The Effect of Oestrogen Administered During the Progestational Phase of the Cycle on Transport of Spermatozoa in Ewes

Abstract

Summary. Two split-plot factorial experiments are described, the first with 72 entire cyclic ewes and the second with 80. The pattern of transport of spermatozoa through the reproductive tract was studied, following treatments with progestagen and oestrogen or with oestrogen alone during 2 weeks preceding insemination. A daily dose of 25 \ g=m\ g oestradiol-17\g=b\ administered to ewes for 14 days preceding oestrus had a deleterious effect on the passage of spermatozoa through the cervix into the uterus within the first 2 hr after insemination. The numbers of spermatozoa recoverable from the cranial region of the cervix 2 hr after insemination appeared to be related to the numbers in the oviducts at 24 hr. These numbers were related to fertility data from an earlier experiment using similar treatments. The data for log numbers of spermatozoa recoverable from the cervix formed a near-normal distribution and so were suitable for formal statistical analysis. There was an interaction between progestagen and oestrogen influence before mating on the pattern of sperm transport through the cervix.

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

“…This time-scale is even more rapid than has been previously inferred from reports of significant numbers of spermatozoa being recovered from the cervix at varying times from 15 min to 2 h after insemination (e.g. Mattner 1963a; Quinlivan and Robinson 1969;Lang and Oh 1970;Lightfoot and Salamon 1970;Hawk and Conley 1975;Croker et al 1975). Also, Quinlivan and Robinson (1967) claimed that cervical reservoirs are established within 1 h of insemination.…”

“…Such rapid entry of spermatozoa into the cervix of the oestrous ewe would be advantageous because 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). The numbers of spermatozoa in the cervix 2 h after insemination are correlated with numbers in the oviducts at 22 h (Hawk and Conley 1975) and 24 h (Croker et al 1975) after insemination which emphasizes the importance of the early transport of spermatozoa into the cervix soon after insemination. Croker et al (1975) compared their key data to those of Robinson (1973) and concluded that the patterns of fertility were established within 2 h of insemination.…”

“…The numbers of spermatozoa in the cervix 2 h after insemination are correlated with numbers in the oviducts at 22 h (Hawk and Conley 1975) and 24 h (Croker et al 1975) after insemination which emphasizes the importance of the early transport of spermatozoa into the cervix soon after insemination. Croker et al (1975) compared their key data to those of Robinson (1973) and concluded that the patterns of fertility were established within 2 h of insemination. But there have been no previous studies that have specifically measured fertility in relation to the time of residence of spermatozoa in the vagina.…”

“…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.…”

“…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.…”