The Female Reproduction System

The ovaries (slide #79) are paired gametogenic and endocrine glands. Each ovary consists of a cortex containing follicles with oocytes and a medulla with prominent blood and lymph vessels. Examine both odd and even slides of the ovary. The flattened or cuboidal germinal epithelium (mesothelium) on the surface of the ovary is easily torn loose and is often missing (best seen on #79 even). Underlying the germinal epithelium is the tunica albuginea which consists of a thin layer of dense, circular connective tissue with fibers running roughly parallel to the surface. The deeper cortical area contains the follicles. The cortical stroma is highly cellular, and the elongated stromal cells are arranged in wavy patterns or whorls.

The small primordial follicles measure about 30 µm ( the diameter of four to five RBCs) and have a single flattened layer of follicular cells around the oocyte.

When follicle growth begins, the flat follicular cells become cuboidal. The zona pellucida begins to form between the oocyte and the follicular cells. The follicular cells become multilayered, and the surrounding stromal cells begin to form the theca interna and the theca externa. The boundary between the two theca layers is indistinct and the theca externa blends into the surrounding stroma.

Few follicles, grow up to the point of ovulation. Most begin to grow and then degenerate. In young follicles the oocytes degenerate first. In secondary follicles, early changes include the presence of follicular cells floating in the antral fluid and the invasion of fine blood vessels and connective tissue into the granulosa cell layer. In these follicles the granulosa cells degenerate first, then the oocyte; the degenerating tissue is replaced by connective tissue, macrophages, and capillaries. The follicle collapses, and the follicular basement membrane becomes wavy and thickens into a mass of hyaline (i.e., refractile) material called the glassy membrane. Locate the glassy membrane, a wavy, refractile, pink-staining line, usually U-shaped or circular. This and its associated cells are terminal remnants of atretic follicles. The process of atresia can take several months.

The corpus luteum of slide #80 is a body about one inch in diameter with an angular cavity. With the reverse ocular or naked eye, examine its shape and size. With 10x, note that the granulosa lutein cells derived from the follicular (granulosa) cells are the predominant and largest cell type.

The theca lutein cells, derived from the theca interna, are smaller, fewer in number, and are located peripheral to the granulosa lutein cells. Groups of these cells may be seen where there are connective tissue infoldings. They appear as groups of crowded rounded nuclei with empty looking cytoplasm (best seen on #80 odd). Under higher magnification, compare the granulosa lutein cells with the theca lutein cells. Note the abundance of capillaries among both cell types. At the end of menstruation, the corpus luteum involutes, its cells degenerate, yellowish lipochrome pigment is seen, and the area is invaded by fibroblasts and macrophages. Over the succeeding months, these cells become pyknotic, and the area is eventually changed into a pale scarred mass called the corpus albicans (white body). This sinks deeper into the ovary over months or years. On slide #81, examine a large, fairly recent corpus albicans still reflecting the shape of the corpus luteum. On slide #79 odd (ovary), a small, shrunken, more fibrous, and hence, older corpus albicans may be found.

Slide #83 (even and odd) both contain sections of infundibulum and ampulla. It can be difficult to tell where the infundibulum ends and the ampulla begins. Slide #83 odd is a longitudinal section through the infundibulum and ampulla. Since the tube is twisted, portions of the tube may be in oblique or cross-section. With the reverse ocular or scanning lens, locate the infundibulum with its fimbria at the extreme end of the tissue. At the opposite end is the ampulla. Notice the gradual decrease in size of both the lumen and the mucosal folds and the gradual increase in the thickness of muscle coat. Examine the epithelium and notice the patches of ciliated cells.

On slide #82 (odd and even), find the cross-section of the isthmus (round in outline) and note that the folds of the mucous membrane are relatively simple, and their lamina propria is very vascular. The mucosal folds are covered by columnar epithelium with only a few ciliated cells. The muscle wall is conspicuous with a thick inner circular and a thinner outer longitudinal component. At the outer edges of the oviduct, locate the covering serosal epithelium (may be absent), and note that the serosa is thick and contains abundant blood vessels.

