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The Mouse Is Not Enough

The invasive nature of embryo retrieval has necessitated the use of a mammalian

The invasive nature of embryo retrieval has necessitated the use of a mammalian species that reproduces rapidly and is inexpensive to house – the mouse.

By Peter Pfeffer and Debra Berg

Fundamental differences in embryonic development mean that research using mice may not be reliably applied to other mammals, and that cattle embryos may be a better model for stem cell studies in humans.

Peter Pfeffer and Debra Berg are Senior Scientists at Agresearch in Hamilton, New Zealand.

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New research has found that mice may not be the best model system for understanding early mammalian embryogenesis. Our study, published in Developmental Cell in February, identifies important differences in the timing of cell fate commitment during the development of mouse and cattle embryos.

It turns out that cattle embryos are a better model for understanding the earliest events in human development. This finding impacts on stem cell biology, explaining why the isolation of embryonic stem cells in humans and other mammals using methods based on mouse biology have failed, and highlights the need to broaden studies to cover more than a single model species.

Embryology is the study of how an animal develops from a single fertilised cell to an incredibly organised and complex multicellular entity. After fertilisation, mammalian embryos undergo several rounds of cell division without growth, forming a solid ball of cells. A cavity develops in the ball leading to a spherical layer of cells enclosing an inner clump or mass of cells attached to one side.

This stage is called the blastocyst, with the inner cell mass giving rise to the entire embryo. The outer layer of cells is called the trophectoderm (TE). This contributes to the placenta, which nourishes the embryo in the uterus. Thus a key event has occurred by the blastocyst stage: cells have decided...

The full text of this article can be purchased from Informit.