Chapter 28 Reproductive System

Similarities between male and female systems Gonads are primary sex organs ovaries; testes Gonads produce haploid sex cells called gametes haploid = half the number of chromosomes of the parent cells gametes produced by meiosis ovaries produce oocytes (eggs) testes produce sperm Gonads produce large amounts of sex hormones estrogen and progesterone are most important in females androgens (including testosterone) are most important in males

Similarities between male and female systems Reproductive systems are dormant until puberty Accessory organs carry gametes from gonads to site of fertilization Fertilization = fusion of sperm and egg into zygote

Female anatomy Ovaries are almond-size Ureter Uterine (fallopian) tube Ovary Fimbriae of uterine tube Uterus Ovaries are almond-size Connected to uterus by fallopian (uterine) tubes Fimbraiae are finger-like projections from fallopian tube and catch released eggs

Female anatomy Fig. 28.2 Uterus is thick-walled, muscular organ Ureter Uterine (fallopian) tube Uterus is thick-walled, muscular organ Usually anteverted (pointed toward the front); may become retroverted in older women Opening to uterus is the cervix Ovary Fimbriae of uterine tube Uterus Cervix of uterus Rectum Vagina Clitoris Ext. urethral orifice Vaginal orifice Labium minus Labium majus

Female anatomy Fig. 28.2 Ureter Uterine (fallopian) tube Vagina is thick-walled, fibromuscular tube that connects orifice to uterus Folds of skin outside vagina are labia minora and labia majora Clitoris is highly sensitive, erectile bulb of skin homologous to penis Ovary Fimbriae of uterine tube Uterus Cervix of uterus Rectum Vagina Clitoris External urethral orifice Vaginal orifice

Broad ligament is a drape of peritoneum over uterus Fig. 28.3 (a) Posterior view Ovarian artery Ovarian vein Broad ligament is a drape of peritoneum over uterus Ovaries held in place by ovarian ligaments and suspensory ligaments suspensory ligament contains ovarian artery and vein Ovarian artery and ovarian vein supply each artery branch off aorta Suspensory ligament Ovarian ligament Uterine tube Infundibulum Fimbriae Ovary Uterus Broad ligament Uterine artery Uterine vein Ureter Cervix Vagina

Fig. 28.4(a) Cross section of ovary Ovarian follicles contain an oocyte and follicle cells Before birth, all oocytes develop and start meiosis, pause in Prophase I of meiosis called primordial follicles each has 23 pairs of chromosomes at birth 1.5 million primordial follicles Primary oocyte Follicle cells Primordial follicles LM 500x Medulla Primordial follicles Cortex

Fig. 28.4 Primary oocyte Granulosa cells Beginning at puberty, each month, about 20 primordial follicles mature into primary follicles primary oocyte surrounded by 1+ layer of granulosa cells secretes estrogen as it matures estrogen spurs changes in uterine lining Primary follicle LM 500x Granulosa cells Primary oocyte Primary follicles

Each primary follicle develops into a secondary follicle Corona radiata Fig. 28.4 Primary oocyte Zona pellucida Each primary follicle develops into a secondary follicle contains primary oocyte many layers of granulosa cells fluid-filled space called antrum zona pellucida and corona radiata are protective layers Antrum Secondary follicle Granulosa cells LM 50x Secondary follicle Zona pellucida Antrum

Zona pellucida Secondary oocyte Antrum Mature follicle LM 100x (e) Mature follicle Secondary oocyte Corona radiata Fig. 28.4 One or two secondary follicles develop into mature (vesicular) follicles secondary oocyte has stopped in second half of meiosis two cells produced, each has 23 chromosomes (1 of each) one cell will become egg, one is polar body, degenerates many layers of granulosa cells large antrum; still has zona pellucida and corona radiata

Each month, one mature follicle ruptures and expels its oocyte Zona pellucida Secondary oocyte Antrum Mature follicle LM 100x (e) Mature follicle Secondary oocyte Corona radiata Ovulated secondary oocyte Fig. 28.4 Each month, one mature follicle ruptures and expels its oocyte process called ovulation

Fig. 28.4 After ovulation, some of follicle stays in ovary, becomes corpus luteum secretes sex hormones progesterone and estrogen stimulate continued buildup of uterine lining prepare uterus for implantation of zygote Corpus luteum Corpus luteum Developing corpus luteum LM 25x

Meiosis completed only if fertilization occurs LM 80x Corpus albicans (g) Corpus albicans Fig. 28.4 Meiosis completed only if fertilization occurs one egg and second polar body formed; polar body degenerates If fertilization does occur, corpus luteum continues producing hormones until 3 months gestation embryo begins to produce own hormones Corpus luteum

