Aberrant Ovulation–consequences on Fertility and Embryonic Development

Rl, Butcher

doi:10.1093/ansci/34.supplement_1.39

Cited by 4 publications

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“…Ovulation of aged follicles can reduce fertility due to a poor quality oocyte, as observed in rats (Butcher, 1972) and in cattle (Stock and Fortune, 1993;Mihm et al, 1999). Induction of luteolysis at the beginning of progestogen synchronization resulted in ewes ovulating old (7 to 14 days) or young (4 to 5 days) follicles, unlike those that were exposed to high concentrations of progesterone continuously, which ovulated young follicles only (3 to 6 days; Flynn et al, 2000).…”

Section: Approaches To Increasing Ovulation Ratementioning

confidence: 99%

Does peripheral concentration of progesterone affect ovulation and lambing rates in Barbados blackbelly ewes?

Devonish¹

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I would like to thank the members of my committee Drs. Robert Dailey and Marlon Knights for their support and guidance, which allowed me to grow as a scientist. In addition, my sincere appreciation to Dr. Knights for his tremendous support in the acquisition of the knowledge of ultrasonography at West Virginia University, with further training at Greenland Livestock Research Station, Barbados, which allowed me to successfully complete the second replicate of this study. Sincere appreciation is also extended to Dr George Seidel who was very supportive and gave me excellent cooperation in the statistical analysis of the data and Dr Brett Kenney for his adding breadth to my educational experience by exposure novel meat technologies. Special thanks to Ida Holaskova, who was supportive in my overcoming the many challenges in West Virginia that a new student is faced with. Completion of my research studies would not have been possible without the help of my fellow graduate students, particularly, Ms Aimee Wurst and Mr Justin Rhinehart. I wish to express my gratitude to the staff of the Ministry of Agriculture and Rural

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Section: Approaches To Increasing Ovulation Ratementioning

confidence: 99%

Does peripheral concentration of progesterone affect ovulation and lambing rates in Barbados blackbelly ewes?

Devonish¹

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“…A 48-hour delay in ovulation decreased implantation rate, retarded embryonic growth, and increased embryonic death in rats (Butcher and Pope, 1979). Most experimental results from the delayed ovulation of rats indicated that retention of the oocyte in a developing follicle past its normal time of ovulation produced a variety of deleterious effects, which might be manifested at any time from ovulation to the birth of an abnormal offspring (Butcher, 1972). Similarly, Dixon (2007) found that embryos and fetuses were lost throughout pregnancy in the ewe, especially partial losses of multiple pregnancies, which leads one to suggest that similar causes of loss may exist in sheep.…”

Section: Follicular Age and Conceptus Lossmentioning

confidence: 99%

“…Spontaneously prolonged cycles are common in aged animals such as the rat and human (reviewed in Butcher, 1972), and are associated with greater embryonic abnormalities and loss. As previously mentioned, in an attempt to mimic the longer estrous cycle of the aged rat, Butcher and Pope (1979) treated rats with normal 4-day estrous cycles with pentobarbital to delay ovulation for 48 hours.…”

Section: Estrogenmentioning

confidence: 99%

“…All of the detrimental effects of delayed ovulation were reversed by antisera to estrogen, while diethylstilbestrol reinitiated these effects in estrogen antisera-treated rats. Thus, increased embryonic abnormalities and failures of implantation in the aged rat have been clearly shown to be due to extended exposure to high concentrations of estradiol, which altered the follicular and uterine environments of the oocytes (Butcher, 1972;Butcher and Pope, 1979). However, Butcher (1972) suggested that preimplantation stages of rat embryos may show some deviations from normal and still result in apparently normal offspring, because the number of blastocysts classified as normal was sometimes fewer than the number of normal term fetuses (Fugo and Butcher, 1966).…”

Section: Estrogenmentioning

confidence: 99%

“…Thus, increased embryonic abnormalities and failures of implantation in the aged rat have been clearly shown to be due to extended exposure to high concentrations of estradiol, which altered the follicular and uterine environments of the oocytes (Butcher, 1972;Butcher and Pope, 1979). However, Butcher (1972) suggested that preimplantation stages of rat embryos may show some deviations from normal and still result in apparently normal offspring, because the number of blastocysts classified as normal was sometimes fewer than the number of normal term fetuses (Fugo and Butcher, 1966). Page and Butcher (1982) showed that increased estrous cycle length in aged rats was associated with an early increase in intrafollicular and plasma concentrations of estrogen in relation to the time of ovulation.…”

