Laboratorio de Histología y Embriología Descriptiva, Experimental y Comparada (LHYEDEC), Facultad de Ciencias Veterinarias (FCV), Universidad Nacional de La Plata (UNLP), Buenos Aires, Argentina.
Laboratorio de Biología de la Reproducción Animal, Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México, México.
J Morphol. 2021 Apr;282(4):533-542. doi: 10.1002/jmor.21326. Epub 2021 Feb 3.
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: (a) tunica mucosa; (b) tunica muscularis; and (c) 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, that is, (a) the control of the luminal diameter in the limit to the germinal region of the ovary by the presence of a cervix; (b) during insemination the gonoduct receives the spermatozoa, may store and transport them to the germinal region; (c) the presence of melano-macrophage centers indicates support of immunological processes, especially during gestation when these centers increase in size; (d) production of exocrine secretions; and (e) it is the birth canal, internally lined by an ciliated epithelium and surrounded by smooth musclesboth tissues supposedly supporting the birth process.
在胚胎发生过程中，硬骨鱼类的雌性不发育缪勒氏管，而缪勒氏管在所有其他脊椎动物中形成输卵管。因此，当它们达到性成熟时，它们没有输卵管。在胎生硬骨鱼类中，缺乏输卵管意味着胚胎的发育是在卵巢内进行的，这在脊椎动物中是独一无二的。卵巢是一个不成对的中空器官，其腔与尾部的生殖管相连，生殖管的特点是没有生殖细胞，生殖管在生殖孔处与外部相通。在所有生殖阶段，生殖管作为卵巢生殖区与外部之间的屏障发挥着重要作用。本研究描述了胎生硬骨鱼类 Cnesterodon decemmaculatus 的生殖管在非妊娠（卵黄前发生和卵黄发生）和妊娠期间的功能形态。使用组织学技术处理卵巢，并使用苏木精-伊红和过碘酸希夫染色。生殖管有两个区域：头部和尾部，由三个组织学层组成，从内到外依次为：（a）黏膜层；（b）肌层；和（c）浆膜层。在头部区域，有黏膜褶皱延伸到管腔中，形成类似于宫颈的结构。生殖管的组织学表明其具有重要功能，即：（a）通过宫颈的存在控制输卵管限制卵巢生殖区的管腔直径；（b）在授精期间，生殖管接收精子，可以储存和将其运输到生殖区；（c）黑色素巨噬细胞中心的存在表明支持免疫过程，特别是在妊娠期间，这些中心会增大；（d）分泌外分泌液；和（e）它是产道，内部衬有纤毛上皮，周围环绕着平滑肌，这两种组织都支持分娩过程。
