Sperm Survival and Transport in the Female Reproductive Tract
ABSTRACT Fertilization failure, mostly due to absence of sperm in the oviducts, is a major cause of reproductive inefficiency of farm animals. Sperm may be transported to the oviducts of cattle and sheep within a few minutes after mating or insemination, but these sperm probably fertilize few ova. Slower transport, with establishment of sperm populations in each segment of the reproductive tract, requires a few to several hours. In swine, sperm capable of fertilizing ova reach the oviducts in less than 1 h. Smooth muscle contractions of the reproductive tract, ciliary beats, fluid currents, and flagellar activity of sperm are primary mechanisms of sperm transport. Sperm become hyperactive in the oviducts in association with capacitation. Most sperm in an inseminate drain from the female reproductive tract within a few minutes or hours after insemination; remaining sperm are removed from the tract by slower drainage or phagocytosis. Sperm survival and transport in estrous ewes is reduced drastically by pastures with high estrogen content and by regulating estrus with progestogen or prostaglandin F2 alpha. The cervix is the initial site of inhibition of sperm transport in ewes, and endocrine imbalances probably are the basis of inhibition. Sperm transport problems generally are associated with immobilization and death of sperm in the uterus and anterior segments of the cervix within 2 h after mating. After gilts are inseminated with frozen-thawed semen, relatively few sperm are retained in the reproductive tract, apparently accounting for lowered fertilization rates. Sperm transport has been improved by adding to semen or administering to females such compounds as prostaglandin F2 alpha, oxytocin, estradiol, phenylephrine, or ergonovine. Estradiol, prostaglandin F2 alpha, phenylephrine, and ergonovine administered to rabbits at insemination each increased fertilization rates.
- SourceAvailable from: Pietro S Baruselli
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- "Several experiments have found that 6 hours is the minimum time needed for a viable sperm population capable of fertilization to pass through the oviduct   . Regarding the oocyte, the most desirable period for fertilization appears to be between 6 and 10 hours after ovulation , and the probability of conception decreases when AI is performed near the time of ovulation (less than 6–12 hours before ovulation;  ). "
ABSTRACT: The present study evaluated the effect of the type of norgestomet ear implant (new vs. used) on the ovarian follicular response (experiment 1) and pregnancy per artificial insemination (AI) (P/AI; experiment 2) of beef heifers subjected to an estradiol plus progestin timed artificial insemination (TAI) program. In experiment 1, 57 cyclic beef heifers were randomly assigned to one of two groups according to the type (new or previously used for 9 days) of norgestomet ear (NORG) implant. At the time of NORG implant insertion, the heifers were treated with 2 mg of intramuscular estradiol benzoate. Eight days later, the NORG implants were removed, and the heifers received an intramuscular administration of 150 μg of d-cloprostenol, 300 IU of equine chorionic gonadotropin, and 0.5 mg of estradiol cypionate. The heifers had their ovaries scanned every 12 hours from the time of NORG implant removal to 96 hours after verifying the occurrence and timing of ovulation. No difference (P = 0.89) was observed in the ovulation rates between the two treatments (new = 80.0%; 24/30 vs. used = 81.5%; 22/27). However, the heifers treated with a used NORG implant had (P = 0.04) higher proportion (36.4%; 8/22) of early ovulation (between 36 and 48 hours after NORG implant removal) compared with the heifers treated with a new NORG implant (8.3%; 2/24). In experiment 2, at the beginning of the synchronization protocol, 416 beef heifers were randomly assigned into two groups, as described in the experiment 1. Two days after the NORG implant removal, the heifers were reassigned to be inseminated at 48 or 54 hours after NORG implant removal. There was an interaction (P = 0.03) between the type of NORG implant and the timing of TAI on P/AI. The timing of insemination only had an effect (P = 0.02) on the P/AI when the heifers were treated with a used NORG implant [(TAI 54 hours = 41.9% (44/105) vs. TAI 48 hours = 58.6% (58/99)]. In conclusion, beef heifers synchronized with a used NORG implant plus estradiol exhibited a higher proportion of earlier ovulations, and TAI in these heifers should be performed 48 hours after removal of used NORG implants.Theriogenology 07/2013; 80(6). DOI:10.1016/j.theriogenology.2013.06.008 · 1.85 Impact Factor
