| Research Abstract |
(1) By administration of dopamine into the common carotid artery of host animals transplanted pituitary tissues under the kidney capsule the secreting granules in prolactin (PRL) secreting cells became rather smaller and barrier-like structure enclosed the granules, showing inhibition of hormone-release.
(2) Rod-shaped secretory granules were observed in pituitary growth hormone (GH) secreting cells, but not in PRL-cells, of pregnant and lactating musk shrew. To our knowledge, this is the first report concerned with rod-shaped secretory granules observed in the anterior pituitary cells.
(3) Numerous intracisternal granules were observed in the rough endoplasmic reticulum of pituitary PRL-cells in pregnant, lactating and estrogen-treated musk shrew. This phenomenon may indicate one of disposing way of over-produced PRL. No reports, to our knowledge, has been published in regards to these intracisternal granules in PRL-cells.
(4) The secretory granules in pituitary GH-cells, as well as PRL-
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cells, of diabetic rats were all smaller than normal ones, but the administration of insulin recovered these atrophic changes to near normal state. This indicates that there is a close relationship between morphological features secretory granules and cellular function.
(5) Localization of GH and PRL in separate secretory granules of same cells and coexistence of both hormones in a same granules were observed in the anterior pituitary glands of pregnant rat and musk shrew as well as in lactating musk shrew. Consequently, we recognized the existence of "somatomammotroph".
(6) No pure PRL-containing secretory granules were observed in the anterior pituitary glands of normal and hibernating Japanese house bats, and PRL were observed in only somatomammotroph. However, during pregnant and lactating periods the size of PRL-cells and also PRL-contaning granules and the ratio of PRL- granules in the single cell were obviously increased.
(7) Partial hepatectomy enhanced morphlolgically cellular function of PRL-cells in the rat, and the granule-extrusion in PRL-cells were increased. Less
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