Novel identification of telocytes in the skin of the desert tortoise (Testudo graeca): A correlative study using semithin section, transmission electron microscopy, and immunofluorescence

Abstract

This study comprehensively investigates the presence and characteristics of telocytes in the skin of desert tortoises, employing a multifaceted approach that includes light microscopy, transmission electron microscopy (TEM), and immunofluorescence analyses. A groundbreaking revelation is made as our study, for the first time, unveils the existence of telocytes in the skin of the Greek tortoise. The intricate architecture of the skin, comprising scales, a keratin layer, an epidermis, a dermis, and a hypodermis, is meticulously examined. The epidermis, marked by a stratified epithelium and a substantial keratin layer, features a corrugated basement membrane. Notably, the dermis is a significant site housing telocytes, identified by their distinctive rod-shaped morphology and extensive cytoplasmic processes, including a thick podom and a thin podomere containing nanovesicles. Extracellular nanovesicles play a crucial role in facilitating communication between telocytes and melanophores. Utilizing CD34, PDGFRα, and Vimentin markers, we observe the abundance and intensity of CD34, particularly in the central dermis, and the widespread presence of PDGFRα throughout the dermis. Although less abundant near the epidermis and hypodermis, Vimentin increases in the central dermis with reduced intensity compared to CD34 and PDGFRα. Co-expression analyses reveal robust associations between CD34 and PDGFRα, highlighting them as dominant markers in telocytes. This suggests their potential significance in supporting the tortoise's skin health and resilience in harsh desert conditions. The understanding of these molecular dynamics provides insights into the adaptive strategies employed by desert tortoises, emphasizing the therapeutic relevance of these markers in enhancing skin health in challenging environments.