Influence of Canine Cumulus Oophorus on Homologous Sperm Motility.

Abstract

ABSTRACT. Sperm ejaculated by 8 beagle dogs and the cumuli oophori collected from 3 estrous beagle bitches were co-incubated, and penetration of the sperm into cumuli was observed to investigate the influence of cumuli on homologous sperm.The percentages of hyperactivated sperm and acrosome-reacted sperm were calculated after incubation with homogenized cumuli. The hyaluronic acid content of the incubated cumuli was measured, and hyperactivation and the acrosome reaction of the sperm were evaluated in medium containing hyaluronic acid. The mean percentage of hyperactivated sperm (33.0%) and number (3.0) of sperm that had penetrated a cumulus among sperm incubated for 7 hr were significantly higher than the values for sperm incubated for 0.5 hr (P<0.01). Almost all sperm that had penetrated the cumuli had intact acrosome, as though they were hyperactivated. The percentages of motile sperm (77.3%) and hyperactivated sperm (23.6%) after 2 hr incubation in the medium containing homogenized cumuli were significantly higher than in control medium (P<0.01), but there was no difference between cumulus and control media in the percentages of acrosome-reacted sperm. The hyaluronic acid content of a cumulus increased after 24 hr incubation. After 2 and 4 hr of incubation the percentages of hyperactivated sperm in the medium containing hyaluronic acid were significantly higher than in the control medium (P<0.01). These results suggest that canine hyperactivated sperm with intact acrosome can penetrate homologous cumuli and that the sperm are able to pass through the cumulus because the hyperactivated movement is maintained by hyaluronic acid secreted by the cumulus cells. Therefore, the hyperactivated movement of sperm that have penetrated a cumulus may be maintained by hyaluronic acid, which is also the main component of the cumulus intercellular matrix in many species [1,10,25,28].Sperm penetration into cumuli in many species [24] is made possible by the release of hyaluronidase, an enzyme that hydrolyzes hyaluronic acid, from the sperm head, and the authors have reported that canine sperm also release hyaluronidase [18]. It has been discovered that hamster acrosome-reacted sperm can not penetrate cumuli [5,7] and that the acrosome reaction is induced by homologous zona pellucida (ZP) [27], but there have been no reports on detailed investigation of the relationship between canine sperm and homologous cumuli during fertilization. In the present study, the movement characteristics and morphological changes in canine sperm that had penetrated homologous cumuli were observed. Canine sperm capacitation and the number of ZP-binding sperm after incubation in medium containing homogenized cumuli were examined. The hyaluronic acid content of canine cumuli was measured, and the effect of hyaluronic acid on canine sperm capacitation was investigated. MATERIALS AND METHODS Animals:Eight male beagle dogs, aged 2-5 years, that had normal semen quality were used as sperm donors. Three anestrous beagle bitches, aged 2-4 years, were used...

Effects of Hyaluronic Acid on Ca²⁺ Influx, Lactate Dehydrogenase Activity, and Cyclic AMP Synthesis in Canine Ejaculated Sperm during <i>In Vitro</i> Capacitation

“…The authors have previously reported that maintenance of sperm motility and induction of HA-movement in the dog are caused by the hyaluronic acid that comprises the cumulus intercellular matrix of oocytes [21]. In this study, the effects of hyaluronic acid on canine sperm were comfirmed.…”

“…As a reason for the different result, the hyaluronic acid concentration in the culture medium in this study was lower than in the reports for the other species. The authors have found that the AR of canine sperm is induced by their attachment to the zona pellucida of the oocyte [23], the same as in other species [5,8,10], and not by hyaluronic acid produced by the cumulus cells during penetration of the sperm into the cumulus oophorus [21].…”

“…The cumulus intercellular matrix of oocytes is comprised of hyaluronic acid in many species [3,33,43], including the dog [21], and addition of hyaluronic acid to the culture medium induces capacitation of human [4], bull [37], dog [21], and hamster [45] sperm. The hyaluronic acid produced by the cumulus cells causes HA of sperm that penetrate the cumulus oophorus in many species [3,9,33,43], including the dog [21].…”

Disappearance of the PHA-E Lectin Binding Site on the Surface of Ejaculated Sperm and Sperm Capacitation in the Dog

“…These results suggest that HA-sperm move- ment-inducing substances are present in the oviductal fluid of estrous bitches, the same as in other species [12,15,22], and that loss of PHA-E lectin-binding glycoprotein on the surface of canine sperm is associated with the start of sperm capacitation. The authors [14] previously reported that glycosaminoglycans, a class of mucopolysaccharide, in the oviductal fluid of the estrous bitches induce HA-movement of canine sperm, the same as in the cow [1,8]. Glycosaminoglycans have been shown to cause sperm capacitation as a result of inducing functional changes in sperm cell membrane, absorption of Ca into the sperm and activation of cyclic AMP in the sperm [1,8].…”

Storage and Release of Spermatozoa from the Pre-Uterine Tube Reservoir

“…In the bitch, small numbers of spermatozoa attach to uterine tube epithelium and attachment prolongs the fertile life of spermatozoa [19], [20] by delaying capacitation as observed in other species [21]–[23]. Whilst little is known of the mechanisms for induction of spermatozoal detachment from the uterine tube epithelium, capacitation of dog spermatozoa is induced by oestrous oviductal fluid [24], likely mediated by glycosaminoglycans secreted from uterine tube epithelial cells [25] or possibly by factors associated with cumulus cells [26]. It is however not clear how re-population of the uterine tube reservoir might occur during this prolonged period of time.…”