In spermatogenesis, during growth phase some spermatogonia either due to growth or due to food storage become 2 or 3 times larger of their original size and are known as primary spermatocytes, which undergo meiosis-I and as a result-2 haploid secondary spermatocytes are formed. Further, meiosis-II takes place that results in the formation of 4-spermatids. Then, these round, non-motile and haploid spermatids are transformed into thread-like motile, haploid sperms (four).