During embryogenesis, teleost females do not develop Müllerian ducts, which form the oviducts in all other vertebrates. Thus, when they reach sexual maturity they do not have oviducts. In viviparous teleosts, the lack of oviducts means that the development of the embryos occurs as an intraovarian gestation, unique among vertebrates. The ovary is an unpaired hollow organ whose cavity is continuous with the caudal portion, the gonoduct, characterized by the absence of germinal cells, which opens to the exterior at the gonopore. The gonoduct attains essential function as a barrier between the germinal region of the ovary and the exterior during all reproductive stages. This study describes the functional morphology of the gonoduct in the viviparous teleost Cnesterodon decemmaculatus during non-gestation (previtellogenesis and vitellogenesis) and gestation. The ovaries were processed using histological techniques and stained with hematoxylin-eosin, and periodic acid Schiff. The gonoduct has two regions: cephalic and caudal, and is formed by three histological layers, which are, from inside to the periphery: 1) tunica mucosa; 2) tunica muscularis; and 3) tunica serosa. In the cephalic region there are mucosal folds extending into the lumen and forming a structure similar to a cervix. The histology of the gonoduct indicates essential functions, i.e.,i) the control of the luminal diameter in the limit to the germinal region of the ovary by the presence of a cervix; ii) during insemination the gonoduct receives the spermatozoa, may store and transport them to the germinal region; iii) the presence of melano-macrophage centers indicates support of immunological processes, especially during gestation when these centers increase in size; iv) production of exocrine secretions; and v) it is the birth canal , internally lined by an ciliated epithelium and surrounded by smooth musclesboth tissues supposedly supporting the birth process. .

中文翻译：

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胎生 TELEOST Cnesterodon decemmaculatus (JENYNS, 1842) (POECILIDAE) 的性腺结构

在胚胎发生过程中，硬骨雌性不发育苗勒管，苗勒管形成所有其他脊椎动物的输卵管。因此，当他们达到性成熟时，他们没有输卵管。在胎生硬骨鱼中，没有输卵管意味着胚胎的发育是卵巢内妊娠，在脊椎动物中是独一无二的。卵巢是一个未配对的中空器官，其腔与尾端部分（生殖管）连续，其特征是没有生殖细胞，生殖细胞在生殖孔处向外部开放。在所有生殖阶段，性腺作为卵巢生发区和外部之间的屏障，发挥着重要的作用。本研究描述了非妊娠期（卵黄发生前和卵黄发生）和妊娠期间胎生硬骨鱼 Cnesterodon decemmaculatus 的性腺功能形态。使用组织学技术处理卵巢并用苏木精-伊红和高碘酸希夫染色。性腺分为头部和尾部两个区域，由三个组织层组成，从内到外：1）粘膜；2) 肌层；和 3) 浆膜。在头侧区域有粘膜皱襞延伸到管腔中并形成类似于子宫颈的结构。性腺的组织学表明其基本功能，即，i）通过子宫颈的存在控制在卵巢生发区域限制内的管腔直径；ii) 在受精过程中，生殖管接收精子，可以储存和运输它们到生发区；iii) 黑色素-巨噬细胞中心的存在表明对免疫过程的支持，尤其是在这些中心规模增加的妊娠期间；iv) 外分泌物的产生；v) 它是产道，内部衬有纤毛上皮并被平滑肌和据称支持分娩过程的组织包围。. 内部由纤毛上皮排列并被平滑肌包围，这两种组织据说都支持出生过程。. 内部由纤毛上皮排列并被平滑肌包围，这两种组织据说都支持出生过程。.