Basic fibroblast growth factor (bFGF) in rodent testis

We have previously described a 30 kDa basic fibroblast growth
factor (bFGF)-like protein in rodent testicular homogenates and
have shown that pachytene spermatocytes are the sites of
predominant immunoreactivity for this bFGF-like protein
(Mayerhofer, A., Russell, L.D., Grothe, C., Rudolf, M. and Gratzl,
M. (1991) Endocrinology 129, 921–924). We have now addressed the
question whether this 30 kDa bFGF-like protein is a large bFGF form
and whether it is produced by pachytene spermatocytes. We detected
bFGF mRNA in homogenates of isolated mouse spermatocytes (which
consisted mainly of pachytene spermatocytes) using S1 nuclease
protection assays. As shown by Western blot analyses, the bFGF mRNA
in mouse spermatocytes is translated into bFGF of an approximate
molecular weight of 30 kDa. Neither bFGF mRNA, nor bFGF itself, was
observed in isolated mouse Leydig cells. These results indicate
that the immunoreactive bFGF-like protein observed previously in
germ cells of the murine testis is identical to bFGF. Thus, germ
cells of the testis produce bFGF, which may exert regulatory
function in the process of spermatogenesis.