3 research outputs found
Immunocytochemical studies on prolactin cells in the adenohypophysis of the golden hamster
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
Differential Expression of Alternatively Spliced Forms of MAP4: A Repertoire of Structurally Different Microtubule-Binding Domains
Effects of light deprivation on prolactin cells in golden hamsters: an immunoelectron microscopic study
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