Effect of ovulation on sperm transport in the hamster oviduct

Abstract

When hamsters mate shortly after the onset of oestrus (4.5-6 h before the onset of ovulation), spermatozoa are stored in the caudal isthmus of the oviduct until near the time of ovulation. At this time, a few spermatozoa ascend to the ampulla to fertilize the eggs. Superovulation resulted in a significant increase in the number of spermatozoa in the caudal isthmus at 6 h post coitus (p.c.) and in the ampulla and bursal cavity at 12 h p.c. Precocious ovulation resulted in a highly significant reduction in the total number of spermatozoa in the oviduct at 3 and 6 h p.c. This effect was completely overcome by intrauterine artificial insemination, suggesting lack of cervical patency as the block to sperm transport in precociously ovulated animals. Ligation of the ampulla-infundibulum junction in naturally ovulating hamsters resulted in significantly fewer spermatozoa in the caudal isthmus and ampulla at 12 h p.c. Preclusion of ovulation also resulted in fewer spermatozoa in the caudal isthmus and ampulla at 12 h p.c., suggesting that the products of ovulation stimulate sperm transport in the oviduct.

Interaction of Equine Spermatozoa with Oviduct Epithelial Cell Explants is Affected by Estrous Cycle and Anatomic Origin of Explant1

“…In vivo, hamster spermatozoa appear to detach and ascend from the isthmus in approximate temporal relationship to the time of ovulation [35]. The finding that spermatozoal numbers attached to postovulatory explants are not less than those attached to follicular explants suggests that the in vivo control of spermatozoal release is not replicated in this co-culture system.…”

Sperm transport and retention at the fertilization site is orchestrated by a chemical guidance and oviduct movement

“…Thus, the study was focused on the way that spermatozoa were redistributed along the oviduct after ovulation, when the oviduct movement and/or the entry of the ovulation products secreting chemoattractants were suppressed. Earlier in vivo studies, where only the entry of the ovulation products but not oviduct contractions was inhibited, suggested that either chemotaxis (Harper 1973a) or oviduct peristalsis (Ito et al 1991) may transport spermatozoa to the fertilization site. However, these reports could not clearly distinguish which of these sperm transport mechanisms was involved, since oviduct contractions were not controlled in the studies.…”

“…Different types of transport mechanisms have been postulated. One of them may carry spermatozoa by means of oviduct movement (Ito et al 1991), which causes the displacement of the tubal fluid toward the ovarian end of the oviduct (Rodriguez-Martinez et al 1982). The other may orient the movement of capacitated spermatozoa by an increasing gradient of either an attractant molecule (a phenomenon called chemotaxis) or temperature (known as thermotaxis; Eisenbach & Giojalas 2006).…”

“…Under in vivo conditions, it has been observed that spermatozoa were successfully transported from the isthmus to the fertilization site only in the presence of ovulation products (Harper 1973a, Ito et al 1991, which contain the egg complex and consist of cells with the ability to secrete chemoattractants (Sun et al 2005, Guidobaldi et al 2008, Oren-Benaroya et al 2008. However, since peristaltic activity in the oviduct was not controlled, the identification of the sperm transport mechanism was not conclusive.…”

Oestrogen-dependent expression of LH/hCG receptors in pig Fallopian tube and their role in relaxation of the oviduct

“…Hunter (1984) suggested that ovulation can somehow co-ordinate the transport of gametes in the pig oviduct to the ampullar-isthmic junction. However, the transport of spermatozoa from the isthmus to the site of fertilization was synchronized by ovulation in the New World monkey, Cebus apella (Oritz et al, 1995), although the exact nature of the mechanism controlling the passage of gametes and synchronizing the process of fertilization remains unknown (Hunter, 1988;Ito et al, 1991). Stimulation with oestradiol for 24-72 h caused a significant increase in LH/hCG receptors in the oviduct of ovariectomized gilts.…”