Anatomy of the mammary gland
The gross anatomy of the mammary gland differs a lot among
different species. The number of glands and teats are not the same for the cow, the sow or the horse. However, the microscopic anatomy is very similar among species.
The development of the mammary gland starts early in the fetal life. Already in the second month of gestation teat formation starts and the development continues up to the sixth month of gestation. When the calf fetus is six months, the udder is almost fully developed with four separate glands and a median ligament, teat and gland cisterns.