Numbers of Spermatozoa in the Genital Tract After Artificial Insemination of Progestagen-Treated Ewes

Abstract

Summary. An experiment is described in which spermatozoa were recovered from genital tracts of ewes either at the first oestrus following progestagen synchronization or at a normal oestrus.Recoveries 1, 12, 24, 36 and 48 hr after the insemination of 500\m=x\106 spermatozoa show that synchronization with intravaginal sponges impregnated with the synthetic progestagen 17\g=a\-acetoxy-9\g=a\-fl uoro-11\g=b\\x=req-\ hydroxypregn-4-ene-3,20-dione (Cronolone, Searle) alters the numbers and distribution of spermatozoa throughout the female genital tract at the first oestrus after treatment.One hour after insemination the total numbers of spermatozoa recovered, and their distribution between the various regions of the tract, differed little between progestagen-treated and untreated ewes. Thereafter the numbers recovered from treated ewes were significantly fewer than from untreated, and their distribution differed. Significant differences appeared in the vagina at 12 hr and in the cervix and uterus at 24 hr and thereafter this difference was maintained. The pattern in the Fallopian tubes followed that of the uterus. At 24 hr the mean numbers of tubal spermatozoa recovered were: synchronized\p=m-\900; non-synchronized\p=m-\8200(P< 0\m=.\001).Both transport and survival of spermatozoa may be deleteriously affected in the reproductive tract of the progestagen-treated ewe.

Time Required for Spermatozoa to Remain in the Vagina of the Ewe to Ensure Conception

“…Nevertheless, Quinlivan and Robinson (1969) found a significant correlation between the number of spermatozoa in the vagina and in the cervix 1 h after insemination and suggested that the vagina was important in establishing a large cervical population. Therefore, the magnitude and speed of the losses of spermatozoa from the vagina in the first few hours after mating are likely to affect the number of spermatozoa reaching the cervix and hence the chances of conception.…”

“…If this is the case, the effectiveness of the transport of spermatozoa through the reproductive tract of the ewe in the first 8 h after insemination will be vital to the chances of conception. The cervix plays an important role in this as it is the site of formation of primary reservoirs of spermatozoa (Quinlan et al 1933;Dauzier and Wintenberger 1952;Mattner 1963aMattner , 1963bMattner , 1966Mattner , 1968Quinlivan and Robinson 1969) and within the cervix spermatozoa are well protected (Robinson 1973) and retain their motility longer than in other parts of the tract (Quinlan et al 1933). It has been suggested that fertility can be predicted by the number of spermatozoa in the cranial third of the cervix 2 h after insemination (Croker et al 1975).…”

“…Hence the chances of conception will be dependent on the speed of establishment of an adequate population of spermatozoa in the cervix. The speed that such a population is established in the ewe is unknown although it is likely to be within a few hours of mating because large numbers of spermatozoa have been reported in the cervix from 15 min to 2 h after mating or insemination (Mattner 1963a; Quinlivan and Robinson 1969;Lang and Oh 1970;Lightfoot and Salamon 1970;Hawk and Conley 1975;Croker et al 1975). During the period required to establish an adequate cervical population of spermatozoa the vagina must act as a reservoir for spermatozoa.…”

“…During the period required to establish an adequate cervical population of spermatozoa the vagina must act as a reservoir for spermatozoa. The importance of the vagina as such a reservoir has not been defined (Quinlivan and Robinson 1969) but, because spermatozoa pass rapidly into the cervix after insemination Robinson (1975) considered that the vaginal environment was relatively unimportant.…”

“…Most of the spermatozoa inseminated into the vagina of a ewe are lost by drainage to the exterior (Conley and Hawk 1969;Quinlivan and Robinson 1969;Hawk and Conley 1971;Tilbrook and Pearce 1986) and we have described the pattern of this loss (Tilbrook and Pearce 1986). The initial loss after insemination was not rapid, with 82% of the inseminate remaining in the vagina after 3 h. Spermatozoa were lost rapidly from the vagina between 3 and 9 h after insemination and withdrawal of the ram's penis after intromission contributed to this loss depending on the volume of semen in the vagina.…”