Occurrence and localization of transforming growth factor-beta (TGF-beta 1, beta 2) during rabbit skin development

The expression of (TGF beta-1) and (TGF beta-2) in adult, fetal, and neonatal rabbit skin has been analyzed by immunohistochemistry. Samples were collected from the backs of fetal rabbits (23 and 30 days of gestation), newborn rabbits (1 day post-partum) and adult pregnant and nonpregnant rabbits. Forty samples were studied. To identify TGF-beta two antibodies were used: (RAB4) and (CL-B1/29). TGF-beta 1 and TGF-beta 2 displayed distinct distribution and intensity of staining at different stages of development. TGF-beta 1 was present in fetal skin (23 days of pregnancy) expressing abundant staining in cells within epidermis, dermis and hypodermis. Fetal skin (30 days of pregnancy) exhibited weak staining for TGF-beta 1; only isolated dermal cells in close proximity to hair follicles and sweat glands expressed intracellular staining. Newborn rabbit skin showed low expression for TGF-beta 1, around hair follicles and sweat glands. In contrast adult pregnant and non-pregnant rabbit skin exhibited abundant staining for TGF-beta 1 in epidermis, papillary dermis, around hair follicles, sweat glands, and blood vessels, no difference was observed among pregnant and non-pregnant rabbits. TGF-beta 2 was detected in all specimens and the distribution and intensity of staining were similar to those found for TGF-beta 1 in all groups. Our findings demonstrate that the expression of TGF-beta 1 and TGF-beta 2 is intense during early stages of rabbit skin development when morphogenesis is taking place and skin appendages are being formed; and less intense when these structures are formed and skin growth predominates. These results suggest an important role for TGF-beta 1 and TGF-beta 2 in rabbit skin development, probably regulating morphogenesis and growth.