal root ganglia and in skeletal muscle cells. Other developing tissues and organs that showed evidence of fetuin synthesis and presence of the protein included mesenchyme, kidney, adrenal, developing bone, gut, lung and heart. In the immature liver (E30–40) there was a strong signal for fetuin mRNA in hepatocytes and also in numerous haemopoietic cells; the proportion of these latter cells that was positive for fetuin mRNA increased between E30 and E40. Only some hepatocytes and a proportion of the haemopoietic stem cells were immunoreactive for fetuin itself at E30–40; immunoreactive hepatocytes were more frequently observed in the more mature outer regions of the developing liver. Lung and gut contained scattered fetuin-positive epithelial cells, especially at E30; a weak fetuin mRNA signal could be detected above background in many of these cells up to E40, but not at E60–E115 or in the adult. Particularly at E30 to E40, mesenchymal tissue both within organs such as the gut and lung and around forming bone and skeletal muscle contained cells that were positive for fetuin mRNA. Mesenchyme at these ages was also very strongly stained for fetuin protein, much of which may reflect fetuin in tissue extracellular spaces and be derived from the high concentration in plasma. By E80 fetuin mRNA was mainly present in the liver and the CNS; staining of the muscle tissue was becoming less pronounced. However in developing bone tissue, staining of chondrocytes for fetuin mRNA was still prominent in older (E80) fetuses; there was also fetuin protein staining of chondrocytes at the growing surfaces of bones and in bone marrow at this age. In the adult, weak immunocytochemical staining for fetuin itself was present in hepatocytes, but the mRNA signal was barely above the threshold limit of detection. Other tissues in the adult were generally negative for both fetuin mRNA and fetuin, except that fetuin could generally be detected immunocytochemically in precipitated plasma within vessels in many tissues and in their interstitial spaces. The highest levels of fetuin mRNA, as demonstrated by RT-PCR, were detected in E40 and E60 liver followed by E40 muscle. The very low level of fetuin mRNA in adult liver, evident from in situ hybridisation, was confirmed by RT-PCR (about 0.1% of that at E60). These results show that in many tissues in which fetuin could be demonstrated immunocytochemically, its presence is likely to be due to synthesis in situ. However in some instances (e.g. gut and mesenchymal tissue) fetuin probably originates predominantly by uptake from plasma or extracellular fluid. The functional significance of the presence of fetuin in different tissues during their development is considered.
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  • 4
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The specificity of Alcian blue staining has been investigated on a material comprising the adenohypophysis from 26 human foetuses. Two distinct types of alcianophilic cells were observed. The first cell type appears about 28 mm CRL forming small groups at the epithelial-mesenchymal junction and beneath the anlage of the fibrous capsule. Besides its alcianophilic property the cell shows a pronounced maltase-resistant PAS-positivity. The alcianophilia is due to carboxylgroups — probably of proteins as no sialic acid could be detected. By the performic acid — Alcian blue method the cell seems to show a high content of SH and S-S groups. The second type of cell appears about 70 mm CRL and is mostly located singly. It shows a pronounced alcianophilia — probably due to sulphate groups and to some extent to carboxyl groups. The role of the alcianophilic properties of the cells in typing definite cells of the foetal adenohypophysis was discussed. — Finally the pitfalls caused by different fixatives and by the use of the general polychrome staining methods for the typing of pituitary parenchymal cells were discussed.
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  • 5
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract An immunohistochemical study was undertaken, in an attempt to identify the acidic glycoprotein(s) present in colloid and in parenchymal cells in human fetal pituitary gland. As the colloid has been proposed to represent disintegrating cells, a series of antibodies against plasma glycoproteins and plasma proteins was applied; their presence intracellularly would generally be an indicator of plasma membrane leakage in dying parenchymal cells. In tissue sections from 9- to 20-week-old fetuses, the colloid showed prominent staining with an antibody to human fetuin/α2 HS glycoprotein. Anti-α2-HS glycoprotein labelled parenchymal cells in pars anterior and intermedia. Apart from a minor immunoreactivity for α1 β glycoprotein, no other plasma glycoprotein was seen in colloid or parenchymal cells. An antibody against bovine fetuin showed staining of the colloid and of some parenchymal cells in pars distalis and intermedia; the plasma and stroma of the pituitary gland were unstained. In contrast, the anti-human plasma protein antibodies all stained the stroma. The presence of α2 HS glycoprotein in parenchymal cells and absence of other plasma glycoproteins imply integrity of the parenchymal cell plasma membrane. Thus, α2 HS glycoprotein is either synthesized locally or taken up specifically in the parenchymal cells, which are proposed to participate in the formation of colloid. It is suggested that α2 HS glycoprotein is part of a homeostatic system, which controls remodelling and physiological cell death during development.
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  • 6
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A histochemical and ultrastructural study was carried out on subcommissura organs from 42 human embryos and fetuses in order to characterize some “large granules” Typical “granules” make their appearance in the rostral hypendymal region of the subcommissural organ (SCO) in fetuses of about 50 mm CRL. Although they appear in other SCO-regions later, the highest number of “granules” is always located towards the pineal gland. Typical “granules” are of spherical shape with a diameter of about 2 microns. The various histochemical reactions reveal a reactivity which differentiates the shell of the “granules” from the “granule” interior. Nucleoproteins are present in the shell together with phospholipids and/or lipoproteins. The interior of the “granules” can contain different materials such as glycogen or lipid or “neurosecretory substance”. Ultrastructural observations show that a “granule” consists of whorls of endoplasmic reticulum sparsely studded with ribosomes surrounding an interior containing either lipid or lipoprotein inclusions, large amounts of glycogen or simply cytoplasm. It is suggested that the concentric lamellar organelle (CLO) is a morphological entity that might be involved in secretory processes rather than being the secretory granules themselves.
