Figure 2.

Identification of primary spermatogonia. Both spermatogonia and Sertoli cells, isolated from the seminiferous tubules of 6-day-old mice, were transfected with two recombinant plasmids respectively: pSP without the antisense of Col1a1 fragment (a) and pSPAPI with the antisense of Col1a1 (b). About 10% of spermatogonia (arrowhead) expressed GFP fluorescence, while Sertoli cells (arrow) were negative. Flow cytometry analysis revealed that 93% of the GFP-positive cells were integrin-beta3 (marker for primordial germ cell) positive, suggesting that the green cells were indeed spermatogonia (c). SPG, spermatogonia.