Retrieval of rhesus monkey (Macaca mulatta) oocytes by ultrasound-guided needle aspiration: problems and solutions

Oocytes of nonhuman primates such as rhesus monkeys are excellent models for diverse studies on developmental biology, epigenetics, human reproduction, and assisted reproductive technologies, as well as on transgenics. Such studies require numerous oocytes that can be retrieved after controlled ovarian stimulation. Currently, most primate centers use laparoscopic aspiration or laparotomy followed by aspiration to collect rhesus oocytes, although the ultrasound-guided needle aspiration is more advantageous due to reduced infection risk, less injury, and a shorter recovery period. Yet, some initial difficulties associated with the ultrasound-guided needle aspiration limit its broader application. The objective of the present study was to address these obstacles. By presenting practical solutions to the initial difficulties, results from our study show that it is possible to collect a mean number of 38 +/- 10 rhesus oocytes per hormonally stimulated female. These results compare favorably to the average number of rhesus oocytes collected using the laparoscopic approach and suggest that when initial obstacles are overcome, the ultrasound-guided oocyte retrieval represents a good alternative to more invasive approaches.