Sexual reproduction by union of male and female gamets.
Humans are mammals
urethra
All mammals expend a significant amount of energy producing milk for their offspring. This is an evolutionary feature unique to mammals and it confers a significant benefit to the offspring - the milk is complete nutrition for the offspring, which gives the offspring better odds of surviving to reproductive age itself.
Polar bears are mammals. The reproductive systems of all mammals contain gonads. Gonads are the glands that produce reproductive cells. In males the gonads are called testes and produce sperm and in females they are called ovaries and produce eggs.
Scientists can tell Megatheriums were mammals by examining their skeletal features, which show characteristics common to mammals such as specialized teeth, a jaw structure adapted for chewing, and a reproductive system unique to mammals. Additionally, the presence of hair or fur impressions in some preserved specimens further supports the idea that Megatheriums were mammals.
It would depend on which animal you are referring to, mammals have much the same reproductive system. Birds, fish and insects which are also animals do not.
Horses are mammals and have the same reproductive anatomy as other mammals (including humans). City boy, aren't you?
No, reptiles do not have menstrual cycles or periods like mammals do. Instead, they have reproductive cycles that are different from those of mammals.
What are the common ailments of the reproductive system?
The common ancestor of mammals and birds was a reptile.
Ribs
The lower end of female reproductive tract in pigs is not very different from humans. The reproductive system is conserved across all mammals.