Epididymal sperm maturation in the ram : motility, fertilizing ability and embryonic survival after uterine artificial insemination in the ewe

Abstract

Summary. Ram spermatozoa from the distal caput, corpus, and cauda epididymis and ejaculated spermatozoa were artificially inseminated in 170 ewes which had been treated with an ovulatory dose of PMSG 61 ! 4 hrs previously. Results were expressed as the percent of ewes pregnant 18 days after insemination (F = with positive progesterone assay/ Q inseminated) and embryonic survival (ES = ewes lambing/ pregnant on day 18). F =0, 8, 12, 54, 78, 80 and 72 p. 100 respectively after insemination with 20 x 10 6 total spermatozoa/horn from the caput, corpus, I, II and III, proximal cauda, distal cauda, and ejaculate.Development of sperm fertilizing ability parallelled the development of sperm motility. However when ewes were inseminated with high number of motile spermatozoa, ES was 0, 77, 86, 100 and 86 p. 100 with spermatozoa from the corpus I --!-II, the corpus III, the proximal cauda, the distal cauda, and the ejaculate respectively. Thus, the sperm from middle corpus are totally unable to produce viable lambs.In the ram the development of sperm fertilizing ability in the epididymis coincides with the development of progressive motility (Fournier-Delpech et al., 1977) in a maturation process similar to the one described in rodents (reviews of OrgebinCrist et al.,1975OrgebinCrist et al., , 1976Bedford, 1975) or in the pig (Holtz and Smidt, 1976 ;Hunter et al., 1976). However, in the rabbit embryonic mortality is increased after fertilization by immature spermatozoa from the corpus epididymis (Orgebin-Crist, 1969 ; OrgebinCrist and Jahad, 1977). Similarly, litter size in rats is smaller after intra-uterine insemination with epididymal spermatozoa from the corpus than after insemination with spermatozoa from the cauda (Paz et al., 1978 (Colas, 1975 and1979 ;Gordon, 1975 a) After insemination with a constant number of spermatozoa (20 x 10 6 per horn) the pregnancy rate developed constantly which is correlated with the number of progressive motile cells inseminated per horn in the corpus (r = 0.9 in the middle corpus ; r = 0.6 in the distal corpus). However, the plateau is reached at a lower motile sperm concentration and the pregnancy rate is higher when more mature spermatozoa are inseminated ( fig. 2).Progressive motility may be the only essential factor to deliver the fertilizing agent to the oocyte for fertilization. However, development of motility is not definite proof of fertilizing ability for a potential fertile sperm. The pregnancy rate showed that fertilizing ability had not been completely achieved in the middle corpus (60 p. 100 with 20 X 10 6 motile spermatozoa inseminated/horn from the distal corpus versus 90 p. 100 with 8 x 10 6 motile spermatozoa from the distal corpus). Consequently, the acquisition of a mature motility pattern may not be sufficient for fertilization. b) A higher embryonic mortality after insemination with young epididymal spermatozoa has been reported in the rabbit (Orgebin-Crist, 1969) and the pig (Hunter et al., 1976), but was not observed by Overstreet and Bedford (1976) (Fournier...

Seminal plasma aids the survival and cervical transit of epididymal ram spermatozoa

“…Results in the current study are similar to those achieved by Fournier-Delpech et al (1979) who found no significant difference between pregnancy rates of ejaculated and epididymal ram spermatozoa following laparoscopic intrauterine insemination. Similarly, Ehling et al (2006) andÁ lvarez et al (2012) achieved pregnancy rates as high as 87 and 55.8% respectively, when frozen-thawed epididymal ram spermatozoa were inseminated by intrauterine laparoscopic AI.…”

“…Epididymal spermatozoa are fertile when used for ICSI (human: (Silber et al 1995), IVF (Songsasen & Leibo 1998, Stout et al 2012) and even following intrauterine insemination (Fournier-Delpech et al 1979, Hori et al 2005, Ehling et al 2006, Monteiro et al 2011. Moreover, when inseminated in vivo, epididymal spermatozoa have usually achieved pregnancy rates similar to those of ejaculated spermatozoa (Fournier-Delpech et al 1979, Ehling et al 2006, Monteiro et al 2011. Such normal fertility of spermatozoa which have never come into contact with seminal plasma raises the question of whether exposure to seminal plasma from the accessory sex glands is a biological requirement vital for the in vivo function and fertility of spermatozoa or whether this substance is largely superfluous to reproductive success.…”

Fertility of undiluted ram epididymal spermatozoa stored for several days at 4°C

“…Furthermore, the number of lambs born per ewe (fecundity index) was unchanged by the sperm storage period even when the number of motile sperm inseminated was very low. For ram epididymal spermatozoa, embryo loss has previously been observed only for motile spermatozoa for which the fertilizing was not optimal (Fournier-Delpech et al, 1979). Such resistance of sperm during the storage period could be linked to the presence of different sperm populations in the cauda epididymis, as described by Garcia-Macias et al (2006a).…”

“…The spermatozoa become fertile and motile for all species in the last part of the organ (for the ram, see (Fournier-Delpech et al, 1979), and review by (Dacheux and Dacheux, 2014)). Although mature spermatozoa are known to have a short life span, because they have no capacity for synthesis, they can remain viable and fertile in the epididymis for several weeks in vivo (e.g.…”

The origin of a sperm maturation-associated antigen, 54K sialoglycoprotein; an immunohistochemical study with monoclonal antibody MC81 in the mouse.

“…Mammalian spermatozoa undergo functional maturation during transit in the epididymis, modifying biochemical nature of their surfaces (for review, 3,8,10,15,16,[27][28][29]46). The nature of this surface modification is strongly linked to the products which are secreted by the epithelium lining the epididymis (4,5,7,18,20,21,23).…”