Figure 3. Prematurely developed low sperm count, occasional testes degeneration or vesicle enlargement observed in Fus1 KO but not in WT mice. (A) Sperm count in WT and Fus1 KO mice of different ages (6 m.o.: WT mice, n = 10, KO mice, n = 9; 11-12 m.o.: WT mice, n = 6; KO mice, n = 9) revealed a premature sperm count decrease in 11-12 m.o. Fus1 KO mice; (B) Unilateral (not shown) and bilateral testes degeneration (shown at x7.5 and x300 magnification) were observed occasionally in adult Fus1 KO but not in WT mice. Arrows point to a normal testis from a WT mouse and a degenerated one from a Fus1 KO mouse; (C) Enlargement of seminal vesicles, an aging lesion that occurs spontaneously in some mice aged 24 mo or older were found in Fus1 KO mice of 16-20 months old. Lesions of different types were observed: asymmetrical vesicle enlargement (left), a normal size vesicle is shown by the arrow; symmetrical enlargement and discoloration of vesicles (right); symmetrical vesicle enlargement (not shown).