part_of part of part of contained in develops from existence overlaps material entity anterior region of the whole animal dorsal region of the whole animal posterior region of the whole animal testis spermatogonium spermatocyte Planarian_Anatomy https://orcid.org/0000-0003-2569-1939 | https://orcid.org/0000-0002-7535-4407 PMID:27163480 PMID:25404302 PMID:22074376 PMID:27304889 PMID:17376870 PMID:25278423 PMID:20844018 PMID:29095551 A tektin-1+ male germ cell that develops from spermatogonia. The euploid primary spermatocytes undergo meiosis and give rise to the haploid secondary spermatocytes which in turn give rise to spermatids. PMID:27330085 CL:0000017 primary spermatocyte male germ cell prepharyngeal region parapharyngeal region tail region adult hermaphrodite copulatory region