Hormonal Regulation of Ovarian Folliculogenesis in Rhesus Monkeys. II. Serum Concentrations of Estradiol-17β and Follicle Stimulating Hormone Associated with Growth and Identification of the Preovulatory Follicle

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Abstract
This study was designed to provide a detailed description of preovulatory follicular development and the associated hormonal patterns in rhesus monkeys. Follicular morphology was observed by laparoscopy, performed sequentially, during 20 menstrual cycles in 13 rhesus monkeys. Serum concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol-17β (E2) and progesterone were determined by radioimmunoassay. We conclude that: a) follicular growth occurs in a curvilinear fashion, increasing from an average of 1.7 mm to 9.4 mm during the 11 days preceding the LH peak; b) the follicle destined for ovulation can be grossly identified as early as 9 days before the preovulatory gonadotropin surge in some animals, but with increasing confidence on Day -5; c) only in the minority of cycles do waves of follicular development occur in the ovaries of rhesus monkeys and then only during the early follicular phase; d) serum concentrations of E2 are linearly related to follicle size (P<0.01); and e) a curvilinear relationship (P<0.002) exists between serum concentrations of FSH and the follicle diameter.