RESUMO
The objectives of this work were to describe some morphometric characteristics and to establish quantitative parameters of different regions of the equine oviductal mucosa from the isthmus, ampullary-isthmic junction (AIJ), and ampulla. Twenty-one mixed-bred mares were used for this study. Mares were selected in the following reproductive phases: anestrus, estrus, and diestrus. The left oviducts were examined with light microscopy, and rights ones were studied through the intraoviductal molds. The isthmus showed the smallest luminal area, mucosal area, epithelial perimeter, and luminal diameter. On the molds surfaces, some grooves extended as longitudinal canals, reducing their depth as they approached to the AIJ. Several small height projections, some obliquely positioned towards utero-tubal junction, were observed in all reproductive phases. These formations may represent pockets or cul-de-sacs in the basal areas of the epithelial folds. The AIJ mucosa gradually changed from the smooth isthmic region toward highly folded ampulla. The number and complexity of epithelial folds showed moderate increase in the same way that many of the morphometric parameters. Multiple curves were observed on the molds of the AIJ, creating a zigzag path in the oviductal lumen. In the ampulla, the high branched epithelial folds occupied most of the lumen, leaving a small luminal area free. A linear relationship between epithelial perimeter and mucosal area was found. The presence of glandular-like structures was observed in all the reproductive stages studied. The equine endosalpinx reveals a highly complex tridimensional arrangement where each region shows very particular and specific designs.
Assuntos
Mucosa/anatomia & histologia , Oviductos/anatomia & histologia , Reprodução/fisiologia , Animais , Feminino , Cavalos , Microscopia Eletrônica de Varredura , Mucosa/fisiologia , Oviductos/fisiologiaRESUMO
Members of TGF-ß superfamily play a major role in the endometrial changes involved in the establishment and maintenance of pregnancy. Their deregulated expression and action could lead to absolute or partial failure of embryo implantation. Nonetheless, the precise function and mechanism of many of these cytokines remain unclear. Nodal, a transforming growth factor beta (TGF-ß) superfamily member, was characterized in the human and rodent uterus and implicated in the tissue remodeling events during menstruation and embryo implantation. In order to study its possible role in the cattle reproductive process, we have analyzed Nodal expression pattern and localization in the oviduct and uterine horn during the oestrus cycle and early pregnancy (day 20). Nodal was detected both in oviduct and uterus during either the oestrus cycle or pregnancy; however, it shows a differential expression profile in the uterine horn at dioestrus and pregnancy, decreasing 1.5 and 1.4 folds in comparison with oestrus. Nodal immunostaining intensity was observed in stromal and in epithelial cells of the surface and the glandular epithelium. The staining pattern correlates with the RT-qPCR expression profile. This work is the first to evidence the presence of Nodal in the bovine reproductive tract; our data suggest that Nodal is a novel cytokine that would be involved in the remodelling occurring in the endometrium of cattle during the oestrus cycle and in the embryo implantation. The identification of new molecules that participate in endometrium cycling and/or pregnancy may be useful for predicting the ability of the uterine tissue to establish and maintain pregnancy or for detecting the infertility processes. These results highlight Nodal as a possible novel marker of the fertility process, nevertheless further studies should be done to determine its role in the reproductive system.
Assuntos
Ciclo Estral/metabolismo , Proteína Nodal/metabolismo , Oviductos/metabolismo , Útero/metabolismo , Animais , Bovinos , Ciclo Estral/genética , Feminino , Idade Gestacional , Imuno-Histoquímica , Proteína Nodal/genética , Gravidez , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de SinaisRESUMO
In mammals, fertilization and preimplantation embryo development occurs in the oviduct. Cross-talk between the developing embryos and the maternal reproductive tract has been described in such a way as to show that the embryos modulate the physiology and gene expression of the oviduct. Different studies have indicated that transforming growth factor beta (TGF-ß) can modulate the oviductal microenvironment and act as an autocrine/paracrine factor on embryo development. LEFTY2, a novel member of the TGF-ß superfamily is involved in the negative regulation of other cytokines in this family such as nodal, activin, BMPs, TGF-ß1 and Vg1. In previous studies, we have reported that LEFTY2 is differentially expressed in the rat oviduct during pregnancy. In this study, we describe the temporal pattern of LEFTY2 in pregnant and non-pregnant rat oviduct by western blotting, which showed higher levels of LEFTY2 on day 4 of pregnancy, a time at which the embryos are ending their journey along the oviduct. The cellular location of LEFTY2 was assessed by immunohistochemistry, which showed immunolabelling in the cytoplasm and at the apical surface of the oviductal epithelial cells. The oviductal fluid also presented a 26 kDa band, which corresponds to the biologically active form of this protein, at the preimplantation period of pregnancy, indicating LEFTY2 secretion to the lumen. As LEFTY2 is expressed at a high level just before the embryos pass to the uterus, its biological effect might be relevant and significant for the preimplantation stage of embryo development in the oviduct. The fact that embryos do not express LEFTY2 at this stage of development supports this hypothesis.