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The spermatogenic process of normal rats at 20, 32, and 44 days of age was characterized. Variations in numbers of degenerating and abnormal cells were noted during the cycle in most age groups, indicating a stage-related vulnerability of these cells. The most advanced cell types that were seen at a particular age were frequently abnormal or degenerating. When the numbers of viable cells available to degenerate were considered, the degeneration rate in normal pubertal animals was about 15, 10, and 2 times greater in 20-, 32-, and 44-day-old animals, respectively, than in 75-day-old animals. In 32-day-old rats, neither hypophysectomy nor hypophysectomy and subsequent hormone supplementation resulted in an alteration in the qualitative pattern of germ cell degeneration during the spermatogenic cycle compared with that in the normal animal; however, the treatments did alter the quantitative response of cellular degeneration. Three days posthypophysectomy there was a marked increase in the numbers of total degenerating germ cells. FSH (60 micrograms) given twice daily (as were all hormones) reduced the numbers of degenerating cells significantly, as did LH (13 micrograms). Low dose LH (0.3 micrograms), representing the approximate contaminating dose of LH in the 60-micrograms FSH preparation, and low dose FSH (30 micrograms) did not elicit a response significantly different from that to hypophysectomy alone. LH (13 micrograms) plus FSH (60 micrograms) reduced the levels of degenerating cells such that there was no significant difference from levels in intact 32-day-old rats. The data indicated, for the cell types studied, a lack of specificity of various hormones or hormone combinations in the survival of specific germ cell types. It emphasizes the importance of FSH in pubertal spermatogenesis as well as the synergistic actions of LH and FSH.

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No abstract

The purpose of this experiment was to determine whether surgical stress on the morning of proestrus would elicit an early release of gonadotropin from the pituitary. Animals exhibiting 5-day estrous cycles underwent bilateral sham-ovariectomy under ether anesthesia at 0800 h of proestrus. These animals had high levels of progesterone and estradiol following the surgery. These steroids were thought to be adrenal in origin, since animals adrenalectomized at 0800 h of proestrus had low progesterone levels and estradiol comparable to unoperated controls. Subsequently, the sham-operated animals showed high FSH but not LH values at 1300 h, prior to the normal critical period for gonadotropin release. By 1400, the LH surge had begun, and progesterone was again being released. Adrenalectomized and unoperated controls showed no increase in any steroid or gonadotropin measured before 1400 h. These findings suggest that stress-induced release of adrenal estradiol and progesterone, rather than some other consequence of the surgical procedure, during the morning of proestrus, can advance the onset of release of FSH, prior to LH. Ovariectomy at 0800 h proestrus led to a rapid and dramatic increase in FSH but not LH secretion by 4 h after surgery. By 6 h after ovariectomy FSH had increased to six times control values and LH had increased to twice control values. Estradiol remained at control values for 6 h following surgery but 20alpha-hydroxypreg-4-en-3-one (20alpha-OHP) dropped quickly to baseline values. It is possible that a reduction in circulating 20 alpha-OHP may be responsible for the increases in FSH prior to LH in this group, but the absence of other negative feedback factors from the ovary or adrenal may also be involved.