Peroxisomes are present in murine spermatogonia and disappear during the course of spermatogenesis.

Peroxisomes are organelles that are almost ubiquitous in eukaryotic cells. They have, however, never been described in germ cells within the testis. Since some peroxisomal diseases like Adrenoleukodystrophy are associated with reduced fertility, we have re-investigated the peroxisomal compartment of the germinal epithelium of mice using in situ hybridization, immunohistochemistry, Western blotting and immunoelectron microscopy. Within the seminiferous tubules, peroxisomes are present in Sertoli cells and in germ cells. We could show that small-sized peroxisomes of typical ultrastructure are concentrated in spermatogonia and disappear during the course of spermatogenesis. Peroxisomes of spermatogonia differ in their relative protein composition from previously described peroxisomes of interstitial cells of Leydig. Since germ cells differentiate in mouse testis in a synchronized fashion, the disappearence of peroxisomes could be a suitable model system to investigate the degradation of an organelle as part of a physiological differentiation process in higher eukaryotes.