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- "In comparison to cilia, as many investigators suggest, the ciliated cells are only normal cellular components of the uterine surface epithelium and there is no clear evidence of their function in endometrium (Masterson et al., 1975; Almeida et al., 1986; Van Cruchten et al., 2002; 2003). To our knowledge, the uterine horns play a major role in sperm transport after insemination, sperm maturation and perhaps sperm capacitation before they travel toward the utero-tubal junction (UTJ) to be stored and await fertilization (Hawk, 1983; Suarez, 2007). After natural or artificial insemination, sperm motility is not important for the rapid transport of sperms through the uterus, but actually the myometrial contractions convey sperms to the UTJ and oviduct (Katila, 2001). "
ABSTRACT: This study was carried out to observe morphological changes of swamp buffalo endometrium at follicular and mid-luteal phases. Uterine horns were collected from female buffaloes at a local abattoir and the selected estrous stages were categorized into the follicular (n = 10) and mid-luteal (n = 10) phases. General histology and histomorphometry were examined under light microscope (LM) whereas a scanning electron microscope (SEM) was used to study surface epithelial changes. The results showed that the height of the endometrial epithelium, the number of superficial endometrial glands and the number of capillaries were significantly greater (p < 0.05) at the follicular phase. By SEM examination, the ciliated and secretory cells with different patterns, i.e. abundant microvilli on the apical part or secretory protrusion in various degrees, distinctly increased at the follicular phase. In the meantime, numerous secretory cells with stubby microvilli were covered throughout the endometrial surface with secretory vesicles on endometrial glandular orifices at the mid-luteal phase in which the ciliated cells were sparsely seen. It was concluded that the swamp buffalo endometrium obviously revealed modifications during the estrous cycle for physiological events, i.e. sperm transport, early embryonic development and implantation.
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- "The LH surge induces ovulation around 24 h later (1) and the fertile life span of the ovine oocyte is 16 to 24 h . In the ewe, spermatozoa take approximately 8 to 10 h to reach the oviduct in sufficient numbers to ensure fertilization   and their lifespan in the oviducts is from 30 to 48 h  . The sum of these observations suggests that in the ewe, 54 to 56 h after the removal of progestagen sponges is the optimum time of insemination coinciding with the time of maximum physiological relaxation of the cervix. "
ABSTRACT: Artificial insemination in sheep has two major limiting factors: the poor quality of frozen-thawed ram semen and the convoluted anatomy of the sheep cervix that does not allow transcervical passage of an inseminating catheter. It has been demonstrated that in the ewe during estrus, there is a degree of cervical relaxation mediated by ovarian and possibly gonadotrohic hormones, and we set out to investigate factors that might enhance cervical relaxation. Five experiments were conducted on ewes of different breeds to determine: 1) the pattern of cervical penetration during the periovulatory period in ewes of several breeds (Welsh Mountain, Île-de-France, Vendéenne, Romanov and Sarda); 2) the effect of the "ram effect" a socio-sexual stimulus, on cervical penetration; and 3) the effects of the intracervical administration of follicle-stimulating hormone (FSH), oxytocin and a prostaglandin E agonist (misoprostol) on the depth of cervical penetration during the periovulatory period. The results showed that during the periovulatory period in all breeds examined, there was increased penetration of the cervical canal (P<0.05) by an inseminating catheter. Cervical penetration increased to a maximum 54 h after the removal of progestagen sponges and then gradually declined. Furthermore, the depth of cervical penetration but not its pattern, was affected (P<0.05) by the breed of ewe. The maximum depth of cervical penetration was lower (P<0.05) in the Vendéenne breed compared to the Île-de-France and Romanov breeds, which did not differ from one another. In the presence of rams, the depth of cervical penetration was increased at 48 and 54 h after removal of sponges (P<0.05) and reduced at 72 h (P<0.05). The local administration of hormones FSH, misoprostol (a PGE agonist) and oxytocin alone and in various combinations did not have any significant effect on the depth of cervical penetration during the periovulatory period. In conclusion, the natural relaxation of the cervix observed in ewes of several breeds occurs at a time during estrus, 54 h after the removal of progestagen sponges, which is the most suitable for artificial insemination. The effect was enhanced by the presence of a ram but not by the local intracervical administration of FSH, misoprostol and oxytocin even though oxytocin and PGE2 are involved in cervical function. The time of maximum cervical penetration in the preovulatory period (54 h) coincides with high LH and estradiol concentrations suggesting they might be responsible for the relaxation of the cervix probably through an oxytocin-PGE mediated pathway.Theriogenology 04/2012; 78(2):376-84. DOI:10.1016/j.theriogenology.2012.02.017 · 1.85 Impact Factor