The interstitial gland of ovary of ewes from birth to sexual maturity

The morphological and functional development of the interstitial gland was studied in crossbred ewe lambs (East Friesian × Black-Head Pleven breeds) first birth and then at 1, 2, 3, 4, 5, 5.5 and 6 months, as well as at 1 year in anestrous ewes. Histological and histochemical (AP, NAD · H2-tetrasole reductase, G-6-PDH and Δ5-3β-hydroxysteroid dehydrogenase (Δ5-3β-HSD)) methods and transmission electron microscopy (TEM) were applied while the FSH and LH levels were measured. There was an abundance of epithelial cell cords in newborn animals, while interstitial cells were scanty. Cortical and medullary epithelial cell cords occupied an essential place in the histogenesis of ovine ovarian structures. They were clearly expressed during the whole postnatal period of the development, and showed a species specificity. The development of the interstitial gland was correlated with changes in the gonadotropic hormones. A new population of interstitial glands appeared around puberty in a similar manner to the so-called ‘puberty gland’ in the testis and ovary of humans and other mammals. The results suggest that in these crossbred lambs, puberty was attained between the 3rd and 4th month, and sexual maturity at 5 to 6 months of age.