Section: Estrogenmentioning

confidence: 99%

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Effects of ovulation of aged follicles, pregnancy diagnosis by ultrasonography, and treatments during lactation on reproduction in ewes

Wurst¹

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Ewes are polyestrous and litter-bearing seasonal breeders. Although average ovulation rates are sufficient, many ovulations do not result in live offspring and ewes normally breed only once per year. As ovulation rate increases, so does the number of ovulations not represented by live births. When ultrasonographic analysis is limited to ovarian follicles that grow from 3 to 5 mm, follicular waves can be identified in sheep. In most cases, ovulatory follicle(s) develop from the ultimate follicular wave; however, ovulatory follicles can be derived from penultimate or earlier follicular waves. The relationship between lifespan of large follicles and fertility is controversial in sheep. In experiment 1, three approaches to create a model to compare fertility when ovulatory follicles developed from only the ultimate follicular wave or both ultimate and penultimate waves were tested. Ewes were treated on d 10 or 11 with 50 μg of GnRH i.m., the largest follicle(s) (≥ 4 mm) on each ovary were electrocauterized, or ewes were treated with 50 µg estradiol benzoate and 50 mg progesterone or 100 µg estradiol benzoate and 50 mg progesterone in attempts to induce follicular regression or luteinization. Corpora lutea were counted by ultrasound 7 days following estrus in order to verify ovulation of follicles that disappeared post estrus. Pregnancy was determined and embryos were counted 20 to 30 days following estrus. Neither treatment with GnRH nor estradiol and progesterone consistently caused regression or luteinization of ovulatory-sized follicles. Follicular ablation was successful in increasing the proportion of ovulations originating from the ultimate follicular wave in Dorset/Suffolk cross ewes, but did not alter the proportions of ovulations fom different waves in Polypay ewes. Average age of the ovulatory follicle was affected only in Dorset/Suffolk cross ewes. Due to lack of treatment effects, ovulatory follicles were evaluated regardless of treatment for effects on embryonic or fetal losses. Although loss tended to differ among follicular age combinations and wave sources of ovulatory follicles within ewes, older follicles did not have worse outcomes than younger follicles. Lactating ewes have not responded to treatments for the induction of estrus that are effective in dry ewes during the anestrous season. In experiment 2, lactating anestrous ewes 26 to 71 days postpartum were treated with either 25 or 50 mg progesterone/day for five days before ram introduction (RI). Twelve hours after RI, lambs were removed from half of the ewes in each group for 72 hours. Estrous response was recorded and ewes were scanned by transrectal ultrasonography on days 8 and 35 to 45 to determine ovulation rate, and pregnancy rate and number of embryos/fetuses, respectively. Number of lambs born was recorded at lambing. No effect of lamb removal was found for any variable examined. However, the lower dosage of progesterone reduced the mean time to estrus, increased the proportion of ewes ovulating, and decreased an incredible work ethic ...

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Pre‐ovulatory and Post‐ovulatory Overripeness

Butcher

1976

Intl J Gynecology & Obste

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Experimental work using animal models suggests that alterations of the oocyte during either a delay of ovulation or a delay of fertilization could account for a major percentage of human birth defects. The mechanism by which detrimental changes in the oocyte occur during these delays is not known. Hormonal modifications just prior to ovulation could initiate biochemical processes in the oocyte which proceed to an abnormal sequence of events when ovulation or fertilization does not take place at the optimum time. Alternately, the oocyte may be programmed earlier in its growth phase and undergo degenerative changes if ovulation or fertilization does not occur at the programmed times. A better understanding of the mechanisms involved in both pre‐ovulatory and post‐ovulatory overripeness of the oocyte could ultimately lead to a reduction in the incidence of human developmental anomalies.

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Aberrant Ovulation–consequences on Fertility and Embryonic Development

Cited by 4 publications

References 0 publications

Does peripheral concentration of progesterone affect ovulation and lambing rates in Barbados blackbelly ewes?

Does peripheral concentration of progesterone affect ovulation and lambing rates in Barbados blackbelly ewes?

Effects of ovulation of aged follicles, pregnancy diagnosis by ultrasonography, and treatments during lactation on reproduction in ewes

Pre‐ovulatory and Post‐ovulatory Overripeness

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