Reproductive System

        All mammals are considered to be viviparous, meaning that the young are

carried within the mother's body during development, and then after the live birth,

the young are released to live on their own. Mammals produce sexually with the

male sperm being introduced into the female vagina by the penis. The reproductive

system of the male mammal will have a prostate gland, what is called a

bulbourethral gland, and seminal vesticles inside of his body. Plus, two-sperm-

producing testicles which usually remain outside of the body. Female mammals

have two egg-producing ovaries, fallopian tubes that transport egggs, and a uterus

where the fertilized egg grows and matures.

        There are some female primates that menstruate and undergo menopause in the

same way that women do.  Specifically, the way in which pregnancy is maintained

by following fertilization and implantation fo the embryo into the uterus, is shared

by all the different primates.  During the first trimester, it is responsible for

synthesising progesterone, which is a hormone without which a pregnancy would

not progress. So, the corpus luteum has to be  switched on at the right time and just

as importantly, switched off as well. This step is key to understanding how the body

maintains a pregnancy. 

        Most of the reproductive systems of mammals are very similar. Although,

obviously, there are notable differences between the normal mammal and humans.

For example, most mammalian males, like Chimpanzees, have a penis which is

stored internally until erect, and most have a penis bone, also known as the

baculum. Also, males of most species do not stay continually sexually fertile as

humans do. Like humans, most mammals have descended testicles found within a

scrotum, while others have descended testicles that rest on the ventral body wall.

         Marsupials are unique in that the female has two vaginae, both of which open

externally through on orifice, but lead to different compartments within the uterus.

Also, the males usually have a two-pronged penis which corresponds to the females'

two vaginae. Marsupials normally develop their offspring in an external pouch that

has teats to which newborn young attach themselves for post uterine development.