If they transplant a uterus into a male body (rat/monkey/elephant/human...) It's still a female uterus.
'Male uterus'. No, I don't think so.
What an utterly cruel and pointless experiment. Rats feel pain, and they can be very clever.
They're not unthinking, unfeeling creatures! That must have been torture to go through.
Not only do they have the surgeries to join them together, to separate them later, C-section births for both rats, surgery to block the female rat from giving birth naturally, and the surgery to implant the uterus into the male rat... The male rats would surely have had pain from the growth of the foetuses, their bodies are not designed to expand to accommodate babies!
The whole thing makes me sick.