Aim: The aim of this study was to investigate the pineal gland of rat at light and electron microscopic level.

Material and Method: For this purpose adult male Wistar albino rats were used. All animals were killed by vascular perfusion. The pineal glands of rats were removed, then processed for light and electron microscopy.

Results: It was observed that the pineal gland was externally covered by a capsule and also contained abundant capillaries. In parenchyma of the gland, the two main type of cells observed were pinealocytes and glial cells. These cells were differentiated according to their nuclear staining characteristics. The nucleus of pinealocytes was large, euchromatic and notched, their cytoplasm had mitochondria and rich from lipid droplets and also granular endoplasmic reticulum sacs, golgi complex and many ribosomes were observed. Glial cell nucleus was stained dark because of chromatin intensity, mitochondria, lipid droplets, rough endoplasmic reticulum sacs were present in the cytoplasm. These cells were observed to have cytoplasmic extensions.

Conclusion: Pinealocytes and glial cells were observed in the pineal gland of rat.