LOCALIZATION OF S-100 PROTEIN IN PIG OVARIAN STRUCTURES

Distribution of S-100 protein in porcine ovaries was revealed by an ap plication of polyclonal antibodies against S-100 protein and PAP unive rsal kit to formalin-fixed, paraffin-embedded tissues. The presence of S-100 protein was demonstrated in follicular cells of all ovarian fol licles (including their atretic forms), with a decrease in intensity o f the reaction parallel to an increase in follicle size. No reaction w as found in oocytes, regardless of the developmental stage of the foll icle. Weak expression of S-100 protein was observed in theca interna c ells of mature follicles and in the youngest generation of theca-lutei n cells of the corpus luteum. A distinctly positive reaction was also observed in groups of cells resembling hilus cells as well as in endot helia of arteries and some capillaries. Results are compared with data concerning the localization of S-100 protein in human and bovine ovar ies. Possible relationship between the presence of S-100 protein and t he level of cellular differentiation is discussed.