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  • In situ hybridization  (3)
  • Pars intermedia  (2)
  • 1
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Pars intermedia ; Corticotrophic cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Nos observations démontrent l'existence de deux types de cellules glandulaires dans la pars intermedia de l'hypophyse du rat: des cellules propres, à M.S.H., dont les grains de sécrétion sont détruits par la fixation osmiée et relativement bien conservés par la fixation au glutaraldéhyde; des cellules à petits grains denses, osmio-résistants, qui s'apparentent morphologiquement aux éléments corticotropes de l'antéhypophyse. L'existence bien connue d'A.C.T.H. ou, plus précisément, d'un facteur ≪A.C.T.H.-like≫ dans le lobe neuro-intermédiaire nous fait considérer comme très vraisemblable la nature corticotrope de ce deuxième type cellulaire de la pars intermedia.
    Notes: Summary Two types of glandular cells have been shown to occur in the intermediate lobe of the rat hypophysis: 1) M.S.H. producing cells whose secretory granules are destroyed by osmium fixation and relatively well preserved by glutaraldehyde fixation, 2) cells with small dense osmium resistant granules being morphologically similar to the corticotrophic cells of the anterior lobe. The well known occurrence of A.C.T.H. or, more precisely, of an “A.C.T.H.-like” factor in the neuro-intermediate lobe makes the corticotrophic nature of this second cell type very likely.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Fetal intermediate lobe ; Tissue culture ; Immunocytochemistry ; In situ hybridization ; Dopamine ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Organotypic cultures, in defined medium, of pituitary primordia obtained from 15-day-old rat fetuses were performed in order to study the in vitro differentiation of melanotrophic cells. The morphological and ultrastructural features of the transplants resembled those of the gland developing in vivo. In situ hybridization on semi-thin sections, using a 35S-labelled oligonucleotide probe, revealed pro-opiomelanocortin-mRNA-containing cells on the first day of culture in the anterior lobe and after 2–3 days in the intermediate lobe. Immunoperoxidase labelling of adjacent sections showed that the same cells reacted with antibodies against α-melanocyte-stimulating hormone (αMSH), γ3 and adrenocorticotropic hormone in both lobes. The pro-opiomelanocortin-mRNA-containing cells formed progressively conspicuous areas in the intermediate lobe, which was almost uniformly labelled after 6 days. In the anterior lobe, these cells remained scattered in small cell groups, and colloidal gold immunolabelling showed the progressive disappearance of αMSH labelling from the secretory vesicles in cells exhibiting morphological features of adult corticotrophic cells. Both the αMSH content of the explants and αMSH release into the culture medium increased with time. Treatment with the dopamine agonist bromocriptine induced a strong dose-dependent decrease in αMSH secretion, which was significant after 3 days in culture, indicating that dopamine D2 receptors are able to regulate hormonal release of melanotrophic cells at early stages. This system constitutes a suitable model for further studies of factors controlling cell differentiation and cellular interactions involved in histogenesis.
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  • 3
    ISSN: 1432-0878
    Keywords: Key words: Pituitary ; Pars tuberalis ; α-Subunit ; Immunocytochemistry ; In situ hybridization ; Rat ; Mouse ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The nature of the hormone(s) secreted by the pars tuberalis (PT) is still unknown. This pituitary lobe is mainly formed by specific glandular cells that differ in their ultrastructural features from the other adenohypophysial cell types. Data from the literature indicate the presence of thyroid-stimulating hormone immunoreactivity in the PT-specific cells of the rat and the Djungarian hamster but not of other species, including the mouse and guinea-pig. The PT also encloses variable numbers of pars distalis cells, essentially gonadotrophs that are mainly dispersed in its caudal area. We studied the expression of the glycoprotein hormone α-subunit in the PT of the rat, mouse and guinea-pig by in situ hybridization and immunocytochemistry. In situ hybridization, using an oligonucleotide probe complementary to rat cDNA sequence 196–237 revealed the expression of the α-subunit gene throughout the PT of the rat and the mouse; in the guinea-pig, the probe labelled no pituitary cells. Light- and electron-microscopic immunocytochemistry demonstrated α-subunit immunoreactivity in the secretory granules of the PT-specific cells in the three species examined. These cells did not react with a specific antibody against the β-subunit of luteinizing hormone, an antibody that labelled scattered gonadotrophs. The present data suggest that hormone(s) produced by the PT-specific glandular cells are, at least partly, related to glycoprotein hormones.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Keywords: Pituitary ; Pars tuberalis ; α-Subunit ; Immunocytochemistry ; In situ hybridization ; Rat ; Mouse ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The nature of the hormone(s) secreted by the pars tuberalis (PT) is still unknown. This pituitary lobe is mainly formed by specific glandular cells that differ in their ultrastructural features from the other adenohypophysial cell types. Data from the literature indicate the presence of thyroid-stimulating hormone immunoreactivity in the PT-specific cells of the rat and the Djungarian hamster but not of other species, including the mouse and guinea-pig. The PT also encloses variable numbers of pars distalis cells, essentially gonadotrophs that are mainly dispersed in its caudal area. We studied the expression of the glycoprotein hormone α-subunit in the PT of the rat, mouse and guinea-pig by in situ hybridization and immunocytochemistry. In situ hybridization, using an oligonucleotide probe complementary to rat cDNA sequence 196–237 revealed the expression of the α-subunit gene throughout the PT of the rat and the mouse; in the guinea-pig, the probe labelled no pituitary cells. Light-and electron-microscopic immunocytochemistry demonstrated α-subunit immunoreactivity in the secretory granules of the PT-specific cells in the three species examined. These cells did not react with a specific antibody against the β-subunit of luteinizing hormone, an antibody that labelled scattered gonadotrops. The present data suggest that hormone(s) produced by the PT-specific glandular cells are, at least partly, related to glycoprotein hormones.
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  • 5
    ISSN: 1432-0878
    Keywords: Pars intermedia ; Oxytocin ; Dopamine ; Serotonin ; Immunocytochemistry ; Rabbit, hare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pars intermedia of the pituitary in the rabbit and hare is abundantly innervated by axons reacting selectively with antibodies against oxytocin. These axons contain dense secretory vesicles about 140 nm in diameter, i.e., smaller than those in the neurosecretory axons of the neural lobe. No fiber elements staining for other peptides (vasopressin, somatostatin, substance P) were observed in the pars intermedia, except rare leu-enkephalin axons restricted to the rostral zone of the gland. Dopaminergic innervation appears to be completely absent from the intermediate lobe. This was shown by the lack of reaction with an antibody against tyrosine-hydroxylase, which did reveal a well-developed tubero-infundibular system of nerve fibers. Axons reacting with an antibody against serotonin were irregularly distributed in the pars intermedia. In the absence of dopaminergic axons, the extensive oxytocin-like innervation may play a major role in regulating the melanotrophic cell activity in the Leporidae.
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