Follicular function as defined by estradiol-17β production determines in vitro developmental capacity of bovine oocytes derived from preovulatory-sized follicles

Leemput, E.E. van de; Schans, J.M. van der; Vos, P.L.A.M.; Bevers, M.M.; Dieleman, S.J.

doi:10.1016/s0093-691x(98)90653-7

Cited by 7 publications

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“…The treatment did not affect fertilization rates, but a smaller proportion of embryos developed beyond the 16cell stage and the overall percentage of embryos developing to the blastocyst stage was decreased compared to those receiving exogenous pulses of LH (Oussaid et al, 1999). In cattle, blastocyst development was correlated to follicular fluid concentrations of estradiol (Van de Leemput et al, 1998). Follicles with increased aromatase activity were more likely to contain oocytes capable of developing to the blastocyst stage (Driancourt et al, 1998).…”

Section: Timing Of the Lh Surge And Lh Pulse Frequency During Follicumentioning

confidence: 91%

Late embryonic and fetal mortality in the ewe

Dixon¹

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Late embryonic and fetal mortality in the ewe Alison Brown Dixon Timing and factors associated with late embryonic and fetal loss in the ewe were examined with ultrasonography. In study one, pregnancy diagnosis and counts of embryos were conducted on days 25, 45, 65, and/or 85 of gestation and compared to lambs born at term. Preliminary results indicated that more potential offspring were lost during fetal development than during late embryonic development. Approximately 18% of ewes experienced late embryonic and fetal loss and 20% of embryos or fetuses were lost from day 25 to term. Losses of potential offspring were continuous throughout gestation and approximately 3% of embryos present on day 25 were lost during each 20-day interval of pregnancy beyond that point. More ewes lost one, but not all, embryos or fetuses. The pattern of late embryonic and fetal losses during the late breeding season was similar to anestrous or transitional periods. Breeding season and service period did not affect losses during any stage of pregnancy. Late embryonic and fetal mortality was not related to temperature-humidity index. Breed differences affected the proportion of embryos or fetuses lost and concentrations of progesterone, estradiol, and VEGF. A threshold concentration of maternal progesterone was necessary for maintenance of pregnancy and survival of individuals within a litter might be related to a role of vascular endothelial growth factor in placentation. In study two, pregnancy diagnosis was conducted on days 18 and 19 of gestation to determine effects of allantois expansion on late embryonic and fetal mortality. Pregnancy retention from day 18 to term and the number of lambs born per ewe pregnant on day 18 did not differ between ewes with embryos having an expanded or non-expanded allantois. Number of lambs born per ewe lambing tended to be greater in ewes with one non-expanded embryo on day 18. Allantoic expansion on day 18 was not associated with location of corpora lutea. A single embryo was more likely to be lost if it failed to undergo allantoic expansion by day 18 of gestation. iii TABLE OF CONTENTS ABSTRACT………………………………………………………………………………ii TABLE OF CONTENTS………………………………………………………………..iii LIST OF TABLES………………………………………………………………………vi LIST OF FIGURES……………………………………………………………………..ix ACKNOWLEDGMENTS……………………………………………………………….xi REVIEW OF LITERATURE…………………………………………………………….1

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Section: Timing Of the Lh Surge And Lh Pulse Frequency During Follicumentioning

confidence: 91%

Late embryonic and fetal mortality in the ewe

Dixon¹

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“…In cattle, blastocyst development was correlated to follicular fluid concentrations of estradiol (Van de Leemput et al, 1998). Also, follicles with increased aromatase activity were more likely to contain oocytes capable of developing to the blastocyst stage (Driancourt et al, 1998).…”

Section: Intra-ovarian Growth Factorsmentioning

confidence: 99%

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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