Cytological and Cytochemical Investigations of the Adenohypophysis of the Sheep

Six types of cells were identified in the pars distalis of the sheep adenohypophysis using various tinctorial methods and cytochemical reactions: They were two types of acidophils (alpha and epsilon), two types of amphophils (zeta and delta 1) and two types of basophils (beta and delta 2). Various experiments such as castration, thyroidectomy and adrenalectomy were carried out to examine the changes in each cell type.The alpha cells were stained orange with orange G in trichrome or tetrachrome methods and showed acid hematein positive but PAS negative reaction. They were located throughout the gland except the zona tuberalis.The epsilon cells were stained red with acid fuchsin, azocarmine or erythrosin and showed positive reaction for the acid hematein test and PAS method. They were larger than the alpha cells and were distributed throughout the pars distalis especially in its peripheral area.The zeta cells were amphophilic cells stained purple with aniline blue and acid fuchsin in trichrome method. Their granules were PAS positive, but AF and AT negative, and were R type after the PFA/AB/PAS/OG method. The zeta cells were large, irregular or polygonal cells distributed in the central portion of the pars distalis. They were considered to be the only source of ACTH, since they increased in number and size and showed a marked degranulation after adrenalectomy.The beta cells were large polygonal basophils which were confined to the zona tuberalis. The PAS positive granules of the beta cells were stained selectively by AF and alcian blue but not by AT or methyl blue. The beta cells were considered to be thyrotrophs, because, after thyroidectomy, they became enlarged and degranulated cells identical with thyroidectomy cells.The delta 1 cells were small, round or oval amphophilic cells stained reddish purple with both aniline blue and acid fuchsin in the trichrome method. They were distributed throughout the pars distalis. Their granules were coarse and stained blue-black or purple in AT, purple in PAS and methyl blue, but not stained by AF.The delta 2 cells were large, oval or rounded basophilic cells and were stained light blue with aniline blue in the trichrome method. The granules of delta 2 cells showed a weak positive reaction for PAS and AT but not for AF. After castration, the delta 1 and delta 2 cells increased in number and size, degranulated, and developed into castration cells, which contained larger or smaller vacuoles in their cytoplasm. These cells were considered to be gonadotrophs.