Date of Award


Document Type


Degree Name

Master of Science




This work was undertaken to study the effects of photoperiod and melatonin on fertility in male Mongolian gerbils (Meriones unguiculatus). Four groups of fifteen animals each, were placed in different photoperiods (ambient, ranging from 14L:10D to 11.3L:12.3D; 24L:10D; 14L:10D; and 1L:23D). After 35 days, three gerbils from each photoperiod condition were sacrificed and the testes, epididymides, seminal vesicles, prostate, kidneys, adrenals, thymus and hypophysis were weighed. The testes and epididymides were placed in Bouin's fixative and used for histological studies. Also, two males from each photoperiod condition were paired individually with a female. The remaining animals of each photoperiod condition were divided into two subgroups that received melatonin or vehicle injections for 35 days. After that, the gerbils were killed and the same organs examined. Photoperiod alone or combined with melatonin injection neither enhanced nor inhibited the body weight, sexual organs and other organs by 70 days. The presence of spermatozoa in both the testes and epididymides, and the offspring obtained of the animals exposed to different photoperiods and melatonin, indicate no dependence of the process of sexual maturation and reproduction in the Mongolian gerbil on these factors.

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