Ultrasonographic imaging of the reproductive tract and surgical recovery of oocytes in Cebus apella (capuchin monkeys)

Two-dimensional real-time and Doppler ultrasonography are valuable non-invasive methods to assess reproductive anatomy and physiology. In adult, postpubertal female Cebus apella (capuchin monkeys), the objectives were to determine (1) uterine and ovarian dimensions, ovarian follicular dynamics, day of ovulation, and arterial blood flow of uterus and utero-ovarian ligament during the follicular phase of the menstrual cycle and (2) the number of oocytes aspirated from antral follicles at laparotomy. Based on two-dimensional, transabdominal B-mode ultrasonography, mean (± S.E.M.) length, height, width, and volume of the uterus were 17.9 ± 0.4, 12.4 ± 0.3, 13.6 ± 0.3 mm, and 1.55 ± 0.08 mL, respectively, and of the ovary were 13.4 ± 0.2, 8.2 ± 0.1, 7.7 ± 0.1 mm, and 4.5 ± 0.2 mL. Ovarian follicles were monitored for 6 days before ovulation, which occurred on day 9.3 ± 0.5 (range, days 7–11; day 1 = start of menses), with 10 of 12 ovulations in the right ovary. Diameter and volume of the preovulatory follicle were 10.1 ± 0.2 mm and 0.55 ± 0.03 mL (on the estimated day of ovulation) and of the CL were 8.1 ± 0.4 mm and 0.3 ± 0.05 mL. Resistivity and pulsatility indices were 0.86 ± 0.02 and 2.15 ± 0.11 for uterine arteries, and were 0.69 ± 0.04 and 1.63 ± 0.15 for the utero-ovarian ligament (UOL) artery; just prior to ovulation, both indices peaked (P < 0.05) in the uterine artery ipsilateral to the side of ovulation, but both reached a nadir (P < 0.05) in the UOL artery. In the absence of ovarian stimulation, 31 oocytes (diameter, 137 ± 10 μm) were aspirated (average of 2 oocytes/(female attempt)) on days 5, 7, and 9. In conclusion, transabdominal ultrasonography facilitated assessment of reproductive anatomy and physiology in C. apella adult females. Resistance and pulsatility indices of uterine and UOL arteries changed near the time of ovulation. Dominant follicles were easiest to aspirate at 8–9 mm in diameter (∼day 9), with intact cumulus-oocyte complexes recovered from ovarian follicles 2–9 mm in diameter.