Functional Significance of the Cells in the Pars Anterior of the Pituitary Gland of the Musk Shrew (Suncus Murinus L.)

Abstract

Seven morphologically and tinctorially distinct types of cells (types 1--7) have been distinguished in the pars anterior of the pituitary gland of the musk shrew (Suncus murinus L.). On the basis of their responses to various experimental stimuli, these cell types were correlated with the secretion of various trophic hormones. Type 1 cells exhibited conspicuous changes after thyroidectomy or inactivation of the thyroid gland and hence appeared to be the source of TSH. Types 2 and 3 cells responded to gonadectomy and administration of androgens, which suggests that they were associated with gonadotrophin secretion. The granules of the type 2, but not the type 3 cells could be extracted with 10% trichloroacetic acid, which may indicate that type 2 and 3 cells secrete FSH and LH respectively. After the administration of either reserpine or oestrogen, the type 4 cells underwent hypertrophy and hyperplasia, which suggests that they were the likely source of prolactin. Type 6 cells, which are distinguishable from type 4 cells by their thinly dispersed erythrosinophilic granulation, showed conspicuous changes after unilateral adrenalectomy, administration of metyrapone or exposure to stress and may therefore be responsible for secretion of ACTH. Type 5 cells tinctorially resembled the somatotrophic cells of other mammalian species and did not respond to any of the experimental treatments used in the present study. It is therefore possible that these cells have a somatotrophic function. The possible significance of type 7 cells has been discussed previously.

Testosterone Propionate Induced Changes in Testicular Phosphatases of Musk Shrew (Suncus murinus L.)/Testosteronpropionatinduzierte Veränderungen der Hoden-Phosphatasen von Bisammaus (Suncus murinus L.)

“…We are aware of the fact that any effect of TP on testis cannot be delineated from the effects produced on testis by changes in levels of circulatory gonadotrophins as a result of feedback mechanism. However, failure to observe any decrease in testis weight in the present investigation and failure to observe any noticeable change in cytology of gonadotrophs of pituitary gland of shrew in response to high dose of TP for much longer duration (Naik and Dominic -1978) suggested that the effects produced on testis by TP may be direct one rather than through changes in the levels of circulatory gonadotrophins. In this context it should be further mentioned that feedback mechanism of pituitary-testicular axis in shrew is reported to be somewhat different from other scrota1 mammals (Furumura et al -1985).…”

Three-dimensional distribution patterns of PRL, GH and ACTH cells in the house musk shrew (Suncus murinus)

“…Naik and Dominic (1972) distinguished seven tinctorially distinct cell types in wild shrews and drew schematic distribution maps. Later, they determined the functions of six cell types on the basis of the cellular responses to various experimental stimuli: thyroidectomy, gonadectomy, adrenalectomy, and administration of androgen, gonadotrophin, prolactin, L-thyroxine, or estrogen (Naik and Dominic 1978). Their 2D observations gave a great insight into the distribution patterns of pituitary cells in the wild shrew, but the authors did not classify cells immunohistochemically or demonstrate their distribution patterns spatially in the whole anterior pituitary.…”