COMPARATIVE HISTOLOGICAL STUDY OF CARDIAC TELOCYTES IN DIFFERENT AGES OF MICE AND THEIR ROLE IN HEART DEVELOPMENT Ibrahim K. Ragab & Esam O. Kamel Histology department, AL-Azhar Faculty of Medicine in Assiut
Background: Telocytes (TCs) make a network in the myocardial interstitium, which is involved in the long-distance intercellular signaling coordination. They are involved in heterocellular contacts with cardiomyocytes (CMs) and cardiac stem/progenitor cells. TC might play a role in myocardial development by guiding cardiac muscle precursor cells to form the correct three-dimensional myocardial architecture. Aim of the work: Is to identify TCs in mice myocardium at different developmental stages to investigate the occurrence of TCs in the developing heart and study their role during heart development. Material and Methods: 45 male mice of three different ages (3 months, 1 year and 2 years) (15 mice for each age group) were used. The hearts dissected out and specimens of left ventricles of each group were divided into two subgroups which processed for light and electron microscopic studies. Morphometrical and statistical studies were conducted. Results: By light microscopy, sections of myocardium of all groups showed branching CMs with central nuclei and acidophilic cytoplasm. Blood capillaries could be noticed. In sections of young and adult groups, minimal interstium and spindle, triangular or stellate shaped TCs could be observed in between the CMs. In sections of old group, the interstitium was increased and contained fibroblasts and collagen fibers and no TCs could be observed. The electron microscopy confirmed the light microscopic results and showed the ultrastructure of cardiac muscle fibers in all groups and TCs in young and adult groups only. Conclusion: cardiac TCs play an important role in the heart development in mice.