Campuzano-Caballero Juan Carlos, Uribe Mari Carmen
Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, DF 04510.
J Morphol. 2014 Mar;275(3):247-57. doi: 10.1002/jmor.20200. Epub 2013 Dec 18.
Female teleosts do not have oviducts because Müllerian ducts do not develop. Instead, the caudal region of the ovary, the gonoduct, connects to the exterior. Because of the lack of oviducts in viviparous teleosts, the embryos develop in the ovary, as an intraovarian gestation, unique in vertebrates. This is the first study to address the histology of the gonoduct in a viviparous teleost. The gonoduct of Poecilia reticulata was analyzed during previtellogenesis, vitellogenesis, and gestation. The gonoduct lacks germinal cells. From deep to superficial, the wall has simple cuboidal or columnar epithelium, loose connective tissue, longitudinal layer of smooth muscle, and visceral peritoneum. Cells of the immune system occur in the lumen and in the mucosa. The gonoduct was divided in three regions: 1) cephalic, 2) middle, and 3) caudal. At the initial part of each region, thin mucosal folds extend into the lumen. The cephalic region forms a tubular structure with light and irregular folds. The middle region has a wider lumen and is more irregular due to ventral invaginations and irregular and short mucosal folds; beneath the epithelium there are melano-macrophage centers. The caudal region is delimited from the middle region by folds; however, they are thinner than these of the other regions. Ventral invaginations form exocrine glands, and the smooth muscle is thicker than in the other regions. During gestation, cells of the immune system are abundant; melano-macrophage centers become larger and the glands exhibit desquamated cells. These observations suggest roles of the gonoduct in reducing the diameter of the lumen; receiving sperm during vitellogenesis; producing secretions, more abundant during vitellogenesis; and in immunological activity throughout the reproductive cycle. The ciliated epithelium and the thick muscle of the caudal region may be involved during birth.
雌性硬骨鱼没有输卵管，因为苗勒氏管不会发育。取而代之的是，卵巢的尾部区域，即生殖导管，与外部相连。由于胎生硬骨鱼缺乏输卵管，胚胎在卵巢内发育，即卵巢内妊娠，这在脊椎动物中是独一无二的。这是第一项研究胎生硬骨鱼生殖导管组织学的研究。对网纹食蚊鱼的生殖导管在卵黄发生前期、卵黄发生期和妊娠期进行了分析。生殖导管缺乏生殖细胞。从深层到浅层，管壁有单层立方上皮或柱状上皮、疏松结缔组织、平滑肌纵层和脏腹膜。免疫系统的细胞出现在管腔和黏膜中。生殖导管分为三个区域：1）头部，2）中部，3）尾部。在每个区域的起始部分，薄的黏膜皱襞延伸到管腔内。头部区域形成一个具有浅色且不规则皱襞的管状结构。中部区域管腔更宽，由于腹侧内陷以及不规则且短的黏膜皱襞而更加不规则；上皮下方有黑素巨噬细胞中心。尾部区域通过皱襞与中部区域分界；然而，这些皱襞比其他区域的更薄。腹侧内陷形成外分泌腺，平滑肌比其他区域更厚。在妊娠期期间，免疫系统的细胞丰富；黑素巨噬细胞中心变大，腺体出现脱落细胞。这些观察结果表明生殖导管在减小管腔直径、在卵黄发生期接收精子、产生分泌物（在卵黄发生期更丰富）以及在整个生殖周期的免疫活动中发挥作用。尾部区域的纤毛上皮和厚肌肉可能在分娩过程中起作用。
