Prove in vitro di adesione degli spermatozoi e il loro valore per stimare la fertilità negli animali da reddito

The classic procedure for evaluating the fertility from sires is to determine pregnancy data following artificial insemina- tion. This procedure is time consuming and expensive be- cause of the large number of young bulls entering the bree- ding program. Several studies have been done to find a sim- ple and reliable test for predicting fertility. The perfect test should take into account each and all sperm traits, determi- ning quantity and quality of fertile sperm in a single sperm sample. This review analyze the correlation between in vitro test and in vivo fertility with particular consideration to two tests used in vitro: the sperm zone pellucida binding test and the sperm oviductal cells adhesion test. The first results very useful for the evaluation of sperm destined to in vitro em- bryo production, but fails in predicting male fertility when mating or artificial insemination practices are used. The di- rect encounter between sperm and oocyte, without consider the natural physiological barriers that sperm must overpass into the female tract could be the main reason of failing. On the other hand, the sperm adhesion to the oviduct seems to be an in vivo requisite to fertilization. The oviduct is consi- dered to select the non capacitated - live - non damaged pla- sma membrane sperm that are considered as the fertilizing population. In this way the sperm - oviduct binding test has been developed. Several factors that could influence the test results such as the origin of the tissue used and the cell ex- plant size, are discussed. The available information about the use of this test is still short, however the test has a great po- tential for the sires sub-fertility evaluation, even though its accuracy should be limited to certain type of sperm samples.