Sperm-oviduct interaction: Differential gene expression of growth factors induced by sperm DNA fragmentation

The presence of sexed sperm in bovine oviduct epithelial cells alters the protein profile related to stress and immune response

Although sperm sexing technology has progressed considerably in the last decade, there are still challenges to fully understand the reason for the low fertility of sexed sperm. Thus, we aimed to evaluate the effect of sexed and non-sexed sperm on the proteome of bovine oviduct epithelial cells (BOECs). Semen from six Nellore bulls was used and one ejaculate from each bull was collected and separated into three fractions: non-sexed, sexed for X-sperm and sexed for Y-sperm. Previously synchronized females were artificially inseminated with either a pool of non-sexed sperm from 6 sires (NS), or a pool of sexed X and Y sperm from 6 sires (XY) or saline solution (Control). After insemination, animals were slaughtered and oviducts were collected to obtain BOECs samples, which were used for proteomic analysis. The results revealed that the oviductal response on isthmus region to the presence of sperm is different when sexed and non-sexed sperm are used. Sexed sperm seemed to induced a more intense and imbalanced response to several processes, such as oxidative and heat stress, immune response and movement of the oviduct muscle.

How sperm protects itself: A journey in the female reproductive system

Sperm must pass a complex route in the female reproductive tract (FRT) to reach the fertilization site and join the oocyte. Thus, it should employ several mechanisms to survive against the female immune system, fertilize the oocyte, and successfully transmit paternal genes to the next generation. In addition to self-protection, sperm may be involved in the immune tolerance to the developing embryo and regulating the FRT for embryo implantation and subsequent pregnancy. Hence, this review intends to summarize the mechanisms that protect sperm in the FRT: including immunomodulatory factors that are carried by seminal plasma, cell-to-cell and molecular interaction of sperm with epithelial and immune cells of the FRT, high regulated secretions of inflammatory factors such as cytokines, chemokines, and growth factors, inducing immune tolerance to paternal antigens, and specialized expression of cell receptors and binding proteins. In most of these events sperm induces the FRT to protect itself by modulating immune responses for its own benefit. However, not all sperm in the semen are able to trigger the survival mechanisms and only high-quality sperm will overcome this challenge. A clear understanding of the molecular mechanisms that maintain sperm viability and function in the FRT can lead to new knowledge about infertility etiology and a new approach in assisted reproductive technologies for the preparation and selection of the best sperm based on the criteria that physiologically happen in-vivo.

Functional Morphology of the Human Uterine Tubes in the 21st Century: Anatomical Novelties and Their Possible Clinical Applications

The uterine tube (UT) pathologies account for 25-35 % of female factor infertility. Although these peculiar organs were first studied several hundred years ago, they have become overlooked and neglected mainly due to the successes of reproductive medicine. Nevertheless, reproductive medicine still faces many challenges regarding the fertility outcomes of in vitro fertilization (IVF). Many obstacles and problems can be resolved by a more detailed understanding of the UT morphology and function during normal reproduction. Over the course of the 21st century, many new insights have been obtained: the presence of a population of telocytes in the tubal wall responsible for normal motility and hormone sensory function, the demonstration of lymphatic lacunae of the mucosal folds necessary for oocyte capture and tubal fluid recirculation, or a thorough profiling of the immune makeup of the UT epithelial lining with the discovery of regulatory T cells presumably important for maternal tolerance towards the semi-allogenic embryo. New discoveries also include the notion that the UT epithelium is male sex hormone-sensitive, and that the UT is not sterile, but harbors a complex microbiome. The UT epithelial cells were also shown to be the cells-of-origin of high-grade serous ovarian carcinomas. Finally, yet importantly, several modern morphological directions have been emerging recently, including cell culture, the development of tubal organoids, in silico modelling, tissue engineering and regenerative medicine. All these novel insights and new approaches can contribute to better clinical practice and successful pregnancy outcomes.