If fertilization does occur LM 80x Corpus albicans (g) Corpus albicans Fig. 28.4 If fertilization does not occur, corpus luteum degenerates into corpus albicans, usually completely resorbed by ovary production of hormones decreases, menstruation occurs as uterine lining is shed If fertilization does occur Corpus luteum

Meiosis in ovary development

Fig. 28.6 Ovulation Ovarian cycle Follicular phase LH FSH Prim. follicle Secondary Mature Corpus luteum forms Corpus albicans 9 7 5 3 1 11 13 15 17 19 21 23 25 27 Gonadotropin levels Days Luteal phase Fig. 28.6

Fig. 28.6 Ovarian hormone levels Estrogen Progesterone Days 1 3 5 7 9 13 15 17 19 21 23 25 27 1 Uterine cycle Menstrual flow Functional layer Basal layer Days 1 3 5 7 9 1 1 13 15 17 19 21 23 25 27 1 Menstrual phase Proliferative phase Secretory phase

First menstrual cycle = menarche End of menstrual cycles = menopause, no menstrual period for one year (not pregnant) Usually age 45-55 Perimenopause is time before menopause begins estrogen levels begin to drop irregular or skipped periods

Uterine tube AKA Fallopian tube, oviduct Ovarian artery Fig. 28.7 Ovarian vein Ovarian ligament Suspensory ligament AKA Fallopian tube, oviduct Max. length 10-12 cm by puberty Infundibulum is funnel-shaped end, with fimbriae that enclose ovary not actually attached to ovary Uterine tube Fimbriae Ovary Uterus Broad ligament Uterine artery Uterine vein Ureter Cervix Vagina

Ectopic pregnancy Zygote implants in fallopian tube instead of uterus Tube unable to expand to accommodate growing embryo develops for up to 8 weeks Symptoms: severe cramping Tube may burst if embryo not removed

Uterine Tube Histology Muscularis Fig. 28.7 Lumen of uterine tube Mucosa Mucosa is ciliated columnar epithelium and areolar connective tissue folds in lumen reduce diameter beating of cilia draws egg into tube and carries it toward uterus peristalsis of muscularis also carries egg forward LM 35x LM 400x Uterine tube Simple ciliated columnar epithelium

Cervix is narrow portion of uterus that projects into vagina Fig. 28.7 (a) Posterior view Cervix is narrow portion of uterus that projects into vagina Mucin-secreting glands in cervix create mucus plug probably barrier to prevent pathogens from entering uterus plug thins during ovulation to allow sperm entry into uterus NOT thick enough to prevent sperm passage during rest of cycle Cervix

Wall of uterus has 3 tunics Endometrium Perimetrium (c) Uterine wall LM 45x Myometrium Lumen of uterus Epithelium Uterine glands Basal layer Functional Wall of uterus Fig. 28.7 Wall of uterus has 3 tunics Perimetrium is serosa, continuous with broad ligament Myometrium is muscular layer 3 intertwining layers of muscle thickens during pregnancy

Endometrium is innermost layer, mucosa Perimetrium (c) Uterine wall LM 45x Myometrium Lumen of uterus Epithelium Uterine glands Basal layer Functional Wall of uterus Fig. 28.7 Endometrium is innermost layer, mucosa divided into 2 layers functional layer is superficial, shed during menstruation basal layer is permanent, doesn’t change much during uterine cycle

Cervical cancer detected through Pap smear Speculum inserted in vagina, scraping of cells taken from cervix

Normal epithelial cells Page 852 Normal epithelial cells Dysplastic cells LM 140x LM 160x Normal Pap smear. Abnormal Pap smear. Cells from cervix examined under microscope for abnormal cells, called dysplastic cells May be sign of cervical cancer

Vagina is muscular tube ~10cm long Fig. 28.8 Vagina is muscular tube ~10cm long Wall is relatively thin, distensible Functions as birth canal Lots of blood and lymph vessels Rugae present, especially in inferior region Formed from mucosal tissue

Vaginal orifice is opening to vagina Mucosal tissue projects into vaginal opening to create hymen Sometimes broken during first sexual intercourse May be broken by masturbation, tampon use, certain activities (horseback riding, etc.) Shape, thickness of hymen may differ dramatically

External genitalia = vulva Pubic symphysis External genitalia = vulva includes labia majora and minora, clitoris, vestibule vestibule is opening between labia minora Mons pubis is skin and connective tissue anterior to pubic symphysis covered with pubic hair after puberty Mons pubis Labium minor Labium major

Labia majora are outer folds of skin Pubic symphysis Labia majora are outer folds of skin have pubic hair Labia minora are inner folds of skin highly vascularized, have sebaceous glands; release mucin that acts as lubricant during sexual intercourse Mons pubis Labium minor Labium major

