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

This study examined the ultrastructural differences in connective tissue-epithelial junctions in anagen hair follicles of human fetal scalp skin. It found that the junctions around the dermal papilla and on the outside of the hair follicle differed significantly from those in the dermoepidermal junction of the skin. 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 orthogonally arranged on the outside of the hair follicle, unlike in the dermal papilla. These findings suggested that the mechanical connection between the hair follicle and connective tissue was weaker than in the skin, reflecting the dynamic nature of the anagen phase compared to the stable state of the epidermis.