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Either blinding or the injection of 1 milligram of testosterone propionate into male Sprague-Dawley rats, 3 days old, results in testes and accessory organs (seminal vesicles and coagulating glands) that are smaller than normal when the rats are 72 days old. The response to blinding is prevented by removal of the pineal gland, whereas the response to treatment with testosterone is unaffected by pinealectomy. Combination of the two treatments in 3-day- old rats causes testes to be less than one-third their normal size at 72 days of age; pinealectomy in these rats permits the reproductive organs to grow to the same size as those in the androgen-treated animals.

Charcoal-extracted porcine follicular fluid (PFF), when injected at 1200 h on proestrus, blocked the primary FSH surge seen at 1700 and at 1830 h without affecting the LH surge. In contrast, if the injection was withheld until 1330 h, the FSH surge occurred in the normal way at 1700 h but was suppressed at the 1830 h autopsy. The suppression of FSH by 0.5 ml PFF at 1200 h had abated by 0400 h of estrus. The blockade of the primary surge of FSH at 1700 and 1830 h did not prevent ovulation, nor did it prevent the expected rise in serum progesterone or fall of estradiol levels. There appears to be a latency of at least 3.5 h, when PFF is administered ip, before FSH can be suppressed. This latency occurs whether the injection is carried out in intact proestrous rats or in acutely or chronically ovariectomized females.