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  • 7
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A technique is described for enhancing the reaction product of the staining reaction for iron in paraffin-embedded tissue from central nervous system (CNS). After amplification of the Prussian Blue staining reaction with 3,3′-diaminobenzidine (DAB), the reaction product was further intensified using a stepwise treatment with silver methenamine, gold chloride and uranyl nitrate (post-DAB treatment). Following the Prussian Blue-DAB staining reaction, iron was seen only in glial cells and choroid plexus epithelial cells, whereas the post-DAB treatment revealed that neurons and endothelial cells of the brain capillaries were also positively stained. The post-DAB treatment resulted additionally in an increased intensity of the reaction product within choroid plexus epithelial cells compared to that obtained in sections subjected only to the Prussian Blue-DAB reaction. The reliability of the method was evaluated using liver sections as positive controls. Furthermore the higher sensitivity of the method was assessed using nitrocellulose filters containing serially diluted iron-saturated transferrin. The post-DAB method is simple and can easily be applied to formalin- or glutaraldehyde fixed, paraffin-embedded nervous and non-nervous tissue.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 146 (1973), S. 69-81 
    ISSN: 1432-0878
    Keywords: Human enamel organ ; Ameloblasts ; Cell junctions ; Tooth development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The nature and distribution of cell contacts have been examined in the human enamel organ in bell stage. The lateral cell surfaces of secretory ameloblasts are linked at their distal (apical) and proximal (basal) parts by junctional complexes consisting of tight junctions, large intermediate junctions (zonulae adherentes), occasional gap junctions and one or more series of desmosomes. Scattered desmosomes and large gap junctions link epithelial cells of the external enamel epithelium, stellate reticulum, stratum intermedium and internal enamel epithelium including secretory ameloblasts. Furthermore the above-mentioned layers are also linked together by desmosomes and gap junctions. With increasing maturation of the enamel organ an increase in size and number of gap junctions is observed. Some possible implications of the role of the different junctions are considered. The gap junctions probably participate in cell differentiation in the normal morphogenesis of the teeth as well as in metabolic and ionic coupling of the cells of the enamel organ. By means of tight junctions, adjacent secretory ameloblasts cooperate to form a physical barrier which might prevent the diffusion of some types of molecules or substances (e.g. secretory material distally and acid mucopolysaccharides proximally) through the interspaces between the cells. Adhering junctions might assist in regulation of the mechanical properties of the enamel organ as a whole.
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  • 9
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Ependyma ; Astrocytes ; Immunocytochemistry ; Glial fibrillary acidic (GFA) protein ; S-100 protein ; Glutamine synthetase ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Antibodies raised against glial fibrillary acidic protein (GFA), S-100 protein (S100) and glutamine synthetase (GS) are currently used as glial markers. The distribution of GFA, S100 and GS in the ependyma of the rat subcommissural organ (SCO), as well as in the adjacent nonspecialized ventricular ependyma and neuropil of the periaqueductal grey matter, was studied by use of the immunocytochemical peroxidase-antiperoxidase technique. In the neuropil, GFA, S100 and GS were found in glial elements, i.e., in fibrous (GFA, S100) and protoplasmic astrocytes (S100, GS). The presence of S100 in the majority of the ventricular ependymal cells and tanycytes, and the presence of GFA in a limited number of ventricular ependymal cells and tanycytes confirm the glial nature of these cells. The absence of S100, GFA and GS from the ependymocytes of the SCO, which are considered to be modified ependymal cells, suggests either a non-astrocytic lineage of these cells or an extreme specialization of the SCO-cells as glycoprotein-synthesizing and secreting elements, a process that may have led to the disappearance of the glial markers.
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  • 10
    ISSN: 1432-0878
    Keywords: Brain, vertebrate ; Development, ontogenetic ; Proteins, plasma ; Cerebrospinal fluid ; Fetuin ; α2HS glycoprotein ; Human ; Sheep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The human plasma protein, α2HS glycoprotein, has an amino acid composition very similar to that of fetuin, the major protein in fetal calf and lamb serum. Immunohistochemical studies of human fetuses (6–33 weeks gestation) showed that α2HS glycoprotein and fetuin have similar distributions in developing brain and several other tissues, e.g., bone, kidney, gonads, gastrointestinal tract, respiratory and cardiovascular systems. There were notable differences in the liver and thymus in the distribution of the two proteins. Fetuin and α2HS glycoprotein are present in plasma and cerebrospinal fluid of both human and sheep fetuses; their concentrations are reciprocally related: in human plasma and cerebrospinal fluid α2HS glycoprotein concentration is high and fetuin low; the reverse is the case in sheep fetuses. Estimates of the concentration of α2HS glycoprotein in human fetal cerebrospinal fluid and plasma were obtained. It is suggested that α2HS glycoprotein may play a role in developing tissues, especially in the human fetus, similar to that of fetuin in other species.
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