Chapter 28 Reproductive System Similarities between male and

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 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

Fig. 28. 2 Female anatomy • Uterus is thick-walled, muscular organ • Usually anteverted (pointed toward the front); may become retroverted in older women • Opening to uterus is the cervix Ureter Uterine (fallopian) tube Ovary Fimbriae of uterine tube Uterus Cervix of uterus Rectum Vagina Clitoris Ext. urethral orifice Vaginal orifice Labium minus Labium majus

Female anatomy • 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 Clitoris External urethral orifice Vaginal orifice Fig. 28. 2 Ureter Uterine (fallopian) tube Ovary Fimbriae of uterine tube Uterus Cervix of uterus Rectum Vagina

Fig. 28. 3 Ovarian artery Ovarian vein Suspensory ligament • 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 Infundibulum Fimbriae Ovary Uterine artery Uterine vein (a) Posterior view Ovarian ligament Uterine tube Uterus Broad ligament Ureter Cervix Vagina

Fig. 28. 4(a) Cross section of ovary Primary oocyte Follicle cells Primordial follicles LM 500 x • 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 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 follicle LM 500 x Primary oocyte Primary follicles Granulosa cells • primary oocyte surrounded by 1+ layer of granulosa cells • secretes estrogen as it matures • estrogen spurs changes in uterine lining

Fig. 28. 4 • 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 Corona radiata Primary oocyte Zona pellucida Antrum Secondary follicle LM 50 x Secondary follicle Zona pellucida Antrum Granulosa cells

Fig. 28. 4 • One or two secondary follicles develop into mature (vesicular) follicles Mature follicle Antrum Secondary oocyte • secondary oocyte has stopped in second half of meiosis Zona pellucida Corona radiata Zona pellucida • 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 Corona radiata Antrum Zona pellucida Secondary oocyte LM 100 x (e) Mature follicle

Fig. 28. 4 • Each month, one mature follicle ruptures and expels its oocyte Mature follicle Antrum Secondary oocyte • process called ovulation Zona pellucida Ovulated secondary oocyte Corona radiata Zona pellucida Antrum Secondary oocyte LM 100 x (e) Mature follicle

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 Developing corpus luteum Corpus luteum LM 25 x

Fig. 28. 4 • Meiosis completed only if fertilization occurs Corpus luteum • one egg and second polar body formed; polar body degenerates • If fertilization does occur, corpus luteum continues producing hormones until 3 months gestation Corpus albicans • embryo begins to produce own hormones LM 80 x (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 Corpus luteum Corpus albicans • If fertilization does occur LM 80 x (g) Corpus albicans

Meiosis in ovary development

Fig. 28. 6 Ovarian cycle Prim. Secondary follicle Days 1 3 5 7 Mature follicle 9 11 Follicular phase Ovulation 13 15 17 Corpus luteum forms 19 21 23 Corpus albicans 25 27 1 Luteal phase Ovulation Gonadotropin levels FSH LH Days 1 3 5 7 9 11 13 15 Ovulation 17 19 21 23

Fig. 28. 6 Ovarian hormone levels Estrogen Progesterone Days 1 3 5 7 9 11 13 15 17 19 21 23 25 27 1 Uterine cycle Menstrual flow Functional layer Basal layer Days 1 3 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

Fig. 28. 7 Uterine tube Ovarian artery Ovarian vein Suspensory ligament • AKA Fallopian tube, oviduct • Max. length 10 -12 cm by puberty • Infundibulum is funnel-shaped end, with fimbriae that enclose ovary Ovarian ligament Uterine tube Fimbriae Ovary • not actually attached to ovary Uterine artery Uterus Broad ligament 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

Fig. 28. 7 Uterine Tube Histology • 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 Muscularis Mucosa Lumen of uterine tube LM 35 x LM 400 x Uterine tube Simple ciliated columnar epithelium

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

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 Myometrium Wall of uterus Perimetrium Epithelium Lumen of uterus Functional layer Uterine glands Basal layer LM 45 x (c) Uterine wall Myometrium Endometrium

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 Endometrium Myometrium Wall of uterus Perimetrium Epithelium Lumen of uterus Functional layer Uterine glands Basal layer LM 45 x (c) Uterine wall Endometrium Myometrium