Glans is layer of skin over clitoris highly sensitive Prepuce is an external fold of labia minora forms hood over clitoris Prepuce Clitoris

Male hyena Female hyena

Female hyena’s clitoris is extended, looks like penis Labia are fused, look like scrotum Vaginal orifice is at tip of clitoris

Contraception Contraception includes barrier, chemical, and surgical methods. (a) Condoms (b) Spermicidal foams (c) Diaphragm Each ductus deferens is tied off and cut Uterine tubes are tied off and cut (d) Oral contraceptive (e) Intrauterine device (IUD) (f) Tubal ligation (g) Vasectomy

Male anatomy Fig. 28.11 Ureters Urinary bladder Ampulla of ductus deferens Pubic symphysis Seminal vesicle Ductus (vas) deferens Ejaculatory duct Urogenital diaphragm Prostate gland Bulbourethral gland Urethra Anus Penis Epididymis Testis Glans Scrotum

Male anatomy Testes (sing. testis) are primary male sex organ Urinary bladder Male anatomy Pubic symphysis Ductus (vas) deferens Testes (sing. testis) are primary male sex organ produce sperm and hormones held inside skin sac called scrotum Urethra Penis Epididymis Testis Glans Scrotum

Scrotum holds testes away from body Fig. 28.12 Scrotum holds testes away from body ideal temperature for sperm is 3°C below body temp homologous with female labia majora ridge at center is raphe wall of scrotum has 3 layers skin superficial fascia dartos muscle and cremaster muscle relax at high temps, contract at low temps to maintain testes at proper temp. Cremaster muscle Internal spermatic fascia Dartos muscle Raphe Scrotum

Blood vessels and nerves to testes travel through spermatic cord Fig. 28.12 Blood vessels and nerves to testes travel through spermatic cord originates near inguinal ligament veins form pampiniform plexus that surrounds testicular artery cools blood traveling to testis Vas deferens (ductus deferens) carries sperm Ductus (vas) deferens Pampiniform plexus Structures within spermatic cord Testicular artery Testicular nerve Epididymis Testis

Spermatogonium produces primary spermatocyte Fig. 28.14 Within each testis: Spermatogonium produces primary spermatocyte 2. Primary spermatocyte undergoes meiosis I, becomes haploid secondary spermatocyte 3. Secondary spermatocyte undergoes meiosis II, produces 2 haploid spermatids 4. Morphological changes produce sperm Interstitial cells Interstitial space Sustentacular cell Spermatogonium 46 1 Mitotic division 46 Primary spermatocyte 46 2 Meiosis I Secondary spermatocyte 23 23 Wall of seminiferous tubule 3 Meiosis II 23 23 23 23 Spermatid 4 23 23 23 23 Spermatids becoming sperm

Fig. 28.14 Development of spermatids Developing acrosome cap Mitochondria Spermatid nucleus Acrosome cap Nucleus Mitochondria Excess cytoplasm Developing acrosome cap Spermatid nucleus Developing flagellum Acrosome cap Spermatid nucleus

Spermatids develop into mature sperm (AKA spermatozoa) Mitochondria Nucleus Acrosome cap (b) Spermiogenesis Sperm Tail (flagellum) Midpiece Head Fig. 28.14 Spermatids develop into mature sperm (AKA spermatozoa) Acrosome cap contains digestive enzymes help penetrate secondary oocyte for fertilization Tail is made of microtubules Mitochondria in midpiece provide energy to move tail

Sperm leave seminiferous tubule not yet mature Fig. 28.13 Sperm leave seminiferous tubule not yet mature Sperm mature in epididymis structure wraps around testis head on superior surface, tale inferior duct of epididymis 4-5m long Head of epididymis Duct of epididymis Ductus deferens Seminiferous tubule Efferent ductule Septum Lobule Body of epididymis Tail of epididymis

Cross-section of epididymis shows many ducts filled with sperm Fig. 28.15 Cross-section of epididymis shows many ducts filled with sperm If not ejaculated, sperm resorbed by lining of duct of epididymis Section of duct of epididymis Sperm in lumen of duct of epididymis LM 50x (c) Epididymis

Sperm leave epididymis, travel to vas deferens (ductus deferens) Urinary bladder Pubic symphysis Sperm leave epididymis, travel to vas deferens (ductus deferens) travel through spermatic cord Sperm moved by sterocilia sperm do not swim prior to ejaculation Ductus (vas) deferens Urethra Penis Epididymis Testis Glans Scrotum

