sexing

Hi! Just brought home three new rats, about a month old according to where we got them from, and supposedly all male. However, one I am not so sure. The others have already developed testes but one hasn’t. I don’t think the spacing between urethra and anus is wide enough to indicate a female...

we bought three rats as males, all the same age, but two have visible testes and one doesn't. he doesn't look quiet female though, either, as according to the guides on sexing i've been looking at. please share your thoughts!! if he is female we have to return him to the seller ASAP to prevent...