The Reproductive Systems Chapter 21 The Reproductive Systems

Common Structures & Functions Systems adapted for development of sperm or ova followed by successful fertilization, development, and birth of offspring Sex hormones in both genders important in development of secondary sexual characteristics and normal reproductive system activity

Male Reproductive System Structural plan - organs classified as essential or accessory Essential organs of reproduction are the gonads (testes), which produce sex cells (sperm or spermatozoa) Accessory organs of reproduction Ducts - passageways that carry sperm from testes to exterior Sex glands - produce protective and nutrient solution for sperm External genitals

Testes Located in scrotum - lower temperature Covered by tunica albuginea, which divides testis into lobules containing seminiferous tubules Interstitial cells produce testosterone

Testes Spermatogenesis is process of sperm production Sperm precursor cells called spermatogonia Meiosis produces primary spermatocyte, which forms four spermatids with 23 chromosomes

Testes Spermatozoa - highly specialized cells Head contains genetic material Acrosome contains enzymes to assist sperm in penetration of ovum Mitochondria in midpiece provide energy for movement

Testes Production of testosterone by interstitial cells Testosterone “masculinizes” and promotes development of male accessory organs Promotes and maintains development of male accessory organs Stimulates protein anabolism and development of muscle strength

Quick Check What is the name of the male gonads? In what specific structures of the gonad are the sperm produced? What hormone is produced in the male gonad?

Male Reproductive Ducts Ducts through which sperm pass after exiting testes until they exit from the body Epididymis - single, coiled tube about 6 m in length; lies along the top and behind the testis in the scrotum Sperm mature and develop the capacity for motility as they pass through epididymis Ductus (vas) deferens - receives sperm from the epididymis and transports them from scrotal sac through the abdominal cavity Passes through inguinal canal Joins duct of seminal vesicle to form the ejaculatory duct

Male Accessory Sex Glands Accessory, or supportive, sex glands help produce semen: mixture of sperm and secretions of accessory sex glands Averages 3 to 5 mL per ejaculation Each milliliter containing about 100 million sperm

Male Accessory Sex Glands Seminal vesicles Pouchlike glands that produce about 60% of seminal fluid volume Secretion is yellowish, thick, and rich in fructose to provide energy needed by sperm for motility Less than 5% of seminal fluid volume

Male Accessory Sex Glands Prostate gland Shaped like a doughnut and located below bladder Urethra passes through the gland Secretion represents 30% of seminal fluid volume - is thin and milk-colored Activates sperm and is needed for ongoing sperm motility

Male Accessory Sex Glands Bulbourethral (Cowper’s) glands Resemble peas in size and shape Secrete mucus-like fluid constituting less than 5% of seminal fluid volume

Male External Genitals Penis and scrotum called genitalia Penis has three columns of erectile tissue: two dorsal columns called corpora cavernosa one ventral column surrounding urethra called corpus spongiosum Glans penis covered by foreskin (prepuce) Surgical removal of foreskin is called circumcision

Quick Check What duct leads from the epididymis? Which organs produce the fluid in semen? What is the function of erectile tissue?

Female Reproductive System Structural plan—organs classified as essential or accessory Essential organs are gonads (ovaries), which produce sex cells (ova) Accessory organs of reproduction Ducts or modified ducts Oviducts Uterus Vagina Sex glands - including the breasts External genitals

Ovaries Paired glands attached to ligaments in pelvic cavity on each side of uterus Microscopic structure Ovarian follicles - contain an oocyte, which is an immature sex cell (about 1 million at birth) About 350 to 500 mature follicles ovulate during the reproductive lifetime of most women - sometimes called graafian follicles Corpus luteum forms after ovulation

Ovaries Oogenesis - this meiotic cell division produces daughter cells with equal chromosome numbers (23) Production of estrogen and progesterone Granulosa cells surrounding the oocyte in the mature and growing follicles produce estrogen Estrogen causes development and maintenance of secondary sex characteristics Corpus luteum produces progesterone Progesterone stimulates secretory activity of uterine epithelium and assists estrogen in initiating menses

Quick Check What is the name of the female gonads? Where are the female gonads located? What is oogenesis? What hormones are produced by the female gonads?

Female Reproductive Ducts Uterine (fallopian) tubes (oviducts) Extend about 10 cm from uterus into abdominal cavity Expanded distal end surrounded by fimbriae Mucosal lining of tube is directly continuous with lining of abdominal cavity

Female Reproductive Ducts Uterus - composed of body, fundus, and cervix Lies in pelvic cavity just behind urinary bladder Myometrium is muscle layer Endometrium lost in menstruation Menopause - end of repetitive menstrual cycles (about 45–50 years of age)

Female Reproductive Ducts Vagina Distensible tube about 10 cm long Located between urinary bladder and rectum in the pelvis Receives penis during sexual intercourse and is birth canal for normal delivery of baby at end of term of pregnancy Accessory or supportive sex glands

Female Accessory Glands Bartholin’s (greater vestibular) glands Secrete mucus-like lubricating fluid Ducts open between labia minora

Female Accessory Glands Breasts Located over pectoral muscles of thorax Size determined by fat quantity more than amount of glandular (milk-secreting) tissue Lactiferous ducts drain at nipple, which is surrounded by pigmented areola Lymphatic drainage important in spread of cancer cells to other body areas

Quick Check What is another name for the uterine tubes? What three major functions does the uterus perform? What substance is conducted through lactiferous ducts?

Female External Genitals Vulva includes mons pubis, clitoris, orifice (meatus) of urethra, Bartholin’s gland, vagina, labia minora and majora, and hymen Perineum—area between vaginal opening and anus Surgical cut during childbirth called episiotomy

Menstrual Cycle Involves many changes in the uterus, ovaries, vagina, and breasts

Menstrual Cycle

Summary of Male and Female Reproductive Systems In men and women the organs of the reproductive system are adapted for the specific sequence of functions that permit development of sperm or ova after the successful fertilization and then the normal development and birth of offspring The male organs produce, store, and ultimately introduce mature sperm into the female reproductive tract

Summary of Male and Female Reproductive Systems The female system produces ova, receives the sperm, and permits fertilization followed by fetal development and birth, with lactation afterward Production of sex hormones is required for development of secondary sex characteristics and for normal reproductive functions in both sexes

Quick Check Which female structure is made of erectile tissue? What is another term for menses? Which hormone reaches a high peak just before ovulation?