Reproductive System
Chapter 27
MALE REPRODUCTIVE SYSTEM
Male Reproductive Anatomy Overview
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Testes in scrotum
Epididymis
Vas deferens
Ejaculatory duct
Urethra (3 parts)
Seminal vesicles
Prostate
Bulbourethral glands
http://www.everydayhealth.com/mens-health-pictures/male-anatomy-and-thereproductive-system.aspx , with illustrations by Catherine Delphia
Anatomical Structures
• Scrotum (5)
– Superficial sac for testes = 3° lower than core
• Requirement w/ sperm production
– Muscles facilitate
• Dartos: smooth muscle wrinkles for insulation
• Cremaster: ontracts w/ cold = pulled closer; hot = opposite
• Testes (1)
– Two tunics
• Tunica vaginalis: outer from peritoneum
• Tunica albuginea: inner fibrous layer that divides into lobules
– Seminiferous tubules where spermatogenesis occurs
• Surrounded by testosterone producing interstitial cell
• Converge at rete testes before epididymis
– Testicular cancer: most common in young; regular self-exam
increases early detection
Anatomical Structures (cont.)
• Penis (2)
– Root w/ free shaft ending in glans penis
• Foreskin (prepuce) covers; removed w/ circumcisition
– 3 regions of erectile tissue
• Corpus spongiosum (1) surrounds urethra; forms glans
• Corpora cavernosa (2)
• Epididymis (3)
– Stores non-motile sperm till maturation
• ~ 20 days  swimmers
• Released w/ejaculation
– Stereocilia absorbs excess fluids and supplies nutrients
Anatomical Structures (cont.)
• Vas deferens
– W/ blood, nerves, and lymph to testes = spermatic
cord
– Peristalsis propels sperm
– Joins seminal vesicle  ejaculatory duct (4)
– Vasectomy: male sterilization technique: ~ 50%
reversal success
• Urethra
– Urinary and reproductive function
– 3 parts (prostatic, membranous, and spongy)
Anatomical Structures (cont.)
• Seminal vesicles
– ~60% semen
– Viscous, alkaline solution, w/fructose (ATP) and prostaglandins (down cervical
mucus viscocity)
• Prostate
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~33% semen
Milky, acidic solution w/ citrate, enzymes, and specific antigens
Hypertrophy: difficulty urinating or having an erection
Prostatis: inflammation
• Bulbourethral gland
– < 5%
– Thick, alkaline mucus to neutralize traces of urine & lubricate
• Semen
• Alkalinity ~ 7.3 – 7.7
– Neutralizes vagina
– Survival < 48 hrs after ejaculation
– Sterility: reduced production of sperm
Male Sexual Response: Erection
• PNS releases NO = penis engorges w/ blood
– Relaxes penile tissue
– Vasodilate vascular supply
• Corpora cavernosa compresses vein drainage
to maintain
• Corpus spongiosum maintains urethral
opening during ejaculation
• PNS signals bulbourethral secretions to
lubricate glans
Male Sexual Response: Ejaculation
• Spinal reflex of SNS triggers
• Climax/ orgasm
– Bladder sphincter constricts  urine retention
– Contraction of ducts and accessory glands
– Penile muscles rapidly contract to propel
• Resolution follows
– Muscular and physiological relaxation
– Latent period prevents consecutive erection
• Erectile dysfunction: inability to attain an
erection
Gametogenesis
• Nuclear division reduces chromosome number
to produce gametes
– Humans w/ 23 pairs (46) homologous
chromosomes
– Gametes w/23 chromosomes = haploid (n)
– Gamete + gamete = fertilization = diploid (2n)
– Occurs in gonads (testes and ovaries)
• 1 parent cell produces ‘4’ daughter cells
Meiosis
• Phases mirror mitosis (pro-, meta-, ana-, telophase)
• Replication of DNA prior to
• Meiosis I
– Homologs synapse and crossing over occurs at chiasma
(prophase I)
– 1 cell  2 cells w/ ½ DNA amount
• Meiosis II
– Chromatids separate
– Resembles mitosis
• Introduces genetic variability
• Nondisjunction w/ failure to separate in anaphase I or II
– Chromosomal number abnormalities
Spermatogenesis
• Formation of sperm
– ~ age 14 to death
– ~400 million a day
• Spermatogonium (stem) divides into multiple
primary spermatocytes (mitosis)
• Primary to secondary spermatocytes (meiosis I)
• Secondary to spermatids (meiosis II)
Spermiogenesis: Spermatids to sperm (fig 27.8)
– Circular cell to 3 distinct regions
• Head w/ acrosome (genetic), midpiece (metabolic), tail
(locomotor)
Spermatogenesis (cont.)
