PDF《Duration》

Kaeoket et al. 2003c). PMN numbers peak between

4 and

8 h in the mare (Katila 1995) and 3C6 h in pigs (Rodriguez-Martinez et al. 2010). The numbers remain elevated for

24 h, but by 40C48 h only a few PMNs are found in mares and gilts (Katila 1995;

Kaeoket et al. 2003c). Howe and Black reported that PMNs peak at around 8C16 h in cattle, whereas more recently, Alghamdi et al. proposed that PMNs peak already in ?2 h (Howe and Black 1963;

Alghamdi et al. 2009). In all these species, the onset of PMN chemotaxis is rapid and the duration of PMN in?ltration relatively short. This ensures e?ective removal of sperm and bacteria and subsequent return of the endometrium to a normal state, prepared to receive the embryo. Although infusion of any kind of semen or ?uid into the uterus of mares or gilts causes in?ammation (Kotilainen et al. 1994;

Schuberth et al. 2008;

Taylor et al. 2009a), spermatozoa initiate the strongest PMN response (Kotilainen et al. 1994;

Rozeboom et al. 1998, 1999). In pigs, a SP protein belonging to the spermad- hesin family, porcine SP (PSP-I)?PSP-II heterodimer, plays a major role in triggering PMN recruitment (Rodriguez-Martinez et al. 2010). Spermatozoa are not inherently chemotactic, but they activate a complement cascade in uterine secretions. This was demonstrated in horses and pigs (Troedsson et al. 2005). The complement cascade mediates a series of biological reactions, including vascular permeability, chemotaxis and opsonization for phagocytosis. Activa- tion of the complement (C) cascade cleaves factor C5 into C5a and C5b, of which C5a mediates chemotaxis of PMN (Tizard 1996). Activated PMNs bind to spermatozoa and phagocy- tize spermatozoa. Sperm-neutrophil binding is mediated by direct cell membrane attachment or by NET (neu- trophil extracellular trap) entanglement. The direct cell attachment involves either a direct receptor-ligand mechanism or opsonization (complement or antibodies) (Alghamdi et al. 2009). The binding of viable sperm to PMNs is most lik........