Photographs of 25 μm thick sections through the ovaries of prepubertal African elephant calves (Scale bar = 10 mm). a) At 2 months of age, abundant interstitial tissue is visible within the medulla. Several small antral follicles are seen on the cortico-medullary border, these are now regarded as being in the cortex even though they may bulge into the medulla. Artifacts marked with a # are pin holes. b) At 1 year of age, the cortical depth is greater than in (a) and isolated larger antral follicles may be seen. Interstitial tissue is present in streaks within the medulla. c) At 1.5 years of age, interstitial tissue is visible within the medulla and antral follicles are observed more frequently than in (b). d) By 3 years of age, the ovary is settling into its adult pattern of antral follicles residing wholly within the true cortex. e) At 4.5 years, the ovary is now starting to enlarge due to a considerable increase in the volume of the cortex.