A lesser soul than The Green Man may have been tempted to question the relationship Robert Weinberg of the Whitehead Institute for Biomedical Research in Boston had with his mother. The Green Man, on the other hand, is prepared to accept that there is an entirely legitimate reason for growing a female human breast on a mouse.

Of the technique Bob has to say

The key is to transplant two types of human breast cells into the mice, one of which has been blasted with radiation

Those interested in the said mice for research into breast cancer are quite pleased with the outcome. For those looking for some visual stimulation it is back to the drawing board. Unlike human breasts the mice's growths sit flush to the chest.

Read more in Nature.