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

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

Fig. 28. 8 • Vagina is muscular tube ~10 cm 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

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

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

• 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 includes barrier, chemical, and surgical methods. (a) Condoms (b) Spermicidal foams (c) Diaphragm Each ductus deferens Uterine tubes are tied is 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 Glans Testis Scrotum

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

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

Fig. 28. 12 Structures within spermatic cord Ductus (vas) deferens Pampiniform plexus Testicular artery Testicular nerve Epididymis Testis • 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

Within each testis: 1. Spermatogonium produces primary spermatocyte Fig. 28. 14 Interstitial space Interstitial cells Sustentacular cell Spermatogonium 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 46 1 Mitotic division 46 Primary spermatocyte Meiosis I 46 2 Secondary spermatocyte 23 Wall of seminiferous tubule 23 3 Spermatid 23 23 23 Meiosis II 23 23 23 4 23 Spermatids becoming sperm 23

Fig. 28. 14 Development of spermatids Developing acrosome cap Spermatid nucleus Mitochondria Developing flagellum Acrosome cap Excess cytoplasm Developing acrosome cap Acrosome cap Spermatid nucleus Nucleus Mitochondria

Fig. 28. 14 • Spermatids develop into mature sperm (AKA spermatozoa) • Acrosome cap contains digestive enzymes Acrosome cap Nucleus Mitochondria Head Midpiece • help penetrate secondary oocyte for fertilization Tail (flagellum) • Tail is made of microtubules • Mitochondria in midpiece provide energy to move tail Sperm (b) Spermiogenesis

Fig. 28. 13 Ductus deferens • Sperm leave seminiferous tubule not yet mature • Sperm mature in epididymis Head of epididymis Duct of epididymis Seminiferous tubule Efferent ductule Septum Lobule Body of epididymis Tail of epididymis • structure wraps around testis • head on superior surface, tale inferior • duct of epididymis 4 -5 m long

Fig. 28. 15 Section of duct of epididymis Sperm in lumen of duct of epididymis LM 50 x (c) Epididymis • Cross-section of epididymis shows many ducts filled with sperm • If not ejaculated, sperm resorbed by lining of duct of epididymis

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

Ureter • Seminal vesicles secrete viscous, whitish fluid containing Urinary bladder Seminal vesicle Ejaculatory duct Prostate gland Prostatic urethra Bulbourethral gland Bulb Crus Urogenital diaphragm Corpus cavernosum • Ductus (vas) deferens Epididymis Testis Penis Corpus spongiosum Spongy urethra Glans • 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)

Ureter • Prostate gland produces mucin, secretes milky fluid with Urinary bladder Seminal vesicle Ejaculatory duct Prostate gland Prostatic urethra Bulbourethral gland Bulb Crus Urogenital diaphragm Ductus (vas) deferens Corpus cavernosum • 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 Epididymis Testis Penis Corpus spongiosum Spongy urethra Glans

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

Fig. 28. 15 Ureter • Semen contains sperm and products of seminal vesicles, prostate gland, bulbourethral glands • When released during intercourse called ejaculate Urinary bladder Seminal vesicle Ejaculatory duct Prostate gland Prostatic urethra Bulbourethral gland Bulb Crus Urogenital diaphragm Ductus (vas) deferens Corpus cavernosum Epididymis Testis Penis Corpus spongiosum Glans • 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

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 Bulb of penis Pubic symphysis Right crus of penis Body of penis Root of penis Corpora cavernosa Corpus spongiosum Scrotum (a) Anterolateral view Glans 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 = 13 cm (~5 in. ) • Avg. circumference 11. 7 cm Membranous urethra Bulb of penis Pubic symphysis Right crus of penis Body of penis Root of penis Corpora cavernosa Corpus spongiosum Scrotum (a) Anterolateral view Glans External urethral orifice

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

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 Dorsal vein Dorsal artery Dorsal nerve Deep dorsal vein Tunica albuginea Central artery Corpus cavernosum Venous spaces Deep fascia Corpus spongiosum Superficial fascia Skin Spongy urethra Penis Cross section

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 Dorsal vein Dorsal artery Dorsal nerve Deep dorsal vein Tunica albuginea Central artery Corpus cavernosum Venous spaces Deep fascia Corpus spongiosum Superficial fascia Skin Spongy urethra Penis Cross section

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