Author

Rajesh Sharma
Email

Additional Author(s): H. T. Blair, P. R. Kenyon, T. J. Parkinson

Published on SDB CoRe: Mar 1 2012

Organisms: Vertebrates
Early Embryogenesis: Maternal Determinants
Ecological Developmental Biology: Phenotypic Plasticity
Organism: Sheep
Stage of Development: Embryo

Object Description

This is a lateral view of a day 19 sheep embryo (anterior to the left, dorsal down).  It was collected during a study to examine the effects of the uterine environment on early embryonic development. The gestation period of sheep is around 150 days (humans ~280 days).  Thus, a 19-day sheep embryo is equivalent to about at a 30-day human embryo. The embryonic structures that are visible include the developing brain, pharyngeal arches (P1-P3), heart chambers, liver, somites, mesonephros, and yolk stalk through which the embryo gets nutrients.  

Sheep embryos that develop in a restricted uterine environment (small uterus) are smaller at embryonic day 19 than sheep that develop in a capacious uterine environment (large uterus).  Later at birth, sheep that develop in a restricted uterine environment have a lower birth weight and smaller body dimensions including head width, heart girth, and leg length when compared to controls.  This is an example of how the maternal environment can affect development.

References

Sharma, R.K.2010. The effects of uterine environment upon embryonic, fetal, neonatal and post-natal development and glucose metabolism in sheep. Institute of Veterinary Animal and Biomedical Sciences. Massey University, Palmerston North, p. 235 (PhD Thesis).

Sharma, R.K., Blair, H.T., Jenkinson, C.M.C., Kenyon, P.R., Cockrem, J.F., Parkinson, T.J.Uterine environment as a regulator of birth weight and body dimensions of newborn lambs. J Anim Sci, 2011, PMID: 22079991.

Bryden, M.M., Evans, H.E., Binns, W. Embryology of the sheep. I. Extraembryonic membranes and the development of body form Journal of Morphology, 1972, 138:169-185.

Bryden, M.M., Evans, H.E., Binns, W. Embryology of the sheep. II. The alimentary tract and associated glands, Journal of Morphology, 1972, 138:187-205.

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