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An experiment was conducted to examine the appearance of the seminiferous tubule 20 days after a single exposure of the testes of rams to a scrotal temperature of about 42 degrees C for 45 min. Ten of the animals were surgically hypophysectomized and five were simultaneously heated; these rams were treated twice a day with ovine pituitary extract to avoid modifications in the negative feedback from the testes to the pituitary and consequent changes in gonadotrophin secretion. Six intact rams (three heated and three unheated) were also studied. The pituitary extract significantly increased the testis weight and spermatogonial multiplications from A1 spermatogonia onwards. Twenty days after the heat treatment, testis weight was significantly reduced by heating; both tubular and intertubular tissues were affected. The total length of seminiferous tubules per testis was not modified, whereas the mean seminiferous tubule diameter was significantly reduced after heating. The total number of Sertoli cells per testis was not significantly modified, while their mean cross-sectional nuclear area was significantly reduced by heat treatment. A decrease in the number of all germ cells except A0 spermatogonia, from A1 spermatogonia onwards, was observed. The number of round spermatids decreased by 95 and 90%, slightly more than the diplotene primary spermatocytes (76 and 77%) and elongated spermatids (79 and 85%) in hypophysectomized pituitary extract-treated and intact rams, respectively. Round and elongated spermatids would be derived from germ cells that were respectively leptotene and young pachytene primary spermatocytes at the time of heating, whereas diplotene primary spermatocytes would have been type B spermatogonia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of a single brief period of moderate heating of the testes on seminiferous tubules in hypophysectomized rams treated with pituitary extract