Histological and immunohistochemical study of telocytes in the heart of male albino rats in different age groups

Background Telocytes (TCs) have been newly discovered as a type of interstitial cells in the heart. They have been suggested to have a role in cardiac renewal and repair. Aim To study the number and distribution of TCs in the heart of male albino rats and the effect of aging on their numbers. Materials and methods A total of 24 male albino rats were used in the present study. They were subdivided into four groups: group I included six rats that were 1 week old, group II included six rats that were 1 month old, group III included six rats that were 3 months old, and group IV included six rats that were 1 year old. Specimens were taken from both atria and ventricles and subdivided into two parts: a part processed and examined by light microscope and the other part processed and examined by electron microscope. CD117 and CD34 immunohistochemical stains were used for demonstration of sites, numbers, and distribution of TCs. Results By CD117 and CD34 immunohistochemical stains, there was a statistically significant increase in the number of TCs in atria more than in ventricles. Moreover, there was a significant decrease in the number of TCs with aging. In Masson's trichrome-stained sections, there was an increase in collagen fibers between cardiomyocytes and around the blood vessels with age. By electron microscopic examination, TCs appeared as branched spindle, triangular, or cubical cells with long processes (telopodes) arising from the cell body. Telopodes showed variation in diameter, which had a narrow part (podomer) and a dilated part (podom). They showed homocellular junction with another TC's telopodes and heterocellular junctions between TCs and cardiomyocytes; moreover, multivesicular bodies were also seen. Conclusion There was a decrease in the number of TCs in the heart together with minimal changes in its shape and structure with aging.