Functions of the cumulus oophorus include coordination of follicular development and oocyte maturation.

This results in an expanding or dispersed pattern of the cumulus oophorus around the egg cell, facilitating its identification within follicular fluid.

In addition, progesterone may inwardly guide spermatozoa, already present within the periphery of the cumulus oophorus (Teves et al., 2006).

Included in the follicles are the cumulus oophorus, membrana granulosa (and the granulosa cells inside it), corona radiata, zona pellucida, and primary oocyte.

In the primary ovarian follicle, and later in follicle development (folliculogenesis), granulosa cells advance to form a multilayered cumulus oophorus surrounding the oocyte in the preovulatory or antral (or Graafian) follicle.

Spermatozoa that are already deep within the cumulus oophorus may sense the more potent chemoattractant that is secreted from the oocyte (Sun et al., 2005) and chemotactically guide themselves to the oocyte according to the gradient of this chemoattractant.

For the structure in neuroanatomy, see Corona radiata The corona radiata is the innermost layer of the cumulus oophorus and is directly adjacent to the zona pellucida, the outer protective layer of the ovum.

Spermatozoa have been shown to respond to the temperature gradient of 2 C between the oviduct and the ampulla, and chemotactic gradients of progesterone have been confirmed as the signal emanating from the cumulus oophorus cells surrounding rabbit and human oocytes.

By the end of the follicular, or proliferative, phase of the thirteenth day of the menstrual cycle, the cumulus oophorus layer of the preovulatory follicle will develop an opening, or stigma, and excrete the oocyte with a complement of cumulus cells in a process called ovulation.