Chapter Summary

I. OVARY

A. Cortex

The cortex of the ovary is covered by a modified mesothelium, the germinal epithelium. Deep to this simple cuboidal to simple squamous epithelium is the tunica albuginea, the fibrous connective tissue capsule of the ovary. The remainder of the ovarian connective tissue is more cellular and is referred to as the stroma. The cortex houses ovarian follicles in various stages of development.

1. Primordial Follicles

Primordial follicles consist of a primary oocyte surrounded by a single layer of flattened follicular (granulosa) cells.

2. Primary Follicles

a. Unilaminar Primary Follicles

Consist of a primary oocyte surrounded by a single layer of cuboidal follicular cells

b. Multilaminar Primary Follicles

Consist of a primary oocyte surrounded by several layers of follicular cells. The zona pellucida is visible. The theca interna is beginning to be organized.

3. Secondary (Vesicular) Follicle

The secondary follicle is distinguished from the primary multilaminar follicle by its larger size,by a well-established theca interna and theca externa, and especially by the presence of follicular fluid in small cavities formed from intercellular spaces of the follicular cells. These fluidfilled cavities are known as Call-Exner bodies.

4. Graafian (Mature) Follicles

The Graafian follicle is very large; the Call-Exner bodies have coalesced into a single space, the antrum, filled with follicular fluid. The wall of the antrum is referred to as the membrana granulosa, and the region of the oocyte and follicular cells jutting into the antrum is the cumulus oophorus. The single layer of follicular cells immediately surrounding the oocyte is the corona radiata. Long apical processes of these cells extend into the zona pellucida. The theca interna and theca externa are well developed; the former displays numerous cells and capillaries, whereas the latter is less cellular and more fibrous.

5. Atretic Follicles

Atretic follicles are in the state of degeneration. They are characterized in later stages by the presence of fibroblasts in the follicle and a degenerated oocyte.

B. Medulla

The medulla of the ovary is composed of a relatively loose fibroelastic connective tissue housing an extensive vascular supply, including spiral arteries and convoluted veins.

C. Corpus Luteum

Subsequent to the extrusion of the secondary oocyte with its attendant follicular cells, the remnant of the Graafian follicle becomes partly filled with blood and is known as the corpus hemorrhagicum. Cells of the membrana granulosa are transformed into large granulosa lutein cells. Moreover, the cells of the theca interna also increase in size to become theca lutein cells, although they remain smaller than the granulosa lutein cells.

D. Corpus Albicans

The corpus albicans is a corpus luteum that is in the process of involution and hyalinization. It becomes fibrotic, with few fibroblasts among the intercellular materials. Eventually, the corpus albicans will become scar tissue on the ovarian surface.

II. GENITAL DUCTS

A. Oviduct

1. Mucosa

The mucosa of the oviduct is highly folded in the infundibulum and ampulla. It is composed of a loose, cellular connective tissue, lamina propria, and a simple columnar epithelial lining. The epithelium is composed of peg cells and ciliated cells.

2. Muscularis

The muscle coat is composed of an inner circular and an outer longitudinal smooth muscle layer.

3. Serosa

The oviduct is invested by a serosa.

B. Uterus

1. Endometrium

The endometrium is subdivided into a basal and a functional layer. It is lined by a simple columnar epithelium.The lamina propria varies with the phases of the menstrual cycle.

a. Follicular Phase

The glands are straight and display mitotic figures, and the helical arteries grow into the functional layer.

b. Luteal Phase

Glands become tortuous, and the helical arteries become coiled. The lumina of the glands accumulate secretory products. Fibroblasts enlarge and accumulate glycogen.

c. Menstrual Phase

The functional layer is desquamated, and the lamina propria displays extravasated blood.

2. Myometrium

The myometrium is thick and consists of three poorly delineated smooth muscle layers: inner longitudinal, middle circular, and outer longitudinal. During pregnancy, the myometrium increases in size as a result of hypertrophy of existing muscle cells and the accumulation of new smooth muscle cells.

3. Serosa

Most of the uterus is covered by a serosa; the remainder is attached to surrounding tissues by an adventitia.

C. Placenta

1. Decidua Basalis

The decidua basalis, the maternally derived endometrial layer, is characterized by the presence of large, glycogenrich decidual cells. Coiled arteries and straight veins open into the labyrinth-like intervillous spaces.

2. Chorionic Plate and Villi

The chorionic plate is a region of the chorionic sac of the fetus from which chorionic villi extend into the intervillous spaces of the decidua basalis. Each villus has a core of

fibromuscular connective tissue surrounding capillaries

(derived from the umbilical vessels). The villus is covered by trophoblast cells. During the first half of pregnancy, there are two layers of trophoblast cells, an inner cuboidal layer of cytotrophoblasts and an outer layer of syncytiotrophoblasts. During the second half of pregnancy, only the syncytiotrophoblasts remain. However, at points where chorionic villi are anchored into the decidua basalis, cytotrophoblasts are present.

F E M A L E R E P R O D U C T I V E S Y S T E M 433

D. Vagina

1. Mucosa

The vagina is lined by a stratified squamous nonkeratinized epithelium. The lamina propria, composed of a fibroelastic connective tissue, possesses no glands. The mucosa is thrown into longitudinal folds known as rugae.

2. Submucosa

The submucosa is also composed of a fibroelastic type of connective tissue housing numerous blood vessels.

3. Muscularis

The muscularis is composed of interlacing bundles of smooth muscle fibers. Near its external orifice, the vagina is equipped with a skeletal muscle sphincter.

4. Adventitia

The vagina is connected to surrounding structures via its adventitia.

E. Mammary Glands

1. Resting Gland

The resting gland is composed mainly of dense irregular collagenous connective tissue interspersed with lobules of adipose tissue and numerous ducts. Frequently, at the blind ends of ducts, buds of alveoli and attendant myoepithelial cells are present.

2. Lactating Gland

The mammary gland becomes active during pregnancy and lactation. The expanded alveoli that form numerous lobules are composed of simple cuboidal cells, resembling the thyroid gland. However, the presence of ducts and myoepithelial cells provides distinguishing characteristics. Alveoli and the lumen of the ducts may contain a fatty secretory product.

3. Areola and Nipple

The areola is composed of thin, pigmented epidermis displaying large apocrine areolar glands. Additionally, sweat and large sebaceous glands are also present. The dermis presents numerous smooth muscle fibers. The nipple possesses several minute pores representing the distal ends of lactiferous ducts. These ducts arise from lactiferous sinuses, enlarged reservoirs at the base of the nipple. The epidermis covering the nipple is thin, and the dermis is richly supplied by smooth muscle fibers and nerve endings. Although the nipple possesses no hair follicles or sweat glands, it is richly endowed with sebaceous glands.

CHAPTER OUTLINE

Graphics

Graphic 18-1 Male Reproductive System p. 440 Graphic 18-2 Spermiogenesis p. 441

Tables

Table 18-1 Functions of Sertoli Cells

Plates