1. serves to receive the sperm in mares
2. transports sperm from site of deposition to uterine tubes for fertilization
3. provides suitable environment for 
   a. implantation of the embryo
   b. nourishment of the embryo & fetus during pregnancy
4. provides mechanical protection of the fetus
5. expels the mature fetus at the end of pregnancy

The diagram to the right shows the parts of the uterus of a sow.    

Other views

Notice the similarities and differences in domestic animals:

1. uterine horns
2. body
3. cervix 

pig
cow
dog
horse
human

gross anatomy: click click here
other domestic species: click here

1. endometrium = tunica mucosa and tunica submucosa
2. myometrium = tunica muscularis
3. perimetrium= tunica serosa   

These are terms specific to the uterus that apply to the typical tunics of a tubular organ. 

Click on the image at the right to view the labeled histological images.

The endometrium  comprises the tunica mucosa and the tunica submucosa of the uterus. 

In the tunica mucosa the lamina epithelialis is usually simple columnar except in the sow and ruminants where it may be pseudostratified columnar. 

The lamina propria consists of loose connective tissue full of neutrophils and lymphocytes.  It blends with the underlying tunica submucosa since there is no lamina muscularis mucosae in the entire female reproductive tract. 

Uterine glands are simple or branched tubular glands located in the lamina propria-tunica submucosa. Some regions of the endometrium in ruminants are void of glands and are highly vascular.  It is in these regions, called caruncles, that contacts between the uterus and the extraembryonic membranes are made.

Click on the image below to view the histological images.

In the sow the stratum vasculare is indistinct and in the cow it may be located in the outer half of the circular muscle layer. 

Click on the image at the right to view the histological images.

In the bitch, queen, and mare the epithelium of the tunica mucosa is simple cuboidal or columnar.  
In ruminants and the sow the epithelium is stratified or pseudostratified.  

Uterine glands may be coiled in ruminants, the sow, and the mare. 

Glands

Uterine glands are simple or branched tubular glands, and may be coiled distally. Distal portions of the glands are in the lamina propria/tunica submucosa. The glands secrete mucus, glycogen, proteins, and lipids. The remainder of the endometrial tissue is loose connective tissue.

Click on the image at the right to view histological images at 2 magnification levels.