Ovary Structure The tissues of an ovary can be divided into an inner medulla and an outer cortex The ovarian medulla is mostly composed of loose connective tissue and contains many blood vessels, lymphatic vessels, and nerve fibers The ovarian cortex consists of more compact tissue and has a granular appearance due to tiny masses of cells called ovarian follicles

Oogenesis The process of egg cell formation Zygote Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Zygote 46 chromosomes, 23 from sperm cell and 23 from egg cell (each chromatid now an independent chromosome) Secondary oocyte Second meiotic division Fertilization First meiotic division Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (23 chromosomes, each with 2 chromatids) Primary oocyte Sperm nucleus Sperm cell (23 chromosomes) Second polar body degenerating (46 chromosomes, each with 2 chromatids) (b) Courtesy of R.J. Blandau (a) First polar body (23 chromosomes, each with 2 chromatids) First polar body degenerating Second meiotic division Polar bodies degenerating

Follicle Maturation At puberty, the anterior pituitary gland secretes increased amounts of FSH, and the ovaries enlarge in response With each reproductive cycle, some of the primordial follicles mature Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Theca externa Theca interna Primordial follicles Granulosa cells Fluid-filled antrum Corona radiata Zona pellucida Primary oocyte Secondary oocyte Maturing follicle (a) (b) b: © The McGraw-Hill Companies, Inc./Al Telser, photographer © The McGraw-Hill Companies, Inc./Al Telser, photographer

Follicle Maturation As many as twenty primary follicles may begin maturing at any one time One dominant follicle usually out-grows the others Typically only the dominant follicle fully develops and the others degenerate

Ovulation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. As a follicle matures, its primary oocyte undergoes meiosis I, giving rise to a secondary oocyte and a first polar body The process of ovulation releases these cells from the follicle Uterine tube Secondary oocyte Ovary © 2007 Landrum B. Shettles

Vagina A fibromuscular tube that conveys uterine secretions, receives the penis during intercourse, and provides an open channel for offspring Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glans of Clitoris Mons pubis Labium majus Urethral orifice Vestibule Vaginal orifice Labium minus Opening of vestibular gland Perineum Anus

Female External Reproductive Organs The female external reproductive organs surround the openings of the urethra and vagina and is known as the vulva, and include: Labia majora Labia minora Clitoris Vestibular glands Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glans of Clitoris Mons pubis Labium majus Urethral orifice Vestibule Vaginal orifice Labium minus Opening of vestibular gland Perineum Anus

Labia Majora Rounded folds of adipose tissue and skin Enclose and protect the other external reproductive parts Ends form a rounded elevation over the symphysis pubis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Clitoris Mons pubis Urethral orifice Labium majus V estibule Labium minus Vaginal orifice Opening of vestibular gland Perineum Anus

Labia Minora Flattened, longitudinal folds between the labia majora Well supplied with blood vessels Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Clitoris Mons pubis V estibule Perineum Anus Urethral orifice Vaginal Labium majus minus Opening of vestibular gland

Clitoris Glans of clitoris is the small projection at the anterior end of the vulva Analogous to the male penis Composed of two columns of erectile tissue Root is attached to the sides of the pubic arch Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Clitoris Mons pubis V estibule Perineum Anus Urethral orifice Vaginal Labium majus minus Opening of vestibular gland

Vestibule Space between the labia minora that encloses the vaginal and the urethral openings The vestibular glands secrete mucus into the vestibule during sexual stimulation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Clitoris Mons pubis V estibule Perineum Anus Urethral orifice Vaginal Labium majus minus Opening of vestibular gland

Female Sex Hormones + – + Hypothalamus GnRH Pituitary gland Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hypothalamus + GnRH – Pituitary gland Estrogens inhibit oversecretion of gonadotropins FSH, LH (gonadotropins) Increased vascularization of the skin Breasts develop Accessory reproductive organs enlarge Bloodstream Stimulates endometrium of uterus to thicken Increased deposition of adipose tissue in breasts, thighs, and buttocks Gonadotropins + Estrogens Release into bloodstream Ovaries Stimulation Inhibition