Adaptations to reduction of endometrial surface available for placental development in sheep

Caton, Donald; Bazer, Fuller W.; Kalra, Pushpa S.; Moffatt, R. J.

doi:10.1530/jrf.0.0720357

Cited by 15 publications

(10 citation statements)

References 18 publications

(18 reference statements)

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“…1 9 9 8 ) . Furthermore, in sheep, experimental reduction of the endometrial surface of the placenta stimulates compensatory changes, such as hypertrophy of the placentomes and marked increases in placental blood flow (Caton et al 1984). In the mare, on the other hand, age-related degeneration of the endometrial vasculature and higher vascular resistance have been reported in mares with endometrosis (Stolla and Bollwein 1997).…”

Section: Discussionmentioning

confidence: 99%

The effects of maternal age and parity on placental and fetal development in the mare

Wilsher

Allen

2003

Equine Veterinary Journal

139

111

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Reasons for performing study: The normality of equine placentation is essential for fetal health and development. Substantial information exists on the gross morphological status of the placenta but few studies have addressed the problem of degenerative lesions that interfere with placental morphology and placental efficiency. Hypothesis: Degenerative changes in the endometrium with increasing age and parity are reflected in the morphology and density of the placental microcotyledons. Objective: To assess placental efficiency on the basis of foal b i rthweight as a function of total microscopic area of fetomaternal contact. Methods: Stereology was used to examine the placentae of 84Thoroughbred mares grouped on the basis of age and parity. Placental efficiency, assessed by expressing foal birthweight as a function of total microscopic area of fetomaternal contact, was also determined. Results: Mare age and parity influenced the development of the microcotyledons and microcotyledon surface density (S v ) was lowest in aged multiparous mares, presumably due to degenerative changes in their endometrium. However, primiparous mares also showed significantly lower S v values than young multiparous mares, despite the virginal endometrium of the former group. This apparent 'priming' effect of a first pregnancy on microcotyledonary S v was illustrated furt h e r by 11 maiden mares followed in 2 successive pregnancies. They all showed significant increases in S v values in their second parity, with equivalent improvements in foal birthweight. Conclusions: Foal birthweight is a reflection of the balance between fetomaternal contact and placental eff i c i e n c y. I n c reases in fetomaternal contact are correlated to reductions in placental efficiency, which may reflect the ability of the placenta to modify its exchange capabilities. Potential relevance: Further work is needed to elucidate how such changes in microcotyledon morphology and efficiency are brought about.

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Section: Discussionmentioning

confidence: 99%

The effects of maternal age and parity on placental and fetal development in the mare

Wilsher

Allen

2003

Equine Veterinary Journal

139

111

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“…Additionally, factors that affect fetal growth, such as maternal and fetal genotype, increased numbers of fetuses, maternal nutrient deprivation, environmental stress, or high altitude, typically have similar effects on placental size (see Reynolds et al 2005, for review). Fetal and placental weights also are reduced when the available uterine surface area is reduced experimentally (Alexander 1964;Knight et al 1977;Caton et al 1984).…”

Section: Placental Microvascular Growth and Functionmentioning

confidence: 99%

Functional Significance of Developmental Changes in Placental Microvascular Architecture

et al. 2005

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“…In those ewes, when the number of lambs born is less than the original number of fetuses carried by the ewe, the 'survivor' fetuses may be compromised by having fewer cotyledons compared with lambs born in a similar litter size in which fewer fetuses were present from the beginning. However, this may not be the case because it has been shown that restricting the number of fetal placentomes by uterine ligation has no effect on fetal weight or fetal crown-rump length (Caton et al 1984;Ott et al 1997).…”

Section: Discussionmentioning

confidence: 99%

Carrying the FecB (Booroola) mutation is associated with lower birth weight and slower post-weaning growth rate for lambs, as well as a lighter mature bodyweight for ewes

Gootwine

Rozov

Bor

et al. 2006

Reprod. Fertil. Dev.

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The present study was conducted in an Assaf flock in which the FecB (Booroola) mutation was segregated to determine whether the FecB mutation affects birthweight and the pre- and post-weaning growth rate of ewe lambs, as well as the mature bodyweight of ewes. Significant differences (P = 0.01) in birthweight (mean +/- s.e.m.) were found between BB ewe lambs (4.03 +/- 0.08 kg) and B+ and ++ ewe lambs (4.16 +/- 0.04 and 4.32 +/- 0.07 kg, respectively), which themselves did not differ significantly (P > 0.05). An FecB-associated maternal effect on the birthweight of ewe lambs was also detected, with the birthweight of lambs born to BB mothers (3.93 +/- 0.08 kg) being significantly (P < 0.0001) different from the birthweight of lambs born to B+ and ++ mothers (4.26 +/- 0.04 and 4.33 +/- 0.07 kg, respectively), which did not differ significantly. The genotypes of the lambs did not affect their preweaning growth rate. However, the post-weaning growth rate of ewe BB lambs (274 +/- 5 g day(-1)) was significantly (P = 0.05) different from the similar (P > 0.05) post-weaning growth rates of B+ and ++ lambs (284 +/- 3 and 290 +/- 4 g day(-1), respectively). The genotype at the FecB locus also affected the mature bodyweight of ewes, with that of BB ewes (67.3 +/- 1.4 kg) being significantly (P < 0.001) different from the similar mature bodyweight of B+ and ++ ewes (70.8 +/- 1.1 and 70.1 +/- 1.7 kg, respectively).

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Adaptations to reduction of endometrial surface available for placental development in sheep

Cited by 15 publications

References 18 publications

The effects of maternal age and parity on placental and fetal development in the mare

The effects of maternal age and parity on placental and fetal development in the mare

Functional Significance of Developmental Changes in Placental Microvascular Architecture

Carrying the FecB (Booroola) mutation is associated with lower birth weight and slower post-weaning growth rate for lambs, as well as a lighter mature bodyweight for ewes

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