A comparison of blinding and afternoon melatonin injections on the histology of the reproductive organs, pineal ultrastructure and gonadotrophin hormone levels in female Syrian hamsters

Late afternoon injections of 25 μg melatonin mimics the effects of blinding on reproductive organ weights and histology in adult female hamsters. Uteri from indole-treated and blinded animals were infantile in appearance; the ovaries of these groups were smooth, brown and devoid of corpora lutea. A prominent feature of the ultrastructure of the pineal from these sexually regressed hamsters was the marked proliferation of smooth agranular endoplasmic reticulum.