Surface transformation of ram spermatozoa in uterine, oviduct and cauda epididymal fluids in vitro

Abstract

Genital tract fluids were collected continuously from conscious ewes through catheters inserted surgically into the uterus and oviducts. Cauda epididymal spermatozoa and fluid were obtained through catheters inserted into the transected vas deferens. The washed spermatozoa were labelled using the surface-specific chloroglycoluril-Na125I procedure. High-resolution electrophoretic analysis of sperm plasma membrane preparations revealed a partial loss of a major surface component (i.e. Mr 97,000) during incubation in uterine and oviduct fluids. This specific loss resulted in a shift in radioactivity distribution toward an Mr 24,000 component which had been previously identified as a sialoglycoprotein. No significant changes in the distribution of radiolabelled surface components were detectable when the spermatozoa were incubated in synthetic medium. Incubation of unlabelled spermatozoa in 125I-labelled uterine fluid showed that adsorption of exogenous fluid components was highly selective; an Mr 16,000 polypeptide was greatly enriched on the sperm surface although it was only a minor component in the incubation fluid. Adsorption of labelled oviduct fluid components was also selective and involved predominantly high molecular weight components (i.e. Mr 140,000, 95,000, 78,000, 53,000). When spermatozoa were incubated in labelled cauda epididymal fluid after exposure to unlabelled uterine and oviduct fluids, several fluid components were incorporated by the plasma membrane, indicating that surface renovation of 'capacitated' spermatozoa may be a more general process rather than a specific event. These results suggest that capacitation of ram spermatozoa involves loss of specific surface proteins as well as selective adsorption of exogenous fluid components and point to a polypeptide in uterine fluid as an active constituent.

Secretions of Ovine Uterus and Oviduct Induce in Vitro Capacitation of Ram Spermatozoa

“…In spite of the adsorption of components from OF by ram spermatozoa during incubation [23], their role in capacitation-acrosome reaction seemed to be limited, since after 1 h incubation in OF we observed a change in the percentage of acrosome-reacted cells but without a further increase ( Figure 2); we did not find a synergism with UF/OF in the induction of the acrosome reaction. Therefore, according to these findings, after 1 h in UF the progress of the acrosome reaction seemed to be time-dependent, up to 3 4 h when this event reached its maximum; the oviductal milieu of estrous ewes did not seem to contribute an essential stimulus to the acrosome reaction.…”

“…According to Voglmayr and Sawyer [23], the in vitro interaction between ovine spermatozoa and female reproductive tract fluids collected at midcycle involves not only a loss of intrinsic proteins from the sperm cell surface, but also a specific adsorption of fluid components by the membranal surface of these cells. Using the occurrence of the acrosome reaction as an assay for the completion of sperm capacitation, the present work was designed to amlyze, by a triple-staining technique [21], the efficiency of UF and OF from the ewe to induct: this biological phenomenon in ram spermatozoa.…”

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

“…It is well-known that the glycoprotein-binding sites on the sperm surface change during sperm transit through the male [4,30] and female [19,31] reproductive tracts. There have been several reports on the Con A, PSA, and WGA lectin-binding characteristics of the surface of canine epididymal and ejaculated sperm [3,7], and the results of this study agree with their findings.…”

“…The results of the present study indicate that a PHA-E lectin-binding protein which is thought to be secreted by the canine prostate is one of the decapacitation factors for canine sperm and that loss of the PHA-E-binding protein on the surface of canine sperm in the oviducts causes induction of sperm capacitation by certain substances, e.g., glycosaminoglycans, in the oviductal fluid of the estrous bitch. It has been found that the glycoproteins on the surface of sperm are removed after exposure to fluids of the female reproductive tract of estrous animals and that their removal induces sperm capacitation [5,6,21,31]. Proteases (enzymes that hydrolyze proteins) in the fluids of the uterus and oviduct have been reported to hydrolyze sperm surface glycoproteins [5,19], and it will be necessary to examine the reproductive tract fluid of estrous bitches for the presence of proteases.…”

Protease-Induced Hyperactivation of Canine Spermatozoa Associated with Disappearance of Lectin-Binding Glycoproteins on their Surface

“…It has been found that some of the glycoproteins on the surface of the sperm of the rabbit [29] and hamster [38] are degraded and disappear as a result of the action of proteases, enzymes that hydrolyze proteins, and that the uterine fluid of the hamster contains proteases [38]. Sperm capacitation in the ewe [40], pig [10] and rabbit [31] is induced by removal of glycoproteins from the surface of the sperm plasma membrane after exposure to fluid in the female reproductive tract, and canine sperm capacitation has been also reported to be related to loss of glycoproteins from the acrosomal regions of sperm [13]. Sperm capacitation is initiated by an influx of Ca 2+ into the sperm cytoplasm [11,12,32,34].…”