Silva, J.F. da et al. 2014. The middle - piece agenesis of spermatozoa: A defect of spermiogenesis. Pesquisa Agropecuaria Brasileira. 12, 1 (Apr. 2014), 247–250. DOI:https://doi.org/10.1590/S1678-3921.pab1977.v12.16849.