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Editor's Notes

• #3: he female reproductive system consists of the paired ovaries and oviducts (or uterine tubes), the uterus, the vagina, and the external genitalia VETIBULE PARAURETHRAL GLANDS (SKENESl BARTHOLIN GLNADS
• #4: This system produces the female gametes (oocytes), provides the environment for fertilization, and holds the embryo during its complete development through the fetal stage until birth. As with male gonads, the ovaries produce steroidal sex hormones that control organs of the reproductive system and influence other organs.
• #5: he female reproductive system consists of the paired ovaries and oviducts (or uterine tubes), the uterus, the vagina, and the external genitalia (Figure 22–1). This system produces the female gametes (oocytes), provides the environment for fertilization, and holds the embryo during its complete development through the fetal stage until birth. As with male gonads, the ovaries produce steroidal sex hormones that control organs of the reproductive system and influence other organs.
• #6: Ovaries are almond-shaped bodies approximately 3-cm long, 1.5-cm wide, and 1-cm thick. Each ovary is covered by a sim_x0002_ple cuboidal epithelium, the surface (or germinal) epithe_x0002_lium, continuous with the mesothelium and overlying a layer of dense connective tissue capsule, the tunica albuginea,
• #7: Most of the ovary consists of the cortex, a region with a stroma of highly cellular connective tissue and many ovarian follicles varying greatly in size after men_x0002_arche (Figure 22–1). The most internal part of the ovary, the medulla, contains loose connective tissue and blood vessels entering the organ through the hilum from mesenteries sus_x0002_pending the ova
• #8: An ovarian follicle consists of an oocyte surrounded by one or more layers of epithelial cells within a basal lamina.
• #9: An ovarian follicle consists of an oocyte surrounded by one or more layers of epithelial cells within a basal lamina.
• #10: The follicles that are formed during fetal life—primordial follicles—consist of a primary oocyte enveloped by a single layer of the flattened follicular cells (Figures 22–2b, 22–3, and 22–4). These follicles occur in the superficial ovarian cortex. The oocyte in the pri_x0002_mordial follicle is spherical and about 25 μm in diameter, with a large nucleus containing chromosomes in the first meiotic pro_x0002_phase. The organelles tend to be concentrated near the nucleus and include numerous mitochondria, several Golgi complexes, and extensive RER. The basal lamina surrounding the follicular cells marks a clear boundary between the follicle and the vascu_x0002_larized stroma and acts as a blood-follicle barrier.
• #11: Beginning in puberty with the release of follicle-stimulating hormone (FSH) from the pituitary, a small group of primor dial follicles each month begins a process of follicular growth. This involves growth of the oocyte, proliferation and changes in the follicular cells, as well as proliferation and differentia tion of the stromal fibroblasts around each follicle. Selection of the primordial follicles that undergo growth and recruit ment early in each cycle and of the dominant follicle destined to ovulate that month both involve complex hormonal bal ances and subtle differences among follicles in FSH receptor numbers, aromatase activity, estrogen synthesis, and other variables. Prompted by FSH, an oocyte grows most rapidly during the first part of follicular development, reaching a diameter of about 120 μm. Oocyte differentiation includes the following: ■ Growth of the cell and nuclear enlargement. ■Mitochondria becoming more numerous and uniformly distributed. ■ RER becoming much more extensive and Golgi com plexes enlarging and moving peripherally. ■ Formation of specialized secretory granules called corti cal granules containing various proteases. These lie just inside the oocyte’s plasma membrane and undergo exo cytosis early in fertilization. Follicular cells undergo mitosis and form a simple cuboi dal epithelium around the growing oocyte. The follicle is now called a unilaminar primary follicle (Figures 22–3 and 22–5a). The follicular cells continue to proliferate, forming a stratified follicular epithelium, the granulosa, in which the cells communicate through gap junctions. Follicular cells are now termed granulosa cells and the follicle is a multilami nar primary follicle (Figures 22–3 and 22–5b) still avascular and surrounded by a basement membrane. Between the oocyte and the first layer of granulosa cells of the growing primary follicle, extracellular material accu mulates as the zona pellucida, 5-10-μm thick and contain ing four glycoproteins secreted by the oocyte (Figures 22–5b and 22–6). The zona pellucida components ZP3 and ZP4 are important sperm receptors, binding specific proteins on the sperm surface and inducing acrosomal activation. Filopodia of granulosa cells and microvilli of the oocyte penetrate the zona pellucida, allowing communication between these cells via gap junctions. Stromal cells immediately outside each growing primary follicle differentiate to form the vascularized follicular theca (Gr. theca, outer covering), which subsequently differentiates further as two distinct tissues around the follicle (see Figures 22–3, 22–7, and 22–8): ■ A well-vascularized endocrine tissue, the theca interna, with typical steroid-producing cells secret ing androstenedione. This precursor molecule diffuses into the follicle through the basement membrane, and in the granulosa cells the enzyme aromatase con verts it to estradiol, an FSH-dependent function. This estrogen returns to the thecae and stroma around the follicle, enters capillaries, and is distributed through out the body, inducing the changes characteristic of puberty. ■ A more fibrous theca externa with fibroblasts and smooth muscle merges gradually with the surrounding stroma. Growing primary follicles can become involved in polycystic ovary syndrome (PCOS) that is characterized by enlarged ovaries with numerous cysts and an anovulatory state (with no follicles completing maturation successfully). The clinical presentation of this disorder is variable and the etiology is unclear, although increased androgen production by the ova ries or adrenals is likely involved. PCOS is a common cause of infertility in women
