MANFRED KAGE / SCIENCE PHOTO LIBRARY MANFRED KAGE / SCIENCE PHOTO LIBRARY
Light micrograph of the human ovarian cortex showing developing primary follicles. Formed between the 4th & 7th months of fetal growth, the primordial follicles undergo no further development until sexual maturity. In each ovarian cycle up to 20 primordial follicles are activated to form a primary follice; only one will reach full maturity & be released at ovulation. In the most mature follicle (left), follicular cells (red stain) have proliferated to form a thickened layer, the zona granulosa. A glycoprotein layer (purple), the zona pellucida, encloses the oocyte, the egg cell. Magnification: x125 at 6x7cm size.
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