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HAROLD G. SPIES, GORDON D. NISWENDER, Blockade of the Surge of Preovulatory Serum Luteinizing Hormone and Ovulation with Exogenous Progesterone in Cycling Rhesus (Macaca mulatta) Monkeys, The Journal of Clinical Endocrinology & Metabolism, Volume 32, Issue 3, 1 March 1971, Pages 309–316, https://doi.org/10.1210/jcem-32-3-309
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Abstract
Blood serum levels of luteinizing hormone (LH) were measured by a double antibody radioimmunoassay in 9 mature rhesus (Macaca mulatto) females between days 9–18 of the menstrual cycle and in subsequent cycles while the monkeys were treated with progesterone. Blood samples were collected at 8 am and 4 pm on each day. Progesterone was injected sc once daily at a level of either 0.5, 2.0 or 5.0 mg/individual. Midcycle elevations of LH suggestive of ovulation were found in 8 of the 9 control cycles. All 3 levels of progesterone blocked the preovulatory rise in serum LH, but the 0.5 mg level was most effective. Base line levels of serum LH were similar among the 3 groups treated with progesterone (p>0.05). Repeated laparotomies were performed on 8 other females and their ovaries were examined for evidence of follicular development, ovulation and formation of a corpus luteum between days 4–23 of control cycles and in subsequent cycles in which they were injected with progesterone. Only small follicles of less than 2 mm diameter were noted until the late follicular phase, when they reached 4–5 mm. During the luteal phase of the cycle, follicles did not exceed 2 mm. Ovulation as evidenced by the presence of a corpus luteum was observed in control cycles. When progesterone was injected, ovulation was blocked in 5 of 7 females. Follicular development was greater in monkeys injected with 0.5 mg than in those receiving 2.0 or 5.0 mg. The data indicate that 0.5 mg of progesterone daily blocks the preovulatory rise in serum LH and ovulation in the rhesus monkey and causes less suppression of follicular development than does 2.0 or 5.0 mg.
