Effects of pinealectomy in the newborn female rat

That pinealectomy in the rat is followed by ovarian hypertrophy is an assumption which is rather widely accepted and which is fundamental to much contemporary pineal research. Nevertheless an analysis of the alleged supporting literature shows it to be surprisingly weak and limited to animals operated at three to four weeks of age. In several mammals young pineals have been shown to equal or exceed older pineals in certain metabolic activities, but the effect of pineal ablation in the newborn rat is unknown. This report is based on Holtzman female rats pinealectomized at three days, and sacrificed at 60 days of age. The animals comprise a littermate series of eight normal, eight sham operated and eight pinealectomized; and a non littermate series of 18 normal, 17 sham operated, and ten pinealectomized rats. Pinealectomy was proved complete by microscopy of serial sections. Pinealectomized animals in both series did not differ from normals in the weight of the body, ovary, uterus, adrenal, or hypophysis; nor was there a difference in time of vaginal opening, estrous cycle, or 24 hour urinary sodium and potassium output.