Electron Microscopy and Immunohistochemistry using Indicators of Apoptosis and Proliferation on Guinea Pig Parathyroid Gland

Abstract

Maintenance of blood calcium level depended on the parathyroid hormone secretion that released from the parathyroid gland which important for bone mineralization. This work aimed to investigate the ultrastructure and immunohistochemical reaction of parathyroid gland of Guinea pig. The study was carried out on twenty five healthy male Guinea pigs, sixty days prenatal, one month postnatal and twelve months postnatal. Parathyroid gland consisted of fibrous capsule and cellular parenchyma which included chief and oxyphil cells. Ultrastructuraly, parathyroid gland contained several chief cells, fibroblast and blood capillaries. Chief cells included two types; granulated and vacuolated. The granulated cells contained several organelles and different sizes of secretory granules. The vacuolated cells contained few organelles and several vacuoles. The organelles involved mitochondria, Golgi complex, lysosome and different shapes of RER. Immunohistochemical studies were done using caspase3 and Bax as marker for apoptosis. Bax was responsible for activation of caspase3 via mitochondrial pathway of apoptosis. PCNA and Ki-67 were used as markers for cell proliferation. Ki-67 reacted during different stages of cell cycle and increased in S-phase. PCNA reacts mainly in S-phase of cell cycle, indicating condensation of DNA in the nucleus. Immunohistochemical staining with PCNA and Ki-67 shows negative and positive nuclear reaction at early life, then cells tend to increase their nuclear reaction with age. Caspase3 showed a faint cytoplasmic reaction at early life and that increased gradually with age. Bax showed a positive reaction in the cytoplasm and increased with age.