In this new study, the authors used the characteristic architecture of the rhesus macaque ovary, which is similar to the human ovary in terms of morphology and physiology, to devise robust isolation and culture methods for primate primordial follicles. Primordial follicles are con- fined to the ovarian cortex, which is a rigid physical environment com- pared with the medulla where growing follicles are found. They therefore developed a novel double filtration method to isolate large numbers of primordial follicles with minimal manipulation specifically from thin layers of cortical ovarian tissue.