DIFFERENCES IN P53 AND BCL-2 EXPRESSION IN RELATION TO CELL-PROLIFERATION DURING THE DEVELOPMENT OF HUMAN EMBRYOS

Aims - To study the patterns of p53 and Bcl-2 expression in relation t o cell proliferation during human embryogenesis in order to help eluci date their potential roles in the regulation of cell proliferation and apoptosis during morphogenesis. Methods - Immunohistochemistry for p5 3, Bcl-2, and proliferating cell nuclear cell antigen (PCNA) proteins was performed, using a variety of monoclonal antibodies, on paraffin w ax embedded sections of tissues from 68 human embryos and fetuses of b etween 4 and 30 weeks gestation. Results - Positive relations between sites of proliferative activity (as detected by PCNA expression) and p 53 expression were found in the kidney, early developmental stages of intestine and lungs, liver, pancreas, heart, and in embryonic osteobla sts. On the other hand, positive relations between proliferative activ ity and Bcl-2 expression were found in the gonads, adrenal glands, in the cells of the dental lamina, hair follicles, syncytiotrophoblast, c hondrocytes, and more advanced stages of intestinal development. In ti ssues of the central nervous system, p53 and Bcl-2 were co-expressed a t the same sites but there was an inverse relation between p53/ Bcl-2 expression and proliferative activity. Conclusions - These data sugges t that p53 and Bcl-2 have tissue specific and stage specific functions during embryogenesis.