Uribe Mari Carmen, De la Rosa-Cruz Gabino, García-Alarcón Adriana
Laboratorio de Biología de la Reproducción, Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, México, DF, México.
J Morphol. 2014 Dec;275(12):1406-17. doi: 10.1002/jmor.20315. Epub 2014 Sep 15.
Intraluminal gestation, as it occurs in viviparous goodeids, allows a wide diversity of embryo-maternal metabolic exchanges. The branchial placenta occurs in embryos developing in intraluminal gestation when ovarian folds enter through the operculum, into the branchial chamber. The maternal ovarian folds may extend to the embryonic pharyngeal cavity. A branchial placenta has been observed in few viviparous teleosts, and there are not previous histological analyses. This study analysis the histological structure in the goodeid Ilyodon whitei. The moterno ovarian folds extend through the embryonic operculum and reach near the gills, occupying part of the branchial chamber. These folds extend also into the pharyngeal cavity. In some regions, the epithelia of the ovarian folds and embryo were in apposition, developing a placental structure in which, maternal and embryonic capillaries lie in close proximity. The maternal epithelium has desquamated cells which may enter through the branchial chamber to the pharyngeal cavity and the alimentary tract. The complex processes that occur in the ovaries of viviparous teleosts, and its diverse adaptations for viviparity, as the presence of branchial placenta, are relevant in the study of the evolution of vertebrate viviparity.
管腔内妊娠，就像在胎生的古氏鱼中发生的那样，允许胚胎与母体之间进行广泛多样的代谢交换。鳃胎盘出现在管腔内妊娠发育的胚胎中，此时卵巢褶皱通过鳃盖进入鳃腔。母体的卵巢褶皱可能延伸到胚胎的咽腔。在少数胎生硬骨鱼中观察到了鳃胎盘，但此前没有组织学分析。本研究分析了古氏鱼伊利奥顿白氏鱼的组织结构。母体的卵巢褶皱穿过胚胎的鳃盖并延伸到鳃附近，占据了鳃腔的一部分。这些褶皱也延伸到咽腔。在一些区域，卵巢褶皱和胚胎的上皮细胞相互紧贴，形成了一种胎盘结构，母体和胚胎的毛细血管紧密相邻。母体上皮细胞有脱落的细胞，这些细胞可能通过鳃腔进入咽腔和消化道。胎生硬骨鱼卵巢中发生的复杂过程，以及其对胎生的多样适应性，如鳃胎盘的存在，在脊椎动物胎生进化的研究中具有重要意义。
