gonad 性腺(gonad) female gonad 雌性生殖腺 (...) 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] AAO:0000371 BILA:0000125 BSA:0000080 BTO:0000975 CALOHA:TS-0730 EFO:0000973 EHDAA2:0001360 EHDAA:8124 EMAPA:17962 EV:0100111 Either of paired female reproductive organs involved in production of ova and female sex hormones.[AAO] FBbt:00004865 FMA:7209 Female reproductive organ.[TAO] GAID:367 MA:0000384 MESH:D010053 MIAA:0000125 OpenCyc:Mx4rvVi9QJwpEbGdrcN5Y29ycA Ovaries of some kind are found in the female reproductive system of many animals that employ sexual reproduction, including invertebrates. However, they develop in a very different way in most invertebrates than they do in vertebrates, and are not truly homologous. Many of the features found in human ovaries are common to all vertebrates, including the presence of follicular cells, tunica albuginea, and so on. However, many species produce a far greater number of eggs during their lifetime than do humans, so that, in fish and amphibians, there may be hundreds, or even millions of fertile eggs present in the ovary at any given time. In these species, fresh eggs may be developing from the germinal epithelium throughout life. Corpora lutea are found only in mammals, and in some elasmobranch fish; in other species, the remnants of the follicle are quickly resorbed by the ovary. In birds, reptiles, and monotremes, the egg is relatively large, filling the follicle, and distorting the shape of the ovary at maturity. Amphibians and reptiles have no ovarian medulla; the central part of the ovary is a hollow, lymph-filled space. The ovary of teleosts is also often hollow, but in this case, the eggs are shed into the cavity, which opens into the oviduct. Although most normal female vertebrates have two ovaries, this is not the case in all species. In birds and platypuses, the right ovary never matures, so that only the left is functional. In some elasmobranchs, the reverse is true, with only the right ovary fully developing. In the primitive jawless fish, and some teleosts, there is only one ovary, formed by the fusion of the paired organs in the embryo TAO:0000403 UBERON:0000992 UMLS:C0029939 VHOG:0000251 XAO:0000258 ZFA:0000403 female organism genitalia gonad female organism genitalia gonada female organism reproductive system gonad female organism reproductive system gonada female reproductive system gonad female reproductive system gonada genitalia of female organism gonad genitalia of female organism gonada gonad of female organism genitalia gonad of female organism reproductive system gonad of female reproductive system gonad of genitalia of female organism gonad of reproductive system of female organism gonada of female organism genitalia gonada of female organism reproductive system gonada of female reproductive system gonada of genitalia of female organism gonada of reproductive system of female organism ovarian ovaries ovarium ovary ovum-producing ovary reproductive system of female organism gonad reproductive system of female organism gonada the gonad of a female organism which contains germ cells 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] 产卵卵巢 包含生殖细胞的雌性生物的性腺 卵巢 卵巢(ovaries) 卵巢(ovarium) 卵巢(ovary) 女性生殖器官。[TAO] 成对的雌性生殖器官中的任一个，参与卵子和雌性性激素的产生。 某些类型的卵巢存在于许多有性繁殖的动物的雌性生殖系统中，包括无脊椎动物。然而，它们在大多数无脊椎动物中的发育方式与在脊椎动物中的非常不同，并不是真正的同源。在人类卵巢中发现的许多特征对于所有脊椎动物来说都是常见的，包括卵泡细胞、白膜等的存在。然而，许多物种在它们的一生中比人类产生更多的卵，因此，在鱼和两栖动物中，在任何给定的时间，卵巢中可能存在数百个，甚至数百万的可育卵。在这些物种中，新鲜的卵可能在一生中都从生殖上皮发育而来。黄体只存在于哺乳动物和一些弹性棘鱼中；在其他物种中，卵泡的残余很快被卵巢再吸收。在鸟类、爬行类和单足类中，卵相对较大，充满卵泡，并在成熟时卵巢的形状发生扭曲。两栖动物和爬行动物没有卵巢髓质；卵巢的中心部分是一个中空的充满淋巴的空间。硬骨鱼的卵巢通常也是中空的，但在这种情况下，卵会掉进腔内，而腔内通向输卵管。虽然大多数正常的雌性脊椎动物有两个卵巢，但并非所有物种都是如此。在鸟类和鸭嘴兽中，右卵巢永远不会成熟，因此只有左卵巢才起作用。在一些软骨鱼类，相反的是，只有右卵巢充分发展。在原始无颚鱼和一些硬骨鱼中，只有一个卵巢，由胚胎中成对器官的融合而形成。 雌性生殖器官的生殖器 雌性生殖器官的生殖系统 雌性生殖系统性腺(female reproductive system gonad) 雌性生殖系统性腺(female reproductive system gonada) 雌性生殖系统的性腺(gonad of female reproductive system) 雌性生殖系统的性腺(gonada of female reproductive system) 雌性生殖腺的生殖系统 雌性生物体性腺生殖器 雌性生物体生殖器性腺(female organism genitalia gonad) 雌性生物体生殖器性腺(gonad of female organism genitalia) 雌性生物体生殖器性腺(gonad of genitalia of female organism) 雌性生物体生殖器性腺(gonada of female organism genitalia) 雌性生物体生殖器性腺(gonada of genitalia of female organism) 雌性生物体生殖系统性腺(female organism reproductive system gonad) 雌性生物体生殖系统性腺(female organism reproductive system gonada) 雌性生物体生殖系统性腺(gonad of female organism reproductive system) 雌性生物体生殖系统性腺(gonad of reproductive system of female organism) 雌性生物体生殖系统性腺(gonada of female organism reproductive system) 雌性生物体生殖系统性腺(gonada of reproductive system of female organism) 雌性生物生殖器性腺 reproductive organ 生殖器官