50.1 MB (50.0 MB compressed)
4854 x 3604 pixels
41.1 x 30.5 cm ⏐ 16.2 x 12.0 in (300dpi)
MARTIN OEGGERLI / SCIENCE PHOTO LIBRARY MARTIN OEGGERLI / SCIENCE PHOTO LIBRARY
Pronuclear egg cells. Polarised light micrograph of eggs (female reproductive cells) from a mouse (Mus musculus). Each of these eggs has a pronucleus, where sperm has entered the egg (ovum) but the sperm's nucleus has not yet fused with the egg's nucleus to form the zygote (the single-celled embryo at the beginning of embryo development). The genetic material from these cells will be removed and replaced with genetic material from a cell of another animal species, a procedure known as transgenics.
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