OCCURRENCE AND LOCALIZATION OF TRANSFORMING GROWTH-FACTOR-BETA (TGF-BETA-1, BETA-2) DURING RABBIT SKIN DEVELOPMENT

The expression of (TGFbeta-1) and (TGFbeta-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-beta1 and TGF-beta2 displayed distinct distribution and intensity of staining at different stages of development. TGF-beta1 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-beta1; only isolated dermal cells in close proximity to hair follicles and sweat glands expressed intracellular staining. Newborn rabbit skin showed low expression for TGF-beta1, around hair follicles and sweat glands. In contrast adult pregnant and non-pregnant rabbit skin exhibited abundant staining for TGF-beta1 in epidermis, papillary dermis, around hair follicles, sweat glands, and blood vessels, no difference was observed among pregnant and non-pregnant rabbits. TGF-beta2 was detected in all specimens and the distribution and intensity of staining were similar to those found for TGF-beta1 in all groups. Our findings demonstrate that the expression of TGF-beta1 and TGF-beta2 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-beta1 and TGF-beta2 in rabbit skin development, probably regulating morphogenesis and growth.