Seminal vesicles secrete viscous, whitish fluid containing Ureter Seminal vesicles secrete viscous, whitish fluid containing fructose to nourish sperm prostaglandins to promote widening of cervix bicarbonate to buffer acidic environment of vagina Seminal vesicles merge with vas deferens to create ejaculatory duct (meets with prostatic urethra) Urinary bladder Seminal vesicle Ejaculatory duct Prostate gland Prostatic urethra Bulbourethral gland Bulb Urogenital diaphragm Crus Ductus (vas) deferens Corpus cavernosum Epididymis Testis Penis Corpus spongiosum Spongy urethra Glans

Prostate gland produces mucin, secretes milky fluid with Ureter Prostate gland produces mucin, secretes milky fluid with citric acid to nourish sperm seminalplasmin, an antibiotic to combat UTIs prostate-specific antigen (PSA) helps liquify semen following ejaculation Vas deferens merges into urethra within prostate Urinary bladder Seminal vesicle Ejaculatory duct Prostate gland Prostatic urethra Bulbourethral gland Bulb Urogenital diaphragm Crus Ductus (vas) deferens Corpus cavernosum Epididymis Testis Penis Corpus spongiosum Spongy urethra Glans

Ureter Bulbourethral glands are located within urogenital diaphragm (muscle layer) Produce clear, viscous mucus that lubricates and buffers urethra prior to ejaculation Urinary bladder Seminal vesicle Ejaculatory duct Prostate gland Prostatic urethra Bulbourethral gland Bulb Urogenital diaphragm Crus Ductus (vas) deferens Corpus cavernosum Epididymis Testis Penis Corpus spongiosum Spongy urethra Glans

When released during intercourse called ejaculate Fig. 28.15 Ureter Semen contains sperm and products of seminal vesicles, prostate gland, bulbourethral glands When released during intercourse called ejaculate usually 3-5 ml 200-500 million sperm per ejaculation 2 weeks from seminiferous tubules to ejaculate Sperm number may decrease with sexual activity, volume of ejaculate won’t Urinary bladder Seminal vesicle Ejaculatory duct Prostate gland Prostatic urethra Bulbourethral gland Bulb Urogenital diaphragm Crus Ductus (vas) deferens Corpus cavernosum Epididymis Testis Penis Corpus spongiosum Glans

Male external genitalia include penis and scrotum Fig. 28.17 Male external genitalia include penis and scrotum Root of penis is internal to body surface Bulb of penis attaches to bulbospongiosus muscle Crus of penis attach to pubic arch Body or shaft of penis is elongated and movable Membranous urethra Pubic symphysis Bulb of penis Right crus of penis Body of penis Root of penis Root of penis Corpora cavernosa Corpus spongiosum Glans Scrotum External urethral orifice (a) Anterolateral view

Glans is tip of penis, contains external urethral orifice Fig. 28.17 Glans is tip of penis, contains external urethral orifice Prepuce is layer of skin that covers glans removed in circumcision Average length, pubic symphysis to tip of glans = 13cm (~5 in.) Avg. circumference 11.7 cm Membranous urethra Pubic symphysis Bulb of penis Right crus of penis Body of penis Root of penis Root of penis Corpora cavernosa Corpus spongiosum Glans Scrotum External urethral orifice (a) Anterolateral view

Prepuce is layer of skin that covers glans Page 868 (a) Circumcised penis (b) Uncircumcised penis Prepuce Prepuce is layer of skin that covers glans pulls back when penis is erect removed in circumcision

3 erectile bodies within penis Penis Cross section Corpus cavernosum Deep dorsal vein spongiosum Skin Spongy urethra Superficial fascia Deep fascia Venous spaces Central artery Tunica albuginea Dorsal nerve Dorsal vein Dorsal artery Fig. 28.17 3 erectile bodies within penis Corpora cavernosa (pl.) terminates in shaft of penis Corpus spongiosum continues to tip of glans contains spongy urethra

Erectile bodies have venous spaces surrounding central artery Penis Cross section Corpus cavernosum Deep dorsal vein spongiosum Skin Spongy urethra Superficial fascia Deep fascia Venous spaces Central artery Tunica albuginea Dorsal nerve Dorsal vein Dorsal artery Fig. 28.17 Erectile bodies have venous spaces surrounding central artery Sexual excitement causes blood to flow into central artery and venous spaces Erectile bodies compress veins, blood cannot flow out, causes erection

Aging and Reproductive systems “Male menopause” = male climacteric slight decrease in size of testes decreased testosterone levels Prostate enlargement may cause erectile dysfunction (inability to achieve erection) or impotence (inability to maintain erection) urethra passes through prostate, so enlargement of prostate prevents normal fluid flow through urethra Risk factors: age, heart disease, diabetes, smoking, prostate surgery