A comparison of seminiferous tubules in normal control (A–D), nectin-2-/- (E–H), and nectin-3-/- mice (I–O) at the representative stages shown in period acid-Schiff–hematoxylin (PAS-H) staining (A–B, E–F, I–J), IHC for nectin-2 (red; C, G, K) and nectin-3 (red; D, H, L), and double IHC for SYCP3 (red) and GATA4 (green) in combination with PNA-lectin histochemistry (green) (M–O). Nuclei were stained with DAPI (blue; C–D, G–H, K–L, M–O). (A–L) Normal (A, E) and distorted (I) shapes of step 13 spermatids in stage I; abundant (B), fewer (F), and scarce (I) numbers of step 16 spermatids in stage VII; the presence (C, K) and absence (G) of nectin-2-immunoreactivity in Sertoli cells in stage I, as well as the presence (D, H) and absence (L) of nectin-3-immunoreactivity in step 13 spermatids in stage I. (M–O) Stage VII (M), VIII (N), and IX (O) seminiferous tubules were distinguishable with the help of SYCP3 immunoreactivity in preleptotene (PI) spermatocytes at stage VIII, but not in those at stage VII, in leptotene (L) spermatocytes at stage IX, or in pachytene (P) spermatocytes at stages VII–IX, even in the absence of step 16 spermatids (S16) and with similar acrosomal patterns in step 7–9 spermatids (S7-9). Se, Sertoli cells immunopositive for GATA4 (green). Scale, 20 μm (A-–L), 10 μm (M–O).