part of part_of develops from male reproductive system 男性生殖系统 testis 睾丸 (...) while it is likely that Urbilateria lacked a complex somatic reproductive system, it is at present impossible to speculate on whether or not it possessed a true gonad, let alone any other somatic adaptations for reproduction (reference 1); Examination of different vertebrate species shows that the adult gonad is remarkably similar in its morphology across different phylogenetic classes. Surprisingly, however, the cellular and molecular programs employed to create similar organs are not evolutionarily conserved (reference 2).[uncertain][VHOG] A gonad of a male animal. A gonad produces and releases sperm. AAO:0000606 BILA:0000124 BSA:0000085 BTO:0001363 CALOHA:TS-1030 EFO:0000984 EHDAA2:0002007 EHDAA:8146 EMAPA:17972 EV:0100102 FBbt:00004928 FMA:7210 GAID:396 HAO:0001007 MA:0000411 MAT:0000132 MESH:D013737 MIAA:0000132 Male reproductive organ.[TAO] OpenCyc:Mx4rvVjM25wpEbGdrcN5Y29ycA TAO:0000598 The testes are descended in metatherian and eutherian mammals, first transabdominally, then inguinoscrotally UBERON:0000473 UBERON:0002117 UMLS:C0039597 VHOG:0000252 WBbt:0006794 XAO:0000157 ZFA:0000598 galen:Testis gonad of male genitalia gonad of male genitalia gonad of male reproductive system gonad of male reproductive system male gonad male gonad orchis orchis testes testes testicle testicle testicular testiculus testiculus uberon (...)虽然Urbilateria很可能缺少一个复杂的体细胞生殖系统，但目前不可能推测它是否拥有一个真正的性腺，更不用说任何其他体细胞适应繁殖(参考文献1)； 对不同脊椎动物种类的研究表明，成年生殖腺的形态在不同的系统发生分类中非常相似。然而令人惊讶的是，用来创造相似器官的细胞和分子程序并不是进化上保守的（参考文献2）。[uncertain][VHOG] 男性生殖器性腺 男性生殖器性腺 睾丸(orchis) 睾丸(orchis) 睾丸(testes) 睾丸(testes) 睾丸(testicle) 睾丸(testicle) 睾丸(testiculus) 睾丸(testiculus) 睾丸在亚热哺乳动物和真兽类中下降，先经腹，后经腹。 睾丸的 雄性动物的性腺。性腺产生并释放精子。 雄性生殖器官。[TAO] 雄性生殖系统性腺 雄性生殖系统性腺 雄性生殖腺 雄性生殖腺 gonad 性腺(gonad) reproductive organ 生殖器官 male reproductive organ 男性生殖器官 indifferent gonad 未分化性腺