Proliferating cell nuclear antigen in tissues and organs of human embryos

The expression of proliferating cell nuclear antigen (PCNA) was demonstrated in some organs in the course of the early intrauterine development. The high expression of PCNA was found in the primitive embryonic myocardium, lungs, primitive gut, liver, pancreas, in the area of "neogene zone" of metanephros (primitive kidney), in the narrow surface zone of the primitive adrenal cortex and in the surface coeloma epithelium, in medullary strips and in the mesenchyme surrounding gonads.