A. Schematics for the generation of rats with mouse gametes. Mouse spermatids isolated from the rat testis are injected into unfertilized mouse eggs to produce viable mice. B. Section of rat ...

The testes of the mouse/rat hybrids seen up close using Immunofluorescence staining. The green and red spots mark the presence of sperm-associated proteins that otherwise would have been missing ...

The previous finding that testes size was independent of body mass held up well, ... But for whatever reason, for the rats, mice and squirrels that live among us, size is a big deal.

Rie Natsume and her collaborators have recently developed an innovative and cost-effective method for generating rats that inherit traits from embryonic stem (ES) cells. Unlike mouse ES cells, rat ES ...