Abstract:
The ultrastructural interrelationship between the pineal gland and testis was evaluated in the rat. Wistar
rats were divided into 6 groups. Groups I and II were sham-orchidectomized and orchidectomized rats,
respectively. Rats in group III were orchidectomized and daily injected with testosterone propionate
(TP) for 1 month. Groups IV and V were sham-pinealectomized and pinealectomized, respectively.
Group VI was pinealectomized and daily injected 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 specimens were examined by
electron microscopy. Orchidectomy caused an increase of lipid droplets, cytoplasmic dense bodies, and
lysosomes. Rough endoplasmic reticulum, Golgi apparatus, and mitochondria were extensive in the
cytoplasm. TP administration to orchidectomized rats resulted in formation of less extensive lipid droplets
and mitochondria. In pinealectomized rats, golgi complex, mitochondria, and enlarged smooth
endoplasmic reticulum were extensive in the cytoplasm of Leydig cells. Formation of cytoplasmic
secretory granules and osmiophilic bodies was observed. Testicular weight increased compared to group
IV. Melatonin decreased testicular weight in comparison to group V and prevented ultrastructural changes.
Pinealectomy and orchidectomy caused hyperactivity in Leydig cells and pinealocytes, respectively,
which suggests a mutual relationship between the pineal gland and testis in the rat.