Hormonal Regulation
• Hypothalamus: GnRH  AP: FSH/LH  testes (review)
– FSH: indirect spermatogensis stimuli by maintaining high
[testosterone]
– LH: prods seminiferous tubules to produce testosterone
• Spermatogenesis push
• High [testosterone] effects other targets
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Maturation of sex organs
Development/ maintenance of 2° sex characteristics
Stimulates sex drive
Inhibits GnRH
• Inhibin up w/ increase [sperm]  inhibits FSH/LH
release
FEMALE REPRODUCTIVE SYSTEM
Female Reproductive Anatomy Overview
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Ovaries
Uterine tubes
Uterus
Vagina
External
genitalia
• Mammary
glands
http://www.drmalpani.com/book/chapter2a.html
Anatomical Structures
• Ovaries
– Held in place by ligaments (ovarian, broad, and
mesovarium)
– Two tunics
• Germinal epithelium: cuboidal cells of peritoneum
• Tunica albuginea: inner fibrous layer
– Contain sac-like follicles w/ oocytes
• Uterine tubes (Oviducts)
– Fimbriae ‘sweep’ ovulated 2° oocyte into
infundibulum to ampulla for fertilization
– Ectopic pregnancy: fertilization outside uterine tube
– Pelvic inflammatory disease: bacterial infection
Anatomical Structures (cont.)
• Uterus
– 3 walled organ (peri-, myo-, and endometrium)
– 3 regions (fundus, body, cervix)
• Isthmus, cervical canal, external and internal os
– Endometrial layers
• Stratum functionalis: cylic changes w/ ovarian hormones; sloughed ~ every
28days
• Stratum basalis: forms new functionalis; unresponsive to ovarian hormones
– Cervical cancer
– Prolapse: uterus sinks to external vagina from muscle weakening
• Vagina
– 3 layers (fibroelastic adventitia, smooth muscularis, strat. squam.
mucosa w/ rugae)
– Passageway for birthing and menses
– Acidic environment impairs sperm mobility and resist bacteria
Anatomical Structures (cont.)
• External Genitalia
– Mons pubis
– Labia majora and minora
– Clitoris
• Glans and prepuce
• Corpora cavernosa only
– Vestibule
• Vestibular glands lubricate and moisten
• Mammary glands
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Present in males & females, but fxn in females only
Stimulated by PRL and oxytocin
Areola w/sebaceous glands (minimize chapping) and nipple
Suspensory ligaments naturally support
Milk in lobules from alveoli cells to lactiferous duct and collects in
lactiferous sinus in nipple w/ nursing
Oogenesis
• Formation of ova (egg)
– Fetus to birth and puberty to menopause
– 7 million to 2 million and 250, 000 to < 500
• Oogonia (stem) divide into multiple primary oocytes in
primordial follicles (mitosis)
• Primary start meiosis, but stall at prophase I (birth)
• LH surge activates multiple, but only 1 finish meiosis I
– First polar body
– Secondary oocyte stalls at metaphase II before ovulation
• Fertilization completes meiosis II
– One ovum (functional)
– Second polar body
Oogenesis (cont.)
Comparing Gametogenesis
Oogenesis
• Mitotic division completed
at birth
Spermatogenesis
• Mitotic division puberty to
death
• 1 functional ova and 3 polar
bodies (degenerate)
• 4 functional sperm
• 1 ova per cycle (~ 28 days)
• Continuous production
Ovarian Cycle
• Maturation of ova events
– Typically 28 days
– 21 – 40 more common
• Follicular phase (variable)
– Follicle grows
– Day 1 to 14
• Luteal phase (constant)
– Corpus luteum activity
– Day 14 -28
• Ovulation is midcycle
Follicular Phase
• Primordial to primary follicle
– Outer sim. squa  outer sim. cub.
• Primary to secondary follicle
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Sim. cub  strat. squam (granulosa cells)
Granulosa and thecal cells secrete estrogen
Zona pellucida encapsulates oocyte
Antrum forms
• Secondary to vesicular follicle
– Growing antrum isolates granulosa  corona radiata
– Bulges at surface for ovulation
• Fraternal vs. identical twins
– Meiosis I completed
• Fig 27.18
Luteal Phase
• Corpus luteum formed after ovulation
– Antrum w/ blood
– Granulosa cells increase size
– Progesterone (some estrogen) secretion starts
• ~ 10 days till degeneration
– Scar, corpus albicans, results
– Pregnancy prevents
• Hormone secretion as bridge w/ placenta (~3 months)
Ovarian Cycle Hormonal Control
• GnRH  LH and FSH  estrogen and progesterone
– Estrogen inhibits GnRH (childhood)
– Hypothalamus less responsive approaching puberty
– Adult pattern reached = menarche
• Day 1: GnRH stimulates LH and FSH release
– Stimulate follicle growth, development, and estrogen release
– Rising estrogen
• Inhibits LH and FSH release
• High levels produce LH surge  primary to secondary oocyte
• Day 14: LH surge triggers ovulation
– Corpus luteum formation (estrogen, progesterone, and inhibin)
– Inhibit LH and FSH
• Days 26 – 28: ovarian hormones drop
– LH and FSH NOT inhibited
– Cycle repeats
• Fig 27.19
Uterine Cycle
• Cyclical changing of endometrium
– FH and FSH govern
– Linked w/ ovarian cycle
• Days 1 – 5
– Menses, ‘sloughing off’ of endometrium
– Ovarian hormones low; LH and FSH rising
• Days 6 - 14
– Proliferative phase rebuilds endometrium
– Estrogen increases  cervical mucus thins
• Days 15 -28
– Secretory phase preps uterus for embryo
– Progesterone increase creates cervical plug from cervical mucus
Ovarian and Uterine Cycles
http://www.theholisticcare.com/cure%20diseases/Menstruation.htm