Basic fibroblast growth factor-like substance in nuclei of male germ cells undergoing meiosis

The presence of a basic fibroblast growth factor-like immunoreactive substance was demonstrated in the nuclei of germ cells at stages from spermatocyte to spermatid in adult rat testis by using immunohistochemistry with an antibody raised against a synthetic peptide corresponding to residues 1-10 of bovine basic fibroblast growth factor [1-146]. The fluorescence was very weak in the nuclei and cytoplasm of spermatogonia, Sertoli cells, and most of the interstitial compartments, except for capillary endothelial cells. This is the first study to demonstrate the presence of basic fibroblast growth factor-like immunoreactive material in the nuclei of haploid cells in vivo.