PDF《Duration》

Post-mating In?ammatory Responses of the Uterus T Katila Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Ma ¨ntsa ¨la ¨, Finland Contents This review attempts to summarize the current knowledge on uterine in?ammatory response after mating in horses, pigs and cattle.

Post-mating endometritis has been extensively studied in horses as it has been considered to cause infertility. The in?ammation is known to occur also in cattle, but it has not been investigated to a similar extent. There are a number of publications about mechanisms of post-mating uterine in?am- mation in pigs, which seem to resemble those in horses. The major focus of this review is the horse, but relevant literature is presented also on swine and cattle. Spermatozoa, seminal plasma and semen extenders play roles in the induction of in?ammation. In addition, sperm numbers, concentration and viability, as well as the site of semen deposition may modulate the in?ammatory response. Cytokines, polymorphonuclear leucocytes (PMN) and mononuclear cells represent the uterine in?ammatory response to mating. In?ammation is the ?rst line of defence against invasion and eliminates excess spermatozoa and bacteria. Semen deposition elicits a massive PMN inva- sion, followed by phagocytosis of sperm aided by the forma- tion of neutrophil extracellular traps. Exposure of the female genital tract to semen is important also for endometrial receptivity and pre-implantation embryo development. Semi- nal plasma (SP) and in?ammation elicit transient immune tolerance to antigens present in semen. SP contains immune- regulatory molecules that activate and control immune responses to antigens by stimulating expression of cytokines and growth factors and by initiating tissue remodelling. SP also regulates ovarian function. E?ective elimination of excess sperm and in?ammatory by-products and subsequent rapid return of the endometrium to the normal state is a prerequisite for pregnancy. Uterine back?ow, driven by myometrial contractions and requiring a patent cervix, is an important physical tool in uterine drainage. Introduction Billions of spermatozoa are ejaculated into the female genital tract to maximize the chances of fertilization, although only some thousands reach the oviduct. The selection of sperm takes place in di?erent compartments of the tract, but ultrastructurally normal viable sperma- tozoa are more likely to gain entrance to the oviduct. In most species, the utero-tubal junction (UTJ) is the main sperm reservoir, allowing slow release of sperm into the more cranial sections of the oviduct (reviewed by Rath et al. 2008). It is believed that in ruminants, the cervical crypts and grooves, aided by mucus, ?lter defective and immotile sperm, protect sperm from phagocytosis, act as safe storage areas and provide privileged paths for the transport of viable sperm (Mullins and Saacke 1989). However, it has not been shown that spermatozoa stored in the cervix enter the oviducts. In dogs and horses, spermatozoa were localized in uterine glands, albeit that most glands contained only a single sperma- tozoon (Rijsselaere et al. 2004;

Fiala et al. 2008). Yet, there is no evidence that sperm are released from the glands C it is more likely that they accessed these sites randomly. Porcine spermatozoa have been shown to bind to uterine epithelial cells su?ciently strongly to withstand vigorous ?ushing. It has been suggested that viable sperm adhere to epithelial cells and that this is part of the sperm selection processes in the female genital tract (Taylor et al. 2008). Equine spermatozoa were detected in the luminal epithelial cells 1C4 h after arti?cial insemination (AI), but the degree of binding was not determined (Fiala et al. 2010). The fate of the majority of sperm is elimination. Sperm cells are antigenic to females, and immunization against sperm can result in infertility. Rapid removal of sperm is thought to prevent acquired immune responses against sperm (Hansen 2011). Immune responses elicited by semen not only serve the purpose of rapid sperm elimination, but more importantly, the female tract immune response to semen results in functional immune tolerance to paternal antigens (Robertson 2007). Sperm Transport and Elimination are of Short Duration Neither transport nor elimination of spermatozoa takes long. The ?rst sperm have been found in the oviducts within minutes after mating, but these rapidly transported spermatozoa may not participate in fertilization (Rodri- guez-Martinez et al. 2010). The spermatozoa that enter the oviducts do so within