Fig. 2

TUNEL staining showing apoptosis of testicular cells and statistical analysis in different experimental groups. TUNEL staining indicated that the nucleus of apoptotic cells was green. In the YCG, positive staining was found only in Leydig cells; in the NAG, positive staining was found in spermatogonia, spermatocytes, sperm cells, and Leydig cells; and in the SWY1G and SWY2G, positive staining were found in spermatogonia and Leydig cells. Statistical analysis showed that the rate of apoptosis was significantly higher in the NAG than in the YCG (P < 0.01) and significantly lower in the SWY1G and SWY2G than in the NAG (P < 0.01). a: young control group (YCG); b: natural aging group (NAG); c: Heshouwuyin group 1 (SWY1G); d: Heshouwuyin group 2 (SWY2G). Each histogram represents the mean ± SD (n = 3). Columns with different letters represent significantly different values, while the same letters indicate no significant difference. Bar = 20 μm