Reproductive System Terms

Androgens: Generic term for the male sex hormones, such as testosterone and dihydrotestosterone.

Androgen binding protein (ABP): A carrier protein secreted by sustentacular (Sertoli) cells that maintains high high levels of testosterone in the testes, which enhances spermatogenesis in the seminiferous tubules and sperm maturation in the epididymis.

Bulbourethral glands: Paired accessory reproductive glands in the male, lying inferior to the prostate on either side of the urethra; that release secretions into the spongy urethra prior to ejaculation, which contain alkaline fluid that neutralizes acid in the male urethra, and mucus for lubrication. Also called Cowper's glands.

Clitoris: A cylindrical, erectile body in the anterior labia minora of the female; it is homologous to the male penis.

Corpus albicans: A white fibrous patch in the ovary that forms after the corpus luteum regresses.

Corpus luteum: The yellow endocrine body formed in the ovary at the site of a ruptured vesicular (Graafian) follicle immediately after ovulation that secretes progesterone, estrogens, and relaxin.

Ejaculation: The reflex ejection or expulsion of semen from the penis.

Estrogens: Female sex hormones produced by the ovaries; governs appearance of secondary sex characteristics and maintenance of female reproductive structures, regulates the menstrual cycle, stimulates development of oocytes, and reduces bone resorption.

Follicle-stimulating hormone (FSH): Hormone produced by the anterior pituitary gland; in females it stimulates the maturation of ovarian follicles and secretion of estrogen; in males it stimulates spermatogenesis and enhances production of androgen-binding protein (ABP) by sustentacular (Sertoli) cells. Also called follitropin.

Gamete: A male or female reproductive cell; a sperm cell or secondary oocyte.

Genitalia: The internal and external reproductive organs.

Gonad: Primary reproductive organ that produces gametes and hormones; the male testes and the female ovaries.

Gonadotropins: The gonad-stimulating hormones, such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH) which are secreted by the anterior pituitary, or human chorionic gonadotropin (hCG) which is secreted by the placental trophoblastic cells of the embryo. Also called gonadotropic hormones.

Greater vestibular glands: A pair of glands on either side of the vaginal orifice that secrete a mucoid lubricant and open by a duct into the space between the hymen and the labia minora. Also called Bartholin glands.

Inhibin: A hormone that inhibits the release of follicle-stimulating hormone (FSH) by the anterior pituitary; in females, it is secreted by granulosa cells in the ovary; in males, it is secreted by sustentacular (Sertoli) cells in the testis.

Interstitial cells: The cells in the testis that secretes testosterone; located in the connective tissue between seminiferous tubules. Also called Leydig cell.

Labia: Lip-shaped structures in the external female genitalia; the labia majora are two longitudinal folds of skin extending downward and backward from the mons pubis of the female; the labia minora are two small folds of mucous membrane lying medial to the labia majora of the female.

Ligaments of uterus: Dense fibrous connective tissue that supports the uterus and ovaries: the broad ligament is a peritoneal fold that attaches the lateral uterus to the pelvic wall, and contains the suspensory ligament that attaches the ovary to the pelvic wall and the mesovarium that covers the ovary, the ovarian ligament connects the ovary to the lateral surface of the uterus, the round ligament is attached near the opening of the uterine tube and passes through the inguinal canal to the labia majora, and the uterosacral ligament connects the cervix to

the sacrum.

Luteinizing hormone (LH): Anterior pituitary hormone. In females, it stimulates ovulation, formation of the corpus luteum, and secretion of progesterone. In males, it stimulates interstitial cells to secrete testosterone and is also called interstitial cell-stimulating hormone (ICSH). LH is also called lutropin

Male duct system: Accessory reproductive organs that produce, mature, store, and transport sperm from the testes to the exterior; includes the seminiferous tubules which produce sperm, the tubulus rectus, rete testis, efferent ductules, and epididymis which matures sperm, the ductus (vas) deferens which transports sperm from the testis to the prostate, the ejaculatory duct, and prostatic urethra which runs through the prostate, and the spongy urethra which runs through the penis.

