Reply to comment by [deleted] in TIL, the placenta that forms with a fetus isn't created by the mother. It grows from the fertilized egg and some fetuses actually develop outside the uterus attached to the intestines in the body cavity. by darw1nf1sh

Reply to comment by _Dnikeb in TIL, the placenta that forms with a fetus isn't created by the mother. It grows from the fertilized egg and some fetuses actually develop outside the uterus attached to the intestines in the body cavity. by darw1nf1sh

Reply to comment by goltz20707 in TIL: Sperms were thought to move by wiggling their tails side-to-side, like eels, for 350 years. But research shows that they roll as they move forward like a spinning top. by vect77