Topographical and Developmental Studies on Target Sites of 1,25 (OH)₂ Vitamin D₃ in Skin

In the 1984 study, tritium-labeled 1,25 (OH)₂ vitamin D3 was used to identify target sites in the skin of vitamin D-deficient rats, including adult males, neonates, and pregnant females with their fetuses. The study found that this form of vitamin D3 was concentrated in the nuclei of cells in the outer root sheath of the hair and various layers of the epidermis, but not in the dermal papilla or connective tissue of the dermis. A distinct pattern of labeled cells was observed in developing hair of fetal rats, indicating a sequential induction of receptors. The study concluded that 1,25 (OH)₂ vitamin D3 has differential effects on skin structures and may predominantly affect cell differentiation. The number of rats involved in the study was 6 adult males, 6 neonates, and 3 pregnant females with their fetuses.