[Morphological changes in the pineal body of domestic swine (Sus scrofa domesticus) depending on light]

The cerebral epiphysis of twelve gilts, aged 6.5 months, was histologically, histochemically, and histometrically tested, after the animals had been kept permanently under artificial light, 100 lux, or in darkness, interrupted twice a day by two hours of lighting, over ten weeks altogether. The parenchymal cells of the epiphyses of the animals kept in darkness changed clearly from those of the other group with constant exposure to light. Changes in the darkness animals included significant enlargement of the cell nuclear volume by 33 per cent, increase in nucleoli count as well as increases of lipids and ribonucleic acid in cytoplasm.