gerbil introduction and sexing

Question
We recently purchased three gerbils which the shop said that they thought were females but no guarantees.  Sadly two of them quickly died and we were left with one lone gerbil whose personality changed almost overnight - became jumpy and introverted.  We knew she was probably lonely and so we have spent the past week introducing her to another female through the split tank method.  This has gone well - probably because they are both young - and they are now happily settled in the big tank together.  I have now begun to worry whether the original gerbil is infact a female after all.  We have scrutinised her over and over again but we are just not experts.  The openings underneath appear to be close together and we canot see any extra bits - bulges etc - would these be obvious on a male gerbil of around 3 months old?  Please help me get over my paranoia!

Answer
Hello,

It sounds as though they are both female bu obviously i can not say 100% as i am not able to look myself. If in doubt why no pop them in a carrier and take them back to the pet store and ask them to re-sex them. This way you will feel a bit more relaxed about it. If they do happen to be mixed sex and have babies it is ok. The pet shop should take these off your hands as it would be their mistake. Not only this but the female/male babies could then be companions for the mother and father, so either way you have a solution!! Don't panic though, your judgement is probably right but do go to the pet shop and get the reassurance!!

Charlie