Histological study on the effect of aging on the pineal gland of male albino rat

ABSTRACT

In the present study, it was found that the pineal gland of male albino rat consists of three types of cells; light pinealocytes, dark pinealocytes and neuroglial cells. The light cells are the dominant type of cells, their nuclei are large rounded and vesicular. They have slightly basophilic granular cytoplasm with one or two cellular processes. The dark cells are characterized by more basophilic cytoplasm. The neuroglial cells are smaller in size with deeply stained nuclei and the cytoplasm has numerous irregular large processes. In EM it was found that the light and dark cells have large nuclei with abundant euchromatin and prominent nucleoli. The cytoplasm of dark cells is more electron dense and both types contain abundant RER around the nucleus, large Golgi, many ribosomes, few lipid droplets and neurofilaments. There is a cell-to-cell contact at many sites. Both types of cells were considered active secretary cells. The neuroglial cells have irregular outlines and many branches that extend to surround the pinealocytes. The nucleus is large, dense and contains clumps of heterochromatin. With increasing age, there was an increase in the size of the cells. The pinealocyte nuclear membrane becomes deeply indented and the cytoplasm become more electron lucent and rarify from most of the all organoids except few mitochondria. The lipid contents increased. There was a deposition of many electron dense concretions both inter and intracellularly. The chemical nature of these concretions requires more histochemical studies. The neuroglial cells became very large in size and their cytoplasm became vacuolated. All the previous histological and ultras true tural changes of aged pineal gland of male albino rat represent a decline in the secretary activity of the gland