Ultrastructural Study on Connective Tissue-Epithelial Junctions in Anagen Hair Follicle of Human Fetus

This study investigated the ultrastructural differences in connective tissue-epithelial junctions in anagen hair follicles of human fetuses. It found that the junctions around the dermal papilla and on the outside of the hair follicle differed significantly from those in the skin's dermoepidermal junction. Notably, structures such as hemidesmosomes, tonofilaments, attachment plaques, sub-basal dense plates, and anchoring filaments, which were present in the skin, were absent in the dermal papilla. The basal lamina was smoother, and collagen fibers were arranged orthogonally on the outside of the hair follicle, unlike in the dermal papilla. These findings suggested that the mechanical connection in hair follicles was weaker than in the skin, reflecting the dynamic nature of the anagen phase compared to the stable state of the epidermis.