Download - Figure 27.1
Copyright © 2010 Pearson Education, Inc. Figure 27.1
PeritoneumSeminalvesicle Ampulla ofductus deferensEjaculatoryduct
RectumProstateBulbourethralgland
AnusBulb of penis
Epididymis
UreterUrinary bladderProstaticurethra
Pubis
Membranousurethra Urogenitaldiaphragm
Corpuscavernosum Corpusspongiosum
Glans penisPrepuceExternalurethral orifice
Spongy urethra
TestisScrotum
Ductus (vas)deferens
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The Scrotum
• Temp kept constant by 2 muscles• Dartos wrinkles scrotal skin
• Cremaster elevate testes
Copyright © 2010 Pearson Education, Inc. Figure 27.2
Penis
Internal spermaticfascia
Superficial inguinalring (end of inguinal canal)
Urinary bladder
Spermatic cord Ductus (vas) deferensAutonomicnerve fibers
Testicular artery
Epididymis
Pampiniformvenous plexus
Tunica vaginalis(from peritoneum)Tunica albugineaof testis
Middle septumof scrotumCremaster muscleExternal spermaticfascia
Superficial fasciacontaining dartos muscleSkin
Scrotum
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The Testes
• Surrounded by:• Tunica vaginalis, from peritoneum
• Tunica albuginea, fibrous capsule
Copyright © 2010 Pearson Education, Inc. Figure 27.3a
Head of epididymis
Body of epididymis
Tail of epididymis
Efferent ductule
Rete testisStraight tubule
Duct of epididymis
Ductus (vas)deferens
Lobule
Testis
SeptumTunica albugineaTunica vaginalisCavity oftunica vaginalis
Spermatic cord
Seminiferoustubule
Blood vesselsand nerves
(a)
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The Testes
• Interstitial (Leydig) cells outside seminiferous tubules produce androgens
Copyright © 2010 Pearson Education, Inc. Figure 27.3c
Spermatogeniccells in tubuleepithelium
Interstitial cells
Areolarconnective tissue
SpermMyoidcells
(c)
Seminiferoustubule
Copyright © 2010 Pearson Education, Inc.
The Penis
• Penis consists of• Root and shaft ends in glans penis• Prepuce, or foreskin—the cuff of loose skin
covering the glans• Circumcision - surgical removal of foreskin • Crura
• Proximal end surrounded by ischiocavernosus muscle; anchors penis to pubic arch
Copyright © 2010 Pearson Education, Inc. Figure 27.4
Urinary bladder
Dorsal vesselsand nerves
Skin
Deep arteries (b)
(a)
Bulbourethral gland and ductUrogenital diaphragmBulb of penis
Corpora cavernosa
Corpus spongiosum
Section of (b)Spongy urethra
Glans penisPrepuce (foreskin)External urethral orifice
Corpora cavernosaUrethraTunica albuginea of erectile bodies
Corpus spongiosum
Crus of penisBulbourethral duct openingDuctus deferens
Ampulla of ductus deferens
Prