Is the Function of the Porcine Sperm Reservoir Restricted to the Ovulatory Period?

Abstract

The uterotubal junction (UTJ) and caudal isthmus are recognized as a functional pre-ovulatory sperm reservoir (SR). Spermatozoa are released from the SR in a complex and concerted action. However, whether this functionality is restricted only to the ovulatory period is still open to debate. Our study was aimed to analyze the presence of spermatozoa within the UTJ (SR), isthmus (ISTH) and ampulla (AMP) after laparoscopic intrauterine insemination (LIUI) either in the peri- (PERI) or post-ovulatory (POST) period or at mid cycle (MID). Each uterine horn of estrus synchronized gilts (n=12) was inseminated with 20 ml sperm (29.5×106 cells/ml). Oviducts were recovered 7 h after LIUI and separated into the UTJ, ISTH and AMP, and sections were flushed with 10 ml PBS+EDTA solution. After centrifugation, the sperm pellet was evaluated by Čeřovský staining. The median sperm numbers in the PERI, POST and MID groups were 578, 171 and 789 in the UTJ; 545, 233 and 713 in the ISTH; and 496, 280 and 926 in the AMP, respectively, and there were differences between the POST and MID groups (P<0.05) but not between the oviductal sections of each group (P>0.05). Compared with the MID group, the percent of intact sperm cells was higher (P<0.01) in the PERI and POST groups (32.8 vs. 66.4 and 76.8%). Also, the percentages of aberrations in the acrosome and tail were higher (P<0.05) in the MID group. Based on this, it can be assumed that the sperm reservoir is active during different phases of the estrus cycle. However, the mid-cycle oviduct environment considerably impairs sperm cell quality.

Identification by proteomics of oviductal sperm-interacting proteins

“…2014). Noteworthy, spermatozoa were stored in higher numbers in the oviduct after insemination at the luteal phase than at the peri-ovoulatory stage but the proportion of damaged and abnormal spermatozoa in the sperm reservoir was also higher (Brussow et al 2014). Taken together, these data suggest that there is a link between the ability of oviductal proteins to interact with sperm cells and the ability of the oviduct to store spermatozoa.…”

Reproductive tract modifications of the boar sperm surface

“…A largely reduced, but apparently fixed, number of sperm reach the tip of the uterine horn, the utero‐tubal junction, and the oviduct within 1 hr post‐insemination (Hawk, ). This efficient rate of sperm transport is made possible by smooth muscle contractions and ciliary beating within the female reproductive tract, resulting in the accumulation of a sperm reservoir at the tip of the uterine horn at the utero‐tubal junction within 1 hr following insemination; only a tiny portion of this reservoir population will enter the oviduct (Bracken, Safranski, Cantley, Lucy, & Lamberson, ; Brüssow, Egerszegi, & Rátky, ; Langendijk et al, ; Mburu, Einarsson, Lundeheim, & Rodriguez‐Martinez, , Mburu, Rodriguez‐Martinez, & Einarsson, ; Sumransap, Tummaruk, & Kunavongkrit, ). Of the 1.5 to 3 billion inseminated sperm, approximately 0.1–0.3 million sperm make up the sperm reservoir at the utero‐tubal junction (Langendijk, Soede, & Kemp, ), and some 2,000 sperm will enter the oviduct; similar quantities of sperm were measured within the sperm reservoir and the oviduct when low‐dose intra‐uterine insemination is performed (Sumransap et al, ; Tummaruk, Sumransap, Techakumphu, & Kunavongkrit, ).…”

Sperm migration, selection, survival, and fertilizing ability in the mammalian oviduct

“… Summarized effects of ovulation time on sperm storage, interactions with luminal epithelial cells, and capacitation in the oviduct. The pre-ovulatory OF [ 4 , 5 , 33 , 93 , 113–115 ] and its proteins [ 123 ] display mostly beneficial effects on sperm physiology and fertilizing ability. Around the time of ovulation, spermatozoa are progressively released from OECs [ 51 , 59 , 114 , 115 ] via the action of chemical compounds, including progesterone [ 37 , 74 , 109 , 116 ] rising in concentrations in the OF at ovulation time and thanks to sperm hyperactivated motility [ 109 ].…”

“…Around the time of ovulation, spermatozoa are progressively released from OECs [ 51 , 59 , 114 , 115 ] via the action of chemical compounds, including progesterone [ 37 , 74 , 109 , 116 ] rising in concentrations in the OF at ovulation time and thanks to sperm hyperactivated motility [ 109 ]. The post-ovulatory OF usually promotes capacitation and acrosome reaction [ 4 , 5 , 33 , 93 , 113–115 ].…”