The frequency and morphology of "giant spermatogonia" in the human testis.

Giant spermatogonia (GS) characteristically appear singly between their normal counterparts. Their cytoplasm is clear by light microscopy and their ovoid nuclei, measuring at least 13 micron in diameter, contain homogeneously distributed chromatin. These cells were described originally in the last century and were interpreted as isolated physiological giant cells of the sexual epithelium (Stieve 1930). In our own study we found GS in the normal testis at an average frequency of 0.65/50 tubules. GS occur at the same frequency in testicular tissue surrounding germ cell tumors and in biopsy specimens from men with impaired fertility, except in the so-called mixed atrophy of the testis where increased numbers of GS per tubule are found. Ultrastructurally, GS are distinguishable from normal spermatogonia, from atypical germ cells and from seminoma cells. In addition, we found several distinct ultrastructural differences between GS and cells of pre-spermatogenesis as reviewed in the literature.