From primordial germ cells to primordial follicles: a review and visual representation of early ovarian development in mice.

BACKGROUND: Normal development of reproductive organs is crucial for successful reproduction. In mice the early ovarian developmental process occurs during the embryonic and postnatal period and is regulated through a series of molecular signaling events. Early ovarian development in mice is a seventeen-day process that begins with the rise of six primordial germ cells on embryonic day five (E5) and ends with the formation of primordial follicles on postnatal day two (P2). RESULTS: We reviewed the current literature and created a visual representation of early ovarian development that depicts the important molecular events and associated phenotypic outcomes based on primary data. The visual representation shows the timeline of key signaling interactions and regulation of protein expression in different cells involved in ovarian development. The major developmental events were divided into five phases: 1) origin of germ cells and maintenance of pluripotency; 2) primordial germ cell migration; 3) sex differentiation; 4) formation of germ cell nests; and 5) germ cell nest breakdown and primordial follicle formation. CONCLUSIONS: This review and visual representation provide a summary of the current scientific understanding of the key regulation and signaling during ovarian development and highlights areas needing further study. The visual representation can be used as an educational resource to link molecular events with phenotypic outcomes; serves as a tool to generate new hypotheses and predictions of adverse reproductive outcomes due to perturbations at the molecular and cellular levels; and provides a comprehendible foundation for computational model development and hypothesis testing.

Effects of anesthesia with isoflurane, ketamine, or propofol on physiologic parameters in neonatal rhesus macaques (Macaca mulatta).

Isoflurane, ketamine, and propofol are common anesthetics in human and nonhuman primate medicine. However, scant normative data exist regarding the response of neonatal macaques to these anesthetics. We compared the effects of isoflurane, ketamine, and propofol anesthesia on physiologic parameters in neonatal rhesus macaques. Neonatal rhesus macaques (age, 5 to 7 d) were exposed to isoflurane (n = 5), ketamine (n = 4), propofol (n = 4) or no anesthesia (n = 5) for 5 h. The anesthetics were titrated to achieve a moderate anesthetic plane, and heart rate, blood pressure, respiratory rate, end tidal carbon dioxide, oxygen saturation, and temperature were measured every 15 min. Venous blood samples were collected to determine blood gases and metabolic status at baseline, 0.5, 2.5, and 4.5 h after induction and at 3 h after the end of anesthesia. Compared with ketamine, isoflurane caused more hypotensive events and necessitated the administration of increased volumes of intravenous fluids to support blood pressure throughout anesthesia; no significant differences were observed between the isoflurane and propofol groups for these parameters. In addition, isoflurane resulted in a significantly shorter average time to extubation, compared with both ketamine and propofol. Due to supportive care, other physiologic variables remained stable between anesthetic regimens and throughout the 5-h exposure. These data improve our understanding of the effects of these 3 anesthetics in neonatal rhesus macaques and will aid veterinarians and researchers as they consider the risks and benefits of and resources required during general anesthesia in these animals.