Goat pituitary glands were immunohistochemically studied with antisera for bovine S-100 protein, rat LH beta, FSH, TSH beta, prolactin, ovine GH, and porcine ACTH1-39 by use of the superimposition technique on adjacent sections. Folliculo-stellate (F-S) cells were divided into two categories on the basis of ultrastructural properties: One consisted of a mass of agranular cells in which the pseudolumina were equipped with microvilli and cilia. Elongate gap junctions were often observed among these cells. The other was a group of granulated cells with or without pseudolumina. In this group the gap junctions were shown to be disintegrated. The dense granules 150-250 nm in diameter began to accumulate in the cells. However, neither type of these F-S cells was immunostained for S-100 protein. On the other hand, numerous polygonal, elongate, irregular or stellate cells containing S-100 protein were distributed throughout the gland. Most of them were immunohistochemically identical with the GH cells laden with the secretory granules 250-450 nm in diameter, but some of them were identical to TSH and prolactin cells which immunostained faintly for S-100 protein. This appears to be the first demonstration of GH cells intensely immunostained for S-100 protein.

Anti-laminin-positive gonadotrophs in the anterior pituitary were immunocytochemically examined in rats of either sex at various ages. In the male, the ratio of the cell number of the positive cells to that of gonadotrophs gradually increased until day 60 when a plateau (70-80%) was reached. In the female, on the contrary, the ratio reached the maximal level (--60%) at day 30, but then suddenly decreased within l0 days (-5%). The results suggest that the level of laminin-like protein relates to the cyclic gonadotropin secretion accompanied by the estrous cycle in the female. i

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