FIG. 2.

Phenotype of germ cells in nectin-2^−/− mice. (A and B) Photomicrograph of sperm from the epididymides and vasa deferentia of nectin-2^+/+ (A) and nectin-2^−/− (B). mice. Mutant sperm have nuclei with irregular shapes and prominent vesicles, as well as undulate tails. (C) Flow-cytometric analyses of spermatozoa stained with propidium iodide. Only the peak corresponding to 1N cells is present. (D to G) Photomicrographs of paraffin-embedded, hematoxylin- and eosin-stained sections of testes from nectin-2^−/− mice depicting different stages of the cycle of the seminiferous epithelium, identified by applying classical criteria (32). Present are Sertoli cells, primary spermatocytes, and spermatids at different stages of spermiogenesis: stage IX with normal preleptotene spermatocytes (s), pachytene spermatocytes (s), and step 9 spermatids (arrowed 9) (D); stage XI with normal preleptotene (lower layer) and pachytene (s, middle layer) spermatocytes but aberrant step 11 spermatids (arrowed 11, top left) (E); stage VI with normal spermatids at step 6 (arrowed 6, middle layer) and abnormal spermatids at step 15 (arrowed 15, upper layer), depicting aberrant nuclear shape (top right) (F); and stage VI with normal step 6 spermatids (arrowed 6, bottom) and abnormal step 15 spermatids (arrowed 15, upper layer (G). The latter cells exhibit aberrant nuclear shape and translucent vesicles. Magnifications, ×770 (A), ×684 (D to F), and ×1,995 (G).