Fig. 4

sncRNA composition throughout sperm maturation. A Germ cells mature from spermatogonia at the basal membrane to immature spermatozoa inside the testis, which are then released from the tubules (green sperm). B As spermatozoa travel from caput (blue) to cauda (green), they receive input from the epididymis in the form of epididymosomes containing sncRNA. The table below shows the content of different sncRNA, during the transit of spermatozoa along the epididymis, namely decreasing levels of piRNA and increasing miRNA and tRNA-derived fragments (tRFs) down the cauda. Tomar et al. [172] recently discovered that mitochondrial-derived tRNAs (mtRNAs) are sperm-borne and enrich the spermatozoa as it travels down to cauda. Figure was adapted from Cheuquemán and Maldonado (2021) and created with Biorender.com