Graafian follicle(redirected from Graaf, Reijnier de)
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(named after R. de Graaf), a mul-tilayered saclike follicle that develops in the cortical layer of the ovary of mammals, including humans, under the influence of the follicle-stimulating hormone. The wall of the Graafian follicle consists of an external layer of connective tissue, under which is the multilayered follicular epithelium lining the Graafian follicle cavity, which is filled with a serous liquid. The epithelium forms a process into the Graafian follicle cavity (cumulus oophorus), in which the ovum is located, and provides it with nutrients. The developing follicle produces the hormone estrogen, which prepares the sexual ducts to receive the egg after ovulation, that is, its release from the Graafian follicle and the ovary. The ovulated egg enters the oviduct, where it can join with a spermatozoon and be fertilized. In animals that bear many young at once, several Graafian follicles grow and mature simultaneously.
D. A. POTEMKINA