Their infertility resulted, instead, from a failure of oocyte pickup: Yuan et al. Knockout females were infertile, even though they produced normal amounts of oocytes and reproductive hormones. They did this by simultaneously knocking out two clusters of microRNAs (miRs) that, together, are necessary to generate cilia on the epithelial cells of the oviduct tissue/time-targeted knockout narrowed down the effects of the miRs to the adult oviduct epithelium. ( 2) created a strain of female mice whose oviducts were largely devoid of cilia. ( 2) demonstrate that the carpet of tiny motile cilia that coats the lining of the infundibulum is crucial to successful oocyte pickup and transport into the oviduct. Failure of COC pickup can lead to failure of sperm to fertilize the oocyte or, worse, to ectopic implantation of an embryo outside of the uterus. At ovulation, the oocyte plus its cumulus cells and their matrix-the cumulus–oocyte complex (COC)-is released from the ovary and must be pulled into the oviduct, vaulting over a gap between the surface of the ovary and the open end of the oviduct, the infundibulum. As the time of ovulation nears, the granulosa cells close to the oocyte transform into cumulus cells, which begin secreting a hydrated elastic extracellular matrix ( 1). In the ovary, each oocyte matures within a follicle, in which it is surrounded by supportive granulosa cells. A critical step in fertilization of eutherian mammals is the “pickup” of oocytes (eggs) by the oviduct (fallopian tube) from the surface of the ovary.
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