Histology of the uterus

Unlike most other vertebrates, mammalian embryos develop within the uterus. This organ is specially adapted to provide a site for embryonic development. Examine this section, which is a cross section of the entire uterus of a small mammal. Use low power first to orient yourself. You should be able to clearly identify the outer muscular layer (myometrium) and the inner lining or endometrium. What type of muscle tissue is the myometrium composed of?

Histology of the pregnant uterus

Examine the section of a pregnant small mammal uterus with fetus. Remember that this is a section, so you will not see an entire fetus. It will probably be difficult to identify the parts of the fetus. Look at the slide first under low power. The light area contains the fetus in its membranes. Surrounding the entire section you should be able to locate the myometrium (smooth muscle layer). Look at the darker area to one side of the fetus. This is mostly endometrium and placenta. The endometrium is thickened during pregnancy.