Apoptosis in human skin development: Morphogenesis, periderm, and stem cells

The study demonstrated that apoptosis was crucial in human skin development, particularly in the morphogenesis of the epidermis and its appendages. Embryonic and fetal-specific periderm cells and incompletely keratinized cells were replaced by differentiating keratinocytes to form a functional epidermis, with apoptosis involved in the deletion of these cells and remodeling of appendages. DNA fragmentation and transglutaminases indicated apoptosis, while the bcl-2 gene, associated with cell survival, was expressed in hair follicles and sweat glands, suggesting it might be a stem cell marker. The study highlighted that terminal differentiation of epidermal cells could be considered a specialized form of apoptosis.