Mammal, uterus (LM, Medium)

Structure List Mucosa Tubular glands Circular muscle layer Longitudinal muscle layer Low Magnification View

THE UTERUS. The uterus has a structure like that seen in the uterine tube except that the layers are much thicker. In addition, these layers have been given special names. The mucosa, muscularis, and serosa are called endometrium, myometrium and perimetrium, respectively. The ENDOMETRIUM consists of a simple columnar epithelium and a wide lamina propria which contains the uterine glands. The uterine glands are simple tubular glands which are lined with columnar epithelium like the uterus. The glands open directly into the uterine cavity and extend to the muscularis. Some of the epithelial cells have cilia, which beat toward the surface in the glands and toward the vagina in the lumen. The MUSCULATURE of the uterus is composed of smooth muscle interspersed with considerable connective tissue. The muscle layers are not easily discernible; in general, the cells in the central layer are circularly arranged and those on either side are longitudinal. The middle region contains many blood vessels in the stratum vasculare. The uterus is greatly distended during pregnancy which is accomplished by the addition of new cells. Since many of these cells remain after parturition, the uterus does not return to its nulliparous size. There is also an increase in elastic tissue and blood vessels, many of which remain.