Secondary follicles in ovary Coloured Scanning Electron Micrograph SEM of ovary tissue showing two secondary follicles A developing egg or secondary oocyte pink is seen at the centre of one follicle Follicles are surrounded by theca green tissue which secretes steroids Inside the theca are granulosa cells blue which nourish the developing egg Between granulosa cells a space develops at centre right brown called the follicular antrum into which follicular fluid is secreted Secondary follicles must develop into graafian follicles before the egg is fully mature Magnification x at xcm size Magnification x at x inch size