The intramural (interstitial) portion of the oviduct is found within the myometrium of the uterine wall. Using the scanning lens, find on slide #82 (even, up to box #186 only) the small lumen of the intramural duct, which is lined by columnar epithelium. There may be blood vessels nearby in the uterine tissue with a lumen as large or larger lined by squamous epithelium. Note the size of the oviduct lumen, the near absence of mucosal folds and under higher magnification, the scarcity of ciliated cells. The intramural oviduct is encircled by its own muscular coat which can be distinguished from the multi-oriented uterine muscle. This slide also contains a section through the isthmus.

Examine a uterus in the proliferative or follicular phase on slide #85. (Slide #85 is late proliferative). With the reversed ocular, locate the endometrium and choose an area where the glands appear to be cut in longitudinal section. Examine the full thickness of the endometrium noting that the stroma is more compact towards the stratum basalis. Under higher magnification, note that a columnar epithelium (with a few scattered ciliated cells) lines the surface and the glands. The glands are straight or slightly wavy. The myometrium is composed of three indistinct layers of muscle.

Examine a uterus in the secretory or luteal phase (slide #86), both odd and even should be seen. With the reversed ocular and higher magnification, locate the endometrium, (on one side of the tissue block) with its characteristically dilated or sacculated glands. Under higher magnification notice that the stroma is edematous (increased interstitial fluid) in slide #86 odd, and shows large empty spaces. Immediately adjacent to the myometrium, the bases of the glands are located in the stratum basalis.

Slide #87 even is a late menstrual uterus. The free surface of the endometrium has lost its epithelium, and the stroma and broken glands and blood vessels protrude. Little remains of the stratum functionalis. Most of the glands and stroma belong to the stratum basalis and will not be shed. There is no evidence of epithelialization of the denuded surface, so this section was taken before the end of the menstrual period. Slide #87 odd is of a menstrual uterus just after the beginning of menstruation. In some areas the epithelium is still intact though the underlying stroma is swollen with extravasated blood.

Slide #88 (odd and even), is a section through one side of the cervix. The lumenal surface of the endocervix (region of the cervical canal) is lined with columnar epithelium. At or near where the tissue curves (region of the external os) the epithelium changes from simple columnar to stratified squamous (region of the ectocervix). The highest incidence of gynecological cancers occurs in the region of the external os. In the region of the endocervix, there are several cervical glands (these are best seen on slide #88 odd). Some glands project under the stratified squamous epithelium of the ectocervix and may show cystic dilations. The muscle of the cervix is relatively deficient compared to the rest of the uterus and arranged in irregular bundles and intermingled with dense connective tissue. Note the abundance of blood vessels.

The vagina is a distensible fibromuscular tube continuous above with the cervix and opening into the vestibule of the female external genitalia. The wall of the vagina consists of three layers: mucosa, muscularis, and adventitia. Slide #89 has only the mucosa and part of the muscularis.

Slide #91 -(NOTE: on slide #91 odd, there is a large encapsulated area with loose connective tissue, degenerated glands, and enlarged cystic ducts and glands. This is a fibroadenoma. Study the rest of the tissue which is normal). The lobes of the mammary gland are further subdivided into lobules. On slide #91 locate the lobules which are separated by dense interlobular connective tissue and fat cells. The epithelial cells within the lobule are chiefly duct elements and are contained in a loose connective tissue which lacks fat cells. Interlobular ducts can be observed in the dense interlobular connective tissue.

On slide #92, (examine even and odd) notice a tremendous increase in the number of lobules. Within the lobules, secretory alveoli are seen in varying functional states. In some places the secretory portions are filled with milk (wide lumen and thin lining cells) and in other areas they are not (lumen narrow and epithelial height is increased). Some of the epithelium appears vacuolated due to lipid extraction during histological preparation. Try to find the nuclei of a myoepithelial cell (within the basement membrane). Note the presence of plasma cells within the intralobular connective tissue and the decrease in interlobular connective tissue. How can you differentiate the lactating mammary gland from the thyroid gland?

Slide #93 with reverse ocular examine the general topography of the nipple. Note the dark staining epidermal covering, dense connective tissue stroma, and the lactiferous ducts. Under low power observe the highly folded stratified squamous epithelium, dermal papillae and sebaceous glands. At higher magnification observe the pigmentation in the basal cells of the epithelium. Bundles of smooth muscle run in various planes in the stroma, and the lactiferous ducts can be seen as large, elongated spaces lined with one or two layers of columnar epithelium.