Ultrastructural interrelationship between the pineal gland and the testis in the male rat

The ultrastructural interrelationship between the pineal gland and testis w as evaluated in the rat. Wistar rats were divided into 6 groups. Groups I a nd II were sham-orchidectomized and orchidectomized rats, respectively. Rat s in group III were orchidectomized and daily injected with testosterone pr opionate (TP) for 1 month. Groups IV and V were sham-pinealectomized and pi nealectomized, respectively. Group VI was pinealectomized and dairy injecte d with melatonin for 2 months. All animals were anesthetized with ketamine for fixation by vascular perfusion. Pineal glands of groups I, II, and III and the testes of groups IV, V, and VI were removed and weighed. All specim ens were examined by electron microscopy. Orchidectomy caused an increase o f lipid droplets, cytoplasmic dense bodies, and lysosomes. Rough endoplasmi c reticulum, Golgi apparatus, and mitochondria were extensive in the cytopl asm. TP administration to orchidectomized rats resulted in formation of les s extensive lipid droplets and mitochondria. In pinealectomized rats, golgi complex, mitochondria, and enlarged smooth endoplasmic reticulum were exte nsive in the cytoplasm of Leydig cells. Formation of cytoplasmic secretory granules and osmiophilic bodies was observed. Testicular weight increased c ompared to group IV. Melatonin decreased testicular weight in comparison to group V and prevented ultrastructural changes. Pinealectomy and orchidecto my caused hyperactivity in Leydig cells and pinealocytes, respectively, whi ch suggests a mutual relationship between the pineal gland and testis in th e rat.