• #12: Beginning in puberty with the release of follicle-stimulating hormone (FSH) from the pituitary, a small group of primor dial follicles each month begins a process of follicular growth. This involves growth of the oocyte, proliferation and changes in the follicular cells, as well as proliferation and differentia tion of the stromal fibroblasts around each follicle. Selection of the primordial follicles that undergo growth and recruit ment early in each cycle and of the dominant follicle destined to ovulate that month both involve complex hormonal bal ances and subtle differences among follicles in FSH receptor numbers, aromatase activity, estrogen synthesis, and other variables. Prompted by FSH, an oocyte grows most rapidly during the first part of follicular development, reaching a diameter of about 120 μm. Oocyte differentiation includes the following: ■ Growth of the cell and nuclear enlargement. ■Mitochondria becoming more numerous and uniformly distributed. ■ RER becoming much more extensive and Golgi com plexes enlarging and moving peripherally. ■ Formation of specialized secretory granules called corti cal granules containing various proteases. These lie just inside the oocyte’s plasma membrane and undergo exo cytosis early in fertilization. Follicular cells undergo mitosis and form a simple cuboi dal epithelium around the growing oocyte. The follicle is now called a unilaminar primary follicle (Figures 22–3 and 22–5a). The follicular cells continue to proliferate, forming a stratified follicular epithelium, the granulosa, in which the cells communicate through gap junctions. Follicular cells are now termed granulosa cells and the follicle is a multilami nar primary follicle (Figures 22–3 and 22–5b) still avascular and surrounded by a basement membrane. Between the oocyte and the first layer of granulosa cells of the growing primary follicle, extracellular material accu mulates as the zona pellucida, 5-10-μm thick and contain ing four glycoproteins secreted by the oocyte (Figures 22–5b and 22–6). The zona pellucida components ZP3 and ZP4 are important sperm receptors, binding specific proteins on the sperm surface and inducing acrosomal activation. Filopodia of granulosa cells and microvilli of the oocyte penetrate the zona pellucida, allowing communication between these cells via gap junctions. Stromal cells immediately outside each growing primary follicle differentiate to form the vascularized follicular theca (Gr. theca, outer covering), which subsequently differentiates further as two distinct tissues around the follicle (see Figures 22–3, 22–7, and 22–8): ■ A well-vascularized endocrine tissue, the theca interna, with typical steroid-producing cells secret ing androstenedione. This precursor molecule diffuses into the follicle through the basement membrane, and in the granulosa cells the enzyme aromatase con verts it to estradiol, an FSH-dependent function. This estrogen returns to the thecae and stroma around the follicle, enters capillaries, and is distributed through out the body, inducing the changes characteristic of puberty. ■ A more fibrous theca externa with fibroblasts and smooth muscle merges gradually with the surrounding stroma. Growing primary follicles can become involved in polycystic ovary syndrome (PCOS) that is characterized by enlarged ovaries with numerous cysts and an anovulatory state (with no follicles completing maturation successfully). The clinical presentation of this disorder is variable and the etiology is unclear, although increased androgen production by the ova ries or adrenals is likely involved. PCOS is a common cause of infertility in women
• #13: Stromal cells immediately outside each growing primary follicle differentiate to form the vascularized follicular theca (Gr. theca, outer covering), which subsequently differentiates further as two distinct tissues around the follicle (see Figures 22–3, 22–7, and 22–8): ■ A well-vascularized endocrine tissue, the theca interna, with typical steroid-producing cells secret ing androstenedione. This precursor molecule diffuses into the follicle through the basement membrane, and in the granulosa cells the enzyme aromatase con verts it to estradiol, an FSH-dependent function. This estrogen returns to the thecae and stroma around the follicle, enters capillaries, and is distributed through out the body, inducing the changes characteristic of puberty. ■ A more fibrous theca externa with fibroblasts and smooth muscle merges gradually with the surrounding stroma. Growing primary follicles can become involved in polycystic ovary syndrome (PCOS) that is characterized by enlarged ovaries with numerous cysts and an anovulatory state (with no follicles completing maturation successfully). The clinical presentation of this disorder is variable and the etiology is unclear, although increased androgen production by the ova ries or adrenals is likely involved. PCOS is a common cause of infertility in women
