PDF《Duration》

8 h in ruminants, 1C2 h in swine (Rath et al. 2008) and 0.5C4 h in horses (Bader 1982;

Scott 2000). The elimination of sperm starts simultaneously with semen transport. Frequent uterine contractions, starting 5C10 min after mating, carry semen back and forth in the uterus. During this transuterine distribution, some sperm are not returned into the uterine horns but are drained through the cervix (Bourke and Lindsay 1988;

Katila et al. 2000;

Sumransap et al. 2007). The immediate uterine contractions after natural mating or AI are most likely initiated by mechanical stimulation of the vagina and cervix, which mediate neurogenic oxytocin (OT) release (Madill et al. 2000). Even the mere presence of a boar induces OT release, which promotes uterine activity (Langendijk et al. 2005). After the onset of myometrial contractions, the presence of large amounts of ?uid in the uterus may continue to stimulate contractions in the mare (Camp- bell and England 2004;

Sinnemaa et al. 2005). During the process of phagocytosis, PMNs release enzymes and prostaglandin (PG) F2a, which may contribute to increased uterine contractions observed 4C12 h after AI in mares (Troedsson et al. 1998). Reprod Dom Anim

47 (Suppl. 5), 31C41 (2012);

doi: 10.1111/j.1439-0531.2012.02120.x ISSN 0936-6768 ?

2012 Blackwell Verlag GmbH Oestrogens, PGs and OT are present in high concen- trations in seminal plasma (SP) of boars, stallions and bulls (Klausch and Kyank 1972;

Rei?steck et al. 1982;

Claus et al. 1987, 1992;

Watson et al. 1999). As oestro- gen concentrations are very high in SP of boars and stallions, it could be expected that intrauterine infusion of SP would increase uterine contractions in the females. However, SP did not increase uterine contractions of mares

10 min or

6 h after AI (Portus et al. 2005) and neither did it increase uterine activity of sows (Viring and Einarsson 1980a;

Langendijk et al. 2002). In the mare, most sperm are eliminated within

4 h and practically all within

12 h after AI, and only very few spermatozoa are detected at

24 h (Katila 1995;

Sinne- maa et al. 2005). Kaeoket et al. (2003c) detected marked numbers of spermatozoa in sows'

uteri 5C6 h after AI and moderate numbers 20C25 h in three of four sows. Small numbers of spermatozoa were recorded in the uterus

24 h after AI in pigs (Sumransap et al. 2007). In cattle, 60% of sperm are voided by

6 h after AI and by 12C24 h only a few per cent of sperm are left in the reproductive tract, the majority of which are found in the vagina (Mitchell et al. 1985;

Hawk 1987). Seminal Effects Semen consists of spermatozoa and SP, which play di?erent roles in the post-mating in?ammation. In AI, most SP is removed, which may alter the in?ammatory reaction. The insemination dose also includes semen extenders that di?er in composition and therefore in their in?ammatory e?ects. Spermatozoa induce leukocytosis Polymorphonuclear leucocytes are the ?rst cells to invade in?amed tissues. They are present in high numbers in blood and are rapidly recruited because of the kinetics of expression of leuko-endothelial adhesion molecules on leucocytes and endothelial cells. PMNs migrate following a chemo-attractant gradient initiated in the injured tissue (Kaplanski et al. 2003). In pigs, lymphocytes and macrophages dominate the dioestrous endometrium, but during pro-oestrous and oestrous neutrophils increase signi?cantly in the sub- epithelial connective tissue, preparing the endometrium for a rapid in?ammatory reaction. The in?ltration is positively correlated with oestradiol-17b concentrations and suggests that the oestrogen-dominated uterus has the capacity for rapid initiation of the in?ammatory reaction (Kaeoket et al. 2002). In mares, neutrophil margination in vessels is seen during oestrus, but PMN in?ltration into tissues does not take place in the normal non-in?amed uterus. In cows, PMNs are normally detected in the oestrous endometrium (Ken- ney 1978). The presence of spermatozoa in the uterus induces rapid chemotaxis of PMNs, which are detected in the uterus already 0.5 h after AI in horses and pigs (Katila 1995;