FIGURE 4.

The mitochondrial phenotype changes with spermatogonial maturation. A, Seminiferous chord from 8-week-old pig testis (TEM; white arrow indicates spermatogonia, blue arrow basements indicate membrane, scale bar 2 μm). B, Seminiferous chord from 8-week-old pig testis (IHC for TOMM-20 (red), UCH-L1 (green), white arrows indicate spermatogonia with unilaterally accumulated mitochondria, scale bar 2 μm). C, Late prepubertal (8-week-old pig) spermatogonium (orange outline; TEM; white arrow indicates mitochondria, blue arrow basements indicate membrane, scale bar 2 μm). D, Late prepubertal (8-week-old pig) spermatogonium IHC for TOMM-20 (red), UCH-L1 (green), white arrow indicates unilaterally accumulated mitochondria, scale bar 2 μm). E, Mitochondria in late prepubertal (8-week-old pig) spermatogonia (TEM, red arrow heads indicate mitochondria associated membranes, scale bar 100 nm). F, Mitochondria in late prepubertal Sertoli cell (white arrow shows elongated mitochondria, scale bar 100 nm). G, Late prepubertal spermatogonia (8 weeks, orange) have lower oxygen consumption rate (OCR) than early prepubertal spermatogonia (1 week, green) (representative illustration of one biological replicate for OCR assay with the Seahorse Flux Analyzer, mean ± SD, n = 10 technical replicates); quantification shown as mean ± SEM, basal respiration (P = .0293, n = 3); maximum respiration capacity (P = .0155, n = 3); mitochondrial ATP production (P = .056, n = 3) (two-tailed, unpaired Student’s t test)