Browsing by Subject "Prolactin cells"

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    An immunocytochemical study of effects of light deprivation on prolactin cells in the adenohypophysis of the golden hamster
    (Murcia : F. Hernández, 1991) Seu-Mei Wang; Chuen-Lan Liu
    Population ratio and morphology of prolactin cells were studied by employing immunohistochemical methods in the adenohypophysis of normal and experimental golden hamsters of both sexes at 16 weeks of age. Prolactin cells occupied 29% of the total adenohypophyseal cells in the intact males exposed to 141 10 h lightldark schedule. After stimulation of the pineal activity by blinding or exposure of males to continuous darkness for eight weeks, prolactin cells became atrophic and were reduced in population to 17% and 13%, respectively. ~i n e a l e c t om~~r e v e ntot e sdo me extent the effects of the above treatments; thus, prolactin cells constituted 27% in the pinealectomized and blinded hamsters, and 19% in the pinealectomized and darknesstreated group; and their morphology was comparable with that of the intact controls. Prolactin cells in the normal females were apparently larger in size and more numerous as compared with those of the normal males, comprising 47% of cell population in the anterior pituitary. In response to light deprivation, prolactin cells were atrophic with a diminished cytoplasm and decreased in cell number as reflected in the population ratio of 27% in the blinded and 21% in the darknesstreated groups. In pinealectomized females combined with blinding or darkness-treatment, prolactin cells contained an abundance of secretory granules in the cytoplasm and maintained the population ratio comparable to that in the intact females. The present study revealed that light deprivation exerts an inhibitory effect on the secretory activity of prolactin cells and also causes hypoplasia of prolactin cells in the hamster adenohypophysis, the effects being mediated by the pineal gland.
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    Effects of light deprivation on prolactin cells in golden hamsters: an immunoelectron microscopic study
    (Murcia : F. Hernández, 1992) Seu-Mei Wang; Jiahn-Chun Wu; Chia-Man Lue; An-I Tsai; Wen-Ping Chen; Huai-San Lin
    In the golden hamster light deprivation has been shown to induce gonadal regression and reduction of pituitary and plasma levels of prolactin (PRL). In the present study we examined changes in morphology and population ratios of three types of PRL cells 8 weeks after light deprivation, by means of blinding or exposure of hamsters to continuous darkness. In the pituitary of intact hamsters of either sex, which were entrained to a 14-h light: 10-h dark cycle, Type C cells with large secrtetory granules were the most numerous and Type A with smalier granules the least. After light deprivation the pituitary was found to contain remarkably atrophic PRL cells and showed a profound change in population ratio of PRL cell types, Le., Type A cells prevailed over the other two types. Pituitary glands from light-deprived and concurrently pinealectomized hamsters exhibited structures and a population ratio of three types of PRL cells similar to those from intact animals. It is suggested that small-granule-containing PRL cells represent an inactive stage of PRL cells, whereas medium- and large-granule-containing cells are functionally active cells. The atrophy of PRL cells can account for the decreased pituitary leve1 of PRL in light-deprived hamsters reported previously.
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    Immunocytochemical studies on prolactin cells in the adenohypophysis of the golden hamster
    (Murcia : F. Hernández, 1987) Seu-Mei Wang; Chia-Man Lue; Huai-San Lin
    Mammotrophs or prolactin (PRL) cells were identifed in the adenohypophysis of adult golden hamsters by immunocytochemical techniques with a polyclonal anti-PRL, that was proved to be specific to PRL by the dot immunoblotting test. Postembedding immunostaining was performed on Araldite thin sections by immunoperoxidase and immunogold methods. PRL cells were classified into three types according to the different size of the secretory granules. The Type A cells were usually small and angular or oval in shape, and had secretory granules ranging in diameter from 100-230 nm, and showed poorly developed organelles. The Type B and C cells were larger and round or ovoid in shape, contained larger granules, 230-280 nm and 280-570 nm, respectively, and displayed well developed organelles. Immunoreactive PRL cells in the male pituitaries were far less numerous than in the nonpregnant female glands, and were mostly of the Type A and B, whereas in the female the Type C and B cells predominated. In pregnant females, Type C cells became activated and increased in number, while the other two types decreased in proportion. In lactating females, Type A and B cells significantly increased in number at the expense of the Type C cells; meanwhile, the exocytosis of secretory granules was frequently found in all types of PRL cells. The present findings suggest that Type C and B PRL cells, especially the former, are potent in producing and releasing PRL and highly responsive to various physiological stimuli, while Type A cells are probably relatively inert in synthetic activity.