HISTOLOGICAL AND BIOCHEMICAL-CHANGES IN THE OVARY AND UTERUS OF ZINC-DEFICIENT SPRAGUE-DAWLEY RATS

Female Sprague Dawley rats fed on zinc deficient (1 ppm) as well as marginal zinc deficient (ZnD, 6 ppm) diets for 3 and 6 weeks exhibited spiny hair coat, loss of hair and erratic estrous cycle as compared to their respective controls. Histological studies of ovary from all sets of ZnD groups revealed atresia of varying degree. Graafian follicles were characterized by necrosis in zona granulosa cells, poorly developed zona pellucida and corona radiata, and shrinkage in oocyte. Secondary follicles from ZnD rats exhibited necrotic and disorganized zona granulosa, detached corona radiata, vacuolization in oocyte cytoplasm and condensed chromatin. Primary follicles from ZnD rats appeared necrotic with vacuolization in oocyte cytoplasm. Uterus from all sets of ZnD rats displayed glandular structures devoid of secretions, the epithelial cell linings of lamina propria had several necrotic cells and the cell height and nuclear diameters of the epithelial cells of lamina propria had decreased. Zinc, protein and cholesterol decreased in ovaries, uteri and serum of all the animals from ZnD rats while the other biochemical parameters followed no uniform pattern. Conclusively, zinc deficiency could have resulted into loss of appetite thereby reducing the energy and protein intake, reduction in secretions of GnRH by the hypothalamus and LH and FSH by hypophysis, increased synthesis and/or secretions of prolactin, reduced output of estrogen, and eventually to arrest of ovulation, increased atresia of follicles and atrophy of uterus.