Egg cell. Coloured Scanning Electron Micrograph (SEM) of a developing egg cell in a secondary follicle of the ovary. At centre is the rounded egg cell or secondary oocyte (pink). It is surrounded by granulosa cells (blue) which serve to nourish the egg during its developmental stages. Between granulosa cells (at right, yellow) a space develops called the follicular antrum, into which follicular fluid is secreted. This egg is still immature. The secondary follicle must develop into a graafian follicle before the egg is fully mature and ready to be released for fertili- sation. Magnification: x720 at 6x7cm size. Magnification: x915 at 4x5 inch size.