Experimental study on the effects of melatonin administration on the ovary and the oviduct in the adult mice [electronic resource].

Includes references.

The aim of the present work is to demonstrate the effect of the melatonin administration for different periods of time on the ovarian follicles and the oviductal epithelium in the adult mice. Also the reversibility of melatonim effect is studied in a trial for assessment of its effect on the fertility in females. In this work, a high dose (8.0 mg/kg) and a low dose (4.0 mg/kg) of melatonin were used. Melatonin was injected to the animals subcutaneously once daily in the late afternoon. A total number of 40 young adult female mice were used. At the beginning of the experiments, they were two months old. Animals were divided into eight groups. Groups I and II composed of three and four months old control animals. Group III received the low dose of melatonin for one month and group IV received the same dose for two months. Group V received the high dose of melatonin for one month and group VI received the same dose for two months. At the end of the experiments, animals received the treatment for one month became three months old and those received the treatment for two months became four months old. Group VII composed of seven months old control animals. Group VIII composed of recovered animals (animals allowed to survive three months without treatment after receiving the high dose for two months). At the end of the experiment, the recovered animals became seven months old. Animals were sacrificed, their ovaries and the oviducts were removed and processed for histological examination after staining with Haematoxylin and Eosin. Some specimens of the ampulla of the oviduct were processed for ultrastructural study with transmission electron microscope. The numerical density and the diameter of the primary follicles, growing follicles and corpora lutea in the ovaries of all groups of animals were measured and statistically analyzed. The results of the present work demonstrated apparent increase in the size of the ovary in the melatonin treated animals. The numerical density and the diameter of the growing follicles and corpora lutea in all melatonin treated groups showed significant increase in comparison with their corresponding control. The primary follicles showed significant reduction in their numerical density in melatonin treated animals as compared with the control. In the recovered animals, the size and the structure of the ovary appeared nearly similar to the control. Also the numerical density and the diameter of the primary follicles, growing follicles and corpora lutea showed non significant change in comparison with their corresponding control. The oviductal epithelium of the ampulla in the high dose melatonin treated animals showed predominance of the secretory cells. The ultrastructual study of these cells revealed that the apical surface had -many microvilli and their cytoplasm contained a lot of secretory granules. In conclusion, this study revealed that nighttime melatonin administration had a stimulatory effect on the ovarian follicular growth. This effect was independent to the dose or the duration of its administration. The oviductal epithelium showed predominance of secretory cells. Its effect on the ovary was reversible. This may provide in the future new insights and directions for the study of its role in the physiology and pharmacology of fertility and contraception in animals and humans.

Summary in Arabic.