Oviductal epithelial cells selected boar sperm according to their functional characteristics

Abstract

The interaction of oviductal epithelial cells (OECs) with the spermatozoa has beneficial effects on the sperm functions. The aim of this study is to evaluate the in vitro fertilizing capacity of incubating spermatozoa previously selected by density gradient in OEC and determinate some sperm characteristics that could explain the results obtained. In this study, we assessed in vitro fertilization (IVF), tyrosine phosphorylation, phosphatidylserine translocation, nuclear DNA fragmentation, and chromatin decondensation. Three experimental sperm groups, previously selected by Percoll gradient, were established according to the origin of the sperm used for IVF: (i) W30 group: spermatozoa were incubated with oocytes in the absence of OEC; (ii) NB group: after sperm incubation in OEC, the unbound spermatozoa were incubated with oocytes, in the absence of OEC; and (iii) B group: after sperm incubation with OEC, the bound spermatozoa were incubated with oocytes in the OEC plates. The results showed that sperm from the NB group led to a lower IVF yield, accompanied by low penetration rates (NB: 19.6%, B: 94.9%, and W30: 62.9%; P < 0.001) and problems of nuclear decondensation. Moreover, higher levels of tyrosine phosphorylation were observed in the NB group compared with the W30 and B groups (NB: 58.7%, B: 2.5%, and W30: 4.5%; P < 0.01). A similar trend was observed in phosphatidylserine translocation (NB: 93.7%, B: 5.7%, and W30: 44.2%; P < 0.01). These results demonstrate that the OEC exerts a rigorous degree of sperm selection, even within an already highly selected population of spermatozoa, and can capture the best functional spermatozoa for fertilization.

Sperm function in vitro and fertility after antibiotic-free, hypothermic storage of liquid preserved boar semen

“…The binding of spermatozoa to oviductal cells forms a reservoir 43 which is mediated by carbohydrates on the oviductal cell apical membranes and lectin-like molecules on the sperm surface 44,45 . Several studies have shown that oviductal epithelial cells select boar spermatozoa according to their functional membrane-mediated characteristics 36,46,47 . The slightly reduced binding capacity of spermatozoa stored at 5° observed in the present study may be attributed to chilling-induced membrane lipid alterations.…”

Graphene Oxide increases mammalian spermatozoa fertilizing ability by extracting cholesterol from their membranes and promoting capacitation

“…Finally, as we know, sperm membrane is the interaction site of male gametes with the surrounding environment and, consequently, it is involved in the information exchange that leads the spermatozoa to the acquisition of full fertilizing ability. Several reports agree in describing two different pools of male gametes within the oviduct: one group of spermatozoa present within the lumen, not bound to the epithelial cells and characterized by poor viability and unable to fertilize, and another group, encompassing spermatozoa attached to the OECs with potentially capacitated cells that will be able to fertilize the oocyte 58 . To date, the specific molecular mechanisms involved in such interaction are not completely understood, but it has been supposed that the membrane glycocalyx could be involved 40 .…”

Sperm selection by the oviduct: perspectives for male fertility and assisted reproductive technologies

“…A plethora of in vitro studies supports this narrative (see Table 2). Overall, they show that OECs preferentially bind uncapacitated sperm [64,93,100,101] with higher DNA integrity [102,103]. Some of the differences observed between bound and free-swimming sperm were detected only after 3 minute of incubation [93].…”

“…There are several studies showing that sperm incubation with OECs can improve IVF success, perhaps due to effects on sperm adhesion to the OECs [64][65][66]. Sperm heads bind specific oligosaccharides containing glycan motifs that are part of the OECs glycocalyx (see reviews [67,68]).…”