Figure 3.

Cynomolgus monkey model revealed defective spermatogenesis and abnormal sperm morphologies in the Ssx1-KD testes

(A) H&E staining of testicular tissue sections obtained from male cynomolgus monkeys. Compared to the regular arrangement of various germ cells in the testes from the NC group, spermatogenic defects, including loss or misarranged germ cells, were observed in the testes from Ssx1-KD male cynomolgus monkeys; spermatogonia (red arrowheads), spermatocytes (blue arrowheads), round spermatids (yellow arrowheads), and spermatozoa (black arrowheads). Scale bars: 50 μm.

(B) Abnormal morphologies were also observed in the sperm from Ssx1-KD male cynomolgus monkeys, including coiled (ii, iii), bending (iv), and absent (v) flagella. Scale bars: 5 μm.

(C) Compared to the typical “9 + 2” microtubule structures in the sperm flagella of the NC group (i and iv), Ssx1-KD in the testes also led to various ultrastructural abnormalities in the sperm flagella, including the misarranged or missing ODFs (iii, v, and vi) and the loss of DMTs or CP (ii, iii, v, and vi). Scale bars: 200 nm. Abbreviations: CP, central pair of microtubules (red arrows); DMT, peripheral microtubule doublet (blue arrows); ODF, outer dense fiber (yellow arrows).

(D) Ssx1-KD in the testes of male cynomolgus monkeys led to temporary abnormalities in sperm motility and morphology after injections. The values for the NC group represent three repeated statistical analyses of one cynomolgus monkey, and the values for Ssx1-KD group represent the mean data from three male cynomolgus monkeys. For each cynomolgus monkey, at least 200 spermatozoa were examined to evaluate the rates of morphologically abnormal spermatozoa.