Mammary glands: The milk secreting organs lying within the female breast; the milk producing alveolar glands develop only during pregnancy and remain active until weaning.

Meiosis: A special process of cell division that produces gametes in the primary reproductive organs; it involves two consecutive nuclear divisions that produce four genetically different cells with the haploid (n) number of chromosomes.

Menarche: The first menses (menstrual flow) and beginning of ovarian and uterine cycles.

Menopause: The termination of the menstrual cycles.

Menstrual cycle: The period that lasts an average of 28 days, in which ovarian follicles mature, then an oocyte is ovulated and enters the uterine tube; on day 1 the menstrual flow begins, after which a series of hormone-induced changes occur in the endometrium of a nonpregnant female, which prepares the lining of the uterus to receive a blastocyst. Also called the uterine cycle.

Menstruation: Periodic discharge of blood, tissue fluid, mucus and epithelial cells, which usually lasts for 3 to 5 days; caused by a sudden reduction in estrogens and progesterone. Also called the menstrual phase or menses.

Mitosis: The process of somatic reproduction of cells; it involves one nuclear division that produces two genetically identical daughter cells with the diploid (2n) number of chromosomes.

Oocyte: Immature female gamete.

Oogenesis: Formation and development of oocytes (female gametes).

Oogonium: Diploid stem cell in the fetal ovary that undergoes oogenesis to form primary oocytes.

Ovarian cycle: Monthly cycle of follicle development, ovulation, and corpus luteum formation in an ovary.

Ovarian follicle: The general name for an oocyte surrounded by follicular cells in various stages of development; a primordial follicle contains a primary oocyte that is arrested in Prophase I, and is surrounded by one layer of squamous follicle cells; a primary follicle contains a growing primary oocyte that is initially surrounded by one layer of cuboidal follicle cells that grow into two layers of granulosa cells; a secondary follicle contains a primary oocyte, which is coated by an extracellular glycoprotein layer called the zona pellucida, and is surrounded by several layers of granulosa cells, then the follicle becomes encased by a new layer of cells called the theca folliculi, estrogen is secreted, and small fluid-filled spaces begin to appear; a vesicular follicle (Graafian or antral follicle) initially contains a primary oocyte that completes Meiosis I but is arrested in Metaphase II and becomes a secondary oocyte which is surrounded by the corona radiata, a central fluid-filled cavity forms called an antrum, and the theca folliculi and granulosa cells secrete large amounts of estrogen.

Ovary: The primary sex organ of the female; the gonad that produces oocytes and secretes hormones, such as the estrogens, progesterone, inhibin, and relaxin.

Ovulation: The rupture of a vesicular (Graafian) follicle with discharge of a secondary oocyte, with its supporting cells, into the pelvic cavity.

Ovum: An imprecise term for an egg cell, which been applied to various stages of development from the primary oocyte to the implanting blastocyst.

Papanicolaou test: A cytological staining test for the detection and diagnosis of premalignant and malignant conditions of the female genital tract; cells scraped from the epithelium of the cervix of the uterus are examined microscopically. Also called a Pap test or Pap smear.

Penis: The male organ of copulation and urination, which is formed of three columns of erectile tissue; the dorsal side has two lateral columns called corpora cavernosa, and the ventral side has one medial column called corpus spongiosum that surrounds the spongy urethra and is continuous with the extremity called the glans penis.

Progesterone: A female sex hormone produced by the ovaries that helps prepare the endometrium of the uterus for implantation of a fertilized ovum, and the mammary glands for milk secretion. Also called pregnancy hormone.

Prostate gland: A doughnut-shaped accessory reproductive gland in the male, lying inferior to the urinary bladder that surrounds the superior portion of the male urethra; it secretes a milky fluid into the prostatic urethrea that activates sperm, with citric acid and enzymes that will break down clots and mucus.

