The effects of photoperiod and melatonin injections on the reproductive system of pinealectomized male mice Mus musculus, ICR strain

One hundred two male mice , Mus musculus, ICR strain, age four weeks, were obtained. Fifty-one mice were pinealectomized and 51 were sham operated. The animals were divided into three photoperiod groups: 1.5L:22.5D, 14L:10D, 24L; 0D. The mice were subcutaneously injected daily with 10 ug melatonin or control solution from post-operative day J to post-operative day 60, On post-operative day 60 representatives of each photo­ period-surgery-injection regimen were paired with females. The remaining animals were killed and several organs were removed and weighed, Melatonin injections were progonadal in pinealectomized mice and inhibitory in sham mice in several instances. Histological examination of testis sections indicated normal spermatogenesis and the presence of mature sperm, A reproductive study indicated that all mice were capable of siring offspring irrespective of treatment. Doubt is cast on the significance of the pineal to the reproductive competence of male laboratory mice