Current Knowledge on the Transport and Fate of Spermatozoa in the Reproductive Tract of the Bitch

Abstract

ContentsCanine sperm transport, distribution, storage and detachment is a complex, dynamic and highly regulated process. Transport of sperm within the bitch's reproductive tract is rapid and is influenced by the method of semen deposition (natural mating or artificial insemination) and by the timing of breeding in relation to the day of ovulation. The fertile lifespan of spermatozoa in the reproductive tract of the bitch is considerably longer than in most other domestic species, and the main sperm reservoirs appear to be the uterine crypts and the distal part of the uterotubal junction, where spermatozoa attach by their heads to uterine epithelium. While several in vitro studies demonstrated prolonged motility and viability of canine spermatozoa after coincubation with uterine tube explants, spermatozoal storage has not been documented in the canine uterine tube isthmus or ampulla in vivo. Several factors, including exposure to progesterone, solubilized zona pellucida proteins and post-ovulation uterine tube fluid, appear to trigger membrane events resulting in capacitationlike changes with subsequent motility pattern changes (transitional and hyperactivated) that are associated with sperm detachment. After mating or insemination, a normal lowmagnitude post-mating uterine inflammatory response occurs, evidenced by an influx of polymorphonuclear neutrophils (PMNs), increased uterine contractions and an increased uterine artery blood flow. Recently, it was also shown that normal dogs with cystic endometrial hyperplasia develop a more significant endometritis, show fewer mating-induced uterine contractions, a decreased ability of spermatozoa to bind to uterine explants in vitro and a slower uterine clearance after mating.

An update of the regulatory factors of sperm migration from the uterus into the oviduct by genetically manipulated mice

“…The most major obstacle for sperm that enters the uterus, however, is a passage through the uterotubal junction (UTJ). The UTJ is the connection between the uterus and the oviduct and is well characterized as the distal portion of the oviduct (Rijsselaere, England, Freeman, Maes, & Van Soom, 2014). Although the structure of the UTJ varies substantially among different mammalian species, this passageway is usually narrow (Fujihara, Miyata, et al, 2018;Suarez & Pacey, 2006).…”

Concentrations of minerals in the canine prostatic fluid

“…As in other species, various functions of the prostatic fluid have been postulated in the dog and described in the literature, for example, transportation (Rijsselaere, England, Freeman, Maes, & Van Soom, ) and nutrition of spermatozoa (Mann & Lutwak‐Mann, ). Recently, the interest in seminal plasma research and its components was re‐raised and a number of proteins, as for example arginine esterase and lactotransferrin precursor, had been identified by proteomics in canine seminal plasma (Aquino‐Cortez, Pinheiro, Lima, et al, ).…”

The Dog: Nonconformist, Not Only in Maternal Recognition Signaling

“…Moreover, the uterus, and not the oviductal ampulla or isthmus, seems to be the major sperm reservoir in the bitch (Bischoff 1845 ;Pacey et al 2000 ;Rijsselaere et al 2014 ). The "fertilization window," i.e., the time period when a bitch can be successfully mated, is relatively long and variable.…”