Pathology Thread

I. Gross Anatomy and Histology

Objectives:

After completing this section you will be able to:

• list and identify the various parts of the uterine corpus
• describe the gross anatomy and histology of the corpus

1. Anatomy

The body of the uterus is the upper, broad, piriform part of the uterus. It is a hollow, thick-walled, muscular organ with a flat anterior surface and a convex posterior surface. The component parts are the:

• Fundus, the dome-shaped upper part of the corpus above and between the entrances of the fallopian tubes.
• Cornu, the region of the body on each side, where the fallopian tube enters.
• Body, the part that lies below the entrances of the fallopian tubes.
• Isthmus, the narrow zone of constriction on the external surface just above the cervix and serves as the junction between corpus and cervix. It corresponds in the interior to the lower uterine segment, which ends at the internal cervical os.
• Endometrial cavity, the lumen of the body which, in coronal section, is triangular.

Question: What is the clinical importance of the lower uterine segment?

2. Histology

The endometrial cavity is lined by the endometrium, which is made up of epithelium and stroma. The surface epithelium invaginates to form numerous tubular endometrial glands, which extend down into the specialized endometrial stroma. The endometrium consists of a thick superficial layer made up of the outer two-thirds and called the functional layer (zona functionalis) and a thin, deep, basal layer (zona basalis) formed by the inner one-third. The functional layer undergoes cyclic changes in response to sex hormones and is shed with each menstruation. The basal layer is the germinative portion and, with e ach cycle, regenerates a new functional layer.

Underlying the endometrium is the myometrium, the thick, smooth muscle layer of the corpus. Externally is the serosa, which is the peritoneal covering of the uterus..

Endometrium with underlying myometrium (lower third).