Special Histology and Embryology: Practical Course - V. K. Naphpanyuk 2001

Reproductive System
Female Reproductive System
Uterus

The uterus is a muscular, pear-shaped organ designed for the INTRAUTERINE DEVELOPMENT OF the fetus.

The uterine wall consists of three layers: the mucosal layer (endometrium), the muscular layer (myometrium), and the serosal layer (perimetrium).

The endometrium is divided into two layers: the basal layer and the functional layer. It is lined with a simple columnar epithelium composed of Two Types of Cells—ciliated and secretory. The epithelial layer extends into the lamina propria, forming tubular invaginations known as uterine glands, or crypts.

The lamina propria of the mucous membrane consists of loose Fibrous Connective Tissue rich in cellular elements, including decidual cells that develop during the secretory phase of the Menstrual cycle.

The myometrium is composed of three layers of smooth Muscle cells: 1) the inner submucosal layer (stratum submucosum); 2) the middle vascular layer (stratum vasculosum), which is rich in Blood Vessels and features smooth myocytes running in an oblique-longitudinal direction; and 3) the outer supravascular layer (stratum supravasculosum), which also has an oblique-longitudinal orientation of muscle cells, intersecting with the submucosal layer.

Between the bundles of muscle cells lie connective tissue partitions rich in elastic fibers.

The perimetrium consists of loose fibrous connective tissue covered by mesothelium. It covers most of the uterine surface, except for the anterior and lateral surfaces of the supravaginal portion of the uterine cervix.

A large accumulation of adipose tissue, known as the parametrium, surrounds the cervix, particularly laterally and anteriorly.

The mucous membrane of the uterine cervix, like the Vagina, is covered with stratified squamous epithelium. The cervical canal is lined with mucus-secreting columnar epithelium. However, the largest amount of secretion is produced by numerous relatively large, branched glands located within the stroma of the mucosal folds. The muscular coat of the cervix features a robust circular layer of smooth muscle cells that forms the so-called uterine sphincter; its contraction expels mucus from the cervical glands. Relaxation of this muscular ring creates a suction effect that facilitates the aspiration of sperm into the uterus.

Slide 6. Cytology/practical/72.html">Cross section of a human oviduct (fallopian tube) (Fig. 76).

Low magnification. Examine and draw the slide. The wall of the oviduct consists of three layers: mucosal, muscular, and serosal.

The mucous membrane forms longitudinal folds that project deeply into the lumen of the oviduct, transforming its passage into a system of intricate clefts. The epithelium of the mucosa is simple columnar and comprises two types of cells. Most cells bear cilia that beat toward the uterus. Interspersed among the ciliated cells are secretory cells that produce mucus.

The muscular coat is composed of two layers of Smooth Muscle tissue: an inner circular layer and an outer longitudinal layer.

The serosa has a typical Structure. The wall of the oviduct is rich in blood vessels.

Label on the drawing: 1) mucosal layer: a) mucosal folds, b) epithelium, c) lamina propria, d) blood vessels; 2) muscular layer: a) circular layer, b) longitudinal layer, c) blood vessels; 3) serosal layer: a) mesothelium, b) connective tissue, c) blood vessels; 4) lumen of the oviduct.

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Fig. 76. Cross section of a human oviduct. Hematoxylin-eosin stain. x 40:

1 — mucosa; 2 — simple columnar ciliated epithelium; 3 — lamina propria of the mucosa; 4 — muscular coat (inner circular layer); 5 — muscular coat (outer longitudinal layer); 6 — serosa

Slide 7. Section of the uterus during relative rest (Fig. 77).

Low magnification. Examine and draw the slide. The endometrium is represented by a simple columnar epithelium and a connective tissue lamina containing uterine glands in the form of straight or slightly tortuous epithelial tubules. The myometrium is built of smooth muscle layers. The perimetrium is the serosal coat.

Fig. 77. Section of the uterus during relative rest. Hematoxylin-eosin stain. x 100:

1 — mucosa (endometrium: a — functional layer of the mucosa; b — basal layer of the mucosa); 2 — muscular coat (myometrium); 3 — columnar epithelium; 4 — uterine mucosal crypts (glands); 5 — lamina propria of the mucosa; 6 — blood vessels

Label on the drawing: 1) mucosa — endometrium: a) epithelium; b) connective tissue lamina propria with uterine glands (simple tubular); 2) muscular coat — myometrium; 3) serosal coat — perimetrium: a) mesothelium; b) connective tissue; c) blood vessels.

Slide 8. Section of the uterus in the premenstrual period (Fig. 78).

Low magnification. Examine and draw the specimen.

The endometrium is thick, lined with a simple ciliated columnar epithelium. Mucous secretory cells are occasionally found among the ciliated cells.

The lamina propria of the mucosa contains decidual cells and extensively developed uterine glands that are tortuous and branched at their ends. The blood vessels are dilated and congested with blood.

Fig. 78. Cross section of the uterus during the premenstrual phase. Hematoxylin and eosin stain, x 100:

1 — mucosa (endometrium: a — functional layer; b — epitheliocytes; c — basal layer containing blood vessels engorged with blood, and corkscrew-twisted uterine glands in a state of active secretion); 2 — muscular coat of the uterus (myometrium) with dilated vessels; 3 — serosa

In this phase, the mucosa is divided into a thicker functional layer facing the uterine lumen and a thin basal layer adjacent to the muscular coat. The morphological boundary between the layers is indistinct and lies approximately at the level of the Fundus of the uterine glands.

During the menstrual phase, the functional layer is demarcated, breaks down, and is shed from the body. The basal layer remains intact and persists into the postmenstrual phase (proliferative phase), serving as the source for endometrial regeneration.

The myometrium and perimetrium exhibit typical histological structure.

Label the following on the diagram: 1) functional layer: a) epithelium; b) uterine glands; c) connective tissue; d) blood vessels.