• #14: Beginning in puberty with the release of follicle-stimulating hormone (FSH) from the pituitary, a small group of primor dial follicles each month begins a process of follicular growth. This involves growth of the oocyte, proliferation and changes in the follicular cells, as well as proliferation and differentia tion of the stromal fibroblasts around each follicle. Selection of the primordial follicles that undergo growth and recruit ment early in each cycle and of the dominant follicle destined to ovulate that month both involve complex hormonal bal ances and subtle differences among follicles in FSH receptor numbers, aromatase activity, estrogen synthesis, and other variables. Prompted by FSH, an oocyte grows most rapidly during the first part of follicular development, reaching a diameter of about 120 μm. Oocyte differentiation includes the following: ■ Growth of the cell and nuclear enlargement. ■Mitochondria becoming more numerous and uniformly distributed. ■ RER becoming much more extensive and Golgi com plexes enlarging and moving peripherally. ■ Formation of specialized secretory granules called corti cal granules containing various proteases. These lie just inside the oocyte’s plasma membrane and undergo exo cytosis early in fertilization. Follicular cells undergo mitosis and form a simple cuboi dal epithelium around the growing oocyte. The follicle is now called a unilaminar primary follicle (Figures 22–3 and 22–5a). The follicular cells continue to proliferate, forming a stratified follicular epithelium, the granulosa, in which the cells communicate through gap junctions. Follicular cells are now termed granulosa cells and the follicle is a multilami nar primary follicle (Figures 22–3 and 22–5b) still avascular and surrounded by a basement membrane. Between the oocyte and the first layer of granulosa cells of the growing primary follicle, extracellular material accu mulates as the zona pellucida, 5-10-μm thick and contain ing four glycoproteins secreted by the oocyte (Figures 22–5b and 22–6). The zona pellucida components ZP3 and ZP4 are important sperm receptors, binding specific proteins on the sperm surface and inducing acrosomal activation. Filopodia of granulosa cells and microvilli of the oocyte penetrate the zona pellucida, allowing communication between these cells via gap junctions. Stromal cells immediately outside each growing primary follicle differentiate to form the vascularized follicular theca (Gr. theca, outer covering), which subsequently differentiates further as two distinct tissues around the follicle (see Figures 22–3, 22–7, and 22–8): ■ A well-vascularized endocrine tissue, the theca interna, with typical steroid-producing cells secret ing androstenedione. This precursor molecule diffuses into the follicle through the basement membrane, and in the granulosa cells the enzyme aromatase con verts it to estradiol, an FSH-dependent function. This estrogen returns to the thecae and stroma around the follicle, enters capillaries, and is distributed through out the body, inducing the changes characteristic of puberty. ■ A more fibrous theca externa with fibroblasts and smooth muscle merges gradually with the surrounding stroma. Growing primary follicles can become involved in polycystic ovary syndrome (PCOS) that is characterized by enlarged ovaries with numerous cysts and an anovulatory state (with no follicles completing maturation successfully). The clinical presentation of this disorder is variable and the etiology is unclear, although increased androgen production by the ova ries or adrenals is likely involved. PCOS is a common cause of infertility in women
• #15: Primary follicles develop into secondary (antral) follicles as fluid-filled spaces merge to form the antrum. Follicular fluid contains hyaluronic acid, growth factors, and steroids. Granulosa cells form the cumulus oophorus and corona radiata, which move with the oocyte during ovulation. As primary follicles develop in the ovarian cortex, they move deeper and form small spaces filled with follicular fluid. These spaces merge to create a larger cavity called the antrum, transforming the follicle into a secondary or antral follicle. The follicular fluid contains hyaluronic acid, growth factors, plasminogen, fibrinogen, heparan sulfate proteoglycan, and high levels of steroids. As the antrum grows, granulosa cells around the oocyte form a structure called the cumulus oophorus, while cells directly adjacent to the zona pellucida become the corona radiata, which travels with the oocyte during ovulation. As the primary follicles grow, they move deeper in the ovarian cortex. Within such follicles small spaces appear between the granulosa layers as the cells secrete follicular fluid (or liquor folliculi). This fluid accumulates, the spaces enlarge and gradually coalesce, and the granulosa cells reor_x0002_ganize themselves around a larger cavity called the antrum, producing follicles now called secondary or antral follicles. Follicular fluid contains the large GAG hyaluronic acid, growth factors, plasminogen, fibrinogen, the anticoagulant heparan sulfate proteoglycan, and high concentrations of steroids (progesterone, andro_x0002_stenedione, and estrogens) with binding proteins. As the antrum develops, the granulosa cells around the oocyte form a small hillock, the cumulus oophorus, which protrudes into the antrum. The tightly adhering granulosa cells immediately surrounding the zona pellucida make up the corona radiata and accompany the oocyte when it leaves the ovary at ovulation.
• #16: Stromal cells immediately outside each growing primary follicle differentiate to form the vascularized follicular theca (Gr. theca, outer covering), which subsequently differentiates further as two distinct tissues around the follicle (see Figures 22–3, 22–7, and 22–8): ■ A well-vascularized endocrine tissue, the theca interna, with typical steroid-producing cells secret ing androstenedione. This precursor molecule diffuses into the follicle through the basement membrane, and in the granulosa cells the enzyme aromatase con verts it to estradiol, an FSH-dependent function. This estrogen returns to the thecae and stroma around the follicle, enters capillaries, and is distributed through out the body, inducing the changes characteristic of puberty. ■ A more fibrous theca externa with fibroblasts and smooth muscle merges gradually with the surrounding stroma. Growing primary follicles can become involved in polycystic ovary syndrome (PCOS) that is characterized by enlarged ovaries with numerous cysts and an anovulatory state (with no follicles completing maturation successfully). The clinical presentation of this disorder is variable and the etiology is unclear, although increased androgen production by the ova ries or adrenals is likely involved. PCOS is a common cause of infertility in women At higher magnification, a small part of the wall of an antral fol_x0002_licle shows the cell layers of the granulosa (G) next to the antrum (A), in which proteins have aggregated on cells in contact with the follicular fluid. The theca interna (TI) surrounds the follicle, its cells appearing vacuolated and lightly stained because of their cytoplasmic lipid droplets, a characteristic of steroid-producing cells. The overlying theca externa (TE) contains fibroblasts and smooth muscle cells and merges with the stroma (S). A base_x0002_ment membrane (BM) separates the theca interna from the granulosa, blocking vascularization of the latter. (X400; PT) FIGURE 22–9 Atresia. O A G Atresia or degeneration of a follicle can begin at any stage of follicular development and is shown here in a follicle that had already developed a large antrum. Atresia is characterized by apoptosis of follicle or granulosa cells (G) and autolysis of the oocyte, with macrophages entering the degenerating structure to clean up debris. Many apoptotic bodies are seen loose in the antrum (A) here and the cells of the corona radiata have already disappeared, leaving the degenerative oocyte (O) free within the antrum. (X200; PT) 22_Mescher_ch22_p460-489.indd 467 26/04/18 12:00 pm CHAPTER 22 The Female Reproductive System ■ Ovarie
• #17: PIC: A slightly more developed preovulatory follicle shows a very large single antrum (A) filled with follicular fluid in which the proteins formed a thin film during fixation. The oocyte (O) now projects into this fluid-filled cavity, still surrounded by tightly adherent granulosa cells, which now make up the corona radiata (CR). The corona radiata and oocyte are attached to the side of the follicle within a larger mass of granulosa cells called the cumulus oophorus (CO), which is continuous with the cells of the granulosa layer (G). Thecae interna (TI) and externa (TE) surround the whole follicle. (X100; PT)
• #18: PIC: A slightly more developed preovulatory follicle shows a very large single antrum (A) filled with follicular fluid in which the proteins formed a thin film during fixation. The oocyte (O) now projects into this fluid-filled cavity, still surrounded by tightly adherent granulosa cells, which now make up the corona radiata (CR). The corona radiata and oocyte are attached to the side of the follicle within a larger mass of granulosa cells called the cumulus oophorus (CO), which is continuous with the cells of the granulosa layer (G). Thecae interna (TI) and externa (TE) surround the whole follicle. (X100; PT)
• #19: The follicles that are formed during fetal life—primordial follicles—consist of a primary oocyte enveloped by a single layer of the flattened follicular cells (Figures 22–2b, 22–3, and 22–4). These follicles occur in the superficial ovarian cortex. The oocyte in the pri_x0002_mordial follicle is spherical and about 25 μm in diameter, with a large nucleus containing chromosomes in the first meiotic pro_x0002_phase. The organelles tend to be concentrated near the nucleus and include numerous mitochondria, several Golgi complexes, and extensive RER. The basal lamina surrounding the follicular cells marks a clear boundary between the follicle and the vascu_x0002_larized stroma and acts as a blood-follicle barrier.
• #20: he female reproductive system consists of the paired ovaries and oviducts (or uterine tubes), the uterus, the vagina, and the external genitalia (Figure 22–1). This system produces the female gametes (oocytes), provides the environment for fertilization, and holds the embryo during its complete development through the fetal stage until birth. As with male gonads, the ovaries produce steroidal sex hormones that control organs of the reproductive system and influence other organs.