Puberty: The time of life during which the secondary sex characteristics begin to appear and the capability for sexual reproduction is possible; usually occurs between the ages of 10 and 17.

Relaxin: A hormone secreted by the corpus luteum and placenta during pregnancy; it facilitates the birth process by softening and expanding the pubic symphysis and cervix, and it inhibits uterine contractions that could cause natural abortion.

Scrotum: A skin-covered external pouch that contains the testes, their accessory structures, and the dartos smooth muscles that cause the scrotal skin to contract and wrinkle when the environmental temperature is cold.

Secondary sex characteristics: Anatomic features of the male or female body that develops at puberty under the influence of sex hormones, but is not directly involved in sexual reproduction; examples are body hair distribution, voice pitch, pattern of bone growth, muscle development, body shape, etc.

Semen: A fluid discharged at ejaculation by a male that consists of a mixture of sperm and the secretions of the seminiferous tubules, seminal vesicles, prostate, and bulbourethral (Cowper's) glands.

Seminal vesicles: Paired accessory reproductive glands in the male, lying posterior and inferior to the urinary bladder and anterior to the rectum, that secrete a viscous alkaline fluid into the ejaculatory duct that neutralize acid, and contains vitamin C and fructose for ATP production by sperm, a coagulating enzyme to clot the semen after ejaculation, and prostaglandins for sperm motility and viability and to stimulate uterine contractions.

Seminiferous tubule: A tightly coiled duct located in the lobules of the testis, where spermatogenesis occurs.

Sperm: Male gamete that contains three regions: the head, with the nucleus and acrosome filled with digestive enzymes, the midpiece with mitochondria, and the tail, which is a flagellum. Also called spermatozoa.

Spermatic cord: A supporting structure formed around the ductus (vas) deferens and its associated structures, extending from the deep inguinal ring through the inguinal canal into the scrotum; it contains the cremaster muscles that elevate the testes when the environmental temperature is cold.

Spermatogenesis: The formation and development of sperm in the seminiferous tubules of the testes.

Spermatogonium: Diploid stem cell in the testis that undergoes spermatogenesis to form sperm.

Spermiogenesis: The maturation of spermatids into sperm.

Sustentacular cells: Supporting cells in the seminiferous tubules that secretes the hormone inhibin and fluid for supplying nutrients to sperm, removes excess cytoplasm from spermatogenic cells, and mediates the effects of FSH and testosterone on spermatogenesis. Also called Sertoli cells.

Testis: The primary sex organ of the male; the gonad that produces sperm and the hormones testosterone and inhibin. Also called testicle.

Testosterone: A male sex hormone (androgen) secreted by interstitial cells (Leydig cells) of the mature testes; encourages development of male secondary sex characteristics, and stimulates the development of sperm and activity of the accessory male sex organs.

Tunica albuginea: In females, a thin capsule of the ovary deep to the germinal epithelium; in males, a dense white fibrous capsule covering a testis.

Uterine tube: Duct that transports an oocyte or zygote from the ovary to the uterus; it consists of the infundibulum (funnel-like expansion) which is surrounded by fimbriae (finger-like projections with cilia), the wide ampulla, and the narrow isthmus that enters the uterine fundus. Also called the fallopian tube or oviduct.

Uterus: The hollow muscular organ in females that is the site of menstruation, implantation of the embryo, development of the fetus, and labor; it is divided into several regions: the cervix is the inferior neck that projects into the vagina; the body is the main portion; the fundus is the rounded superior region and opens into the uterine tubes; the uterine walls contain three layers: the perimetrium is the serosa, the myometrium is the smooth muscle layer, and the endometrium is the mucous membrane lining that contains a stratum functionalis which changes in response to ovarian hormone cycles and is shed during menstruation, and a stratum basalis which forms a new stratum functionalis after menstruation. The uterus is also called the womb.

Vagina: A muscular, tubular organ that leads from the uterus to the vestibule, situated between the urinary bladder and the rectum of the female. Also called the birth canal.