Spermatidogenesis is the creation of spermatids from secondary spermatocytes. They had gonads with oogonia, spermatogonia and spermatocytes. The spermatid is the haploid male gametid that results from division of secondary spermatocytes. These divide and differentiate into spermatocytes, which undergo meiosis to form spermatids. Some of these cells stop proliferation and differentiate into primary spermatocytes. Mutations in leptotene spermatocytes can result in premature chromosome condensation. After meiosis I, two secondary spermatocytes are formed. There are two types of spermatocytes, primary and secondary spermatocytes (Figure 1). Alternatively, they go on to differentiate into spermatocytes, spermatids and finally spermatozoa. "Type B spermatogonia" undergo mitosis to produce diploid intermediate cells called primary spermatocytes. The two secondary spermatocytes undergo the second meiotic division to form four haploid spermatids. Primary spermatocytes are diploid (2N) cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes. FSH stimulates primary spermatocytes to undergo the first division of meiosis, to form secondary spermatocytes. Recombinant-defective mutations can occur in "Spo11", "DMC1", "ATM" and "MSH5" genes of spermatocytes.