Mammalian follicles are constituted of a complex structure composed of several layers of
granulosa cells surrounding the oocyte and of theca cells that reside beneath its basement
membrane. During folliculogenesis, granulosa cells separate into two anatomically and
functionally distinct sub-types; the mural cells lining the follicle wall and the oocyte-
surrounding cumulus cells, ie those in intimate metabolic contact with the oocyte. The
cumulus cells connecting with the oocyte have trans-zonal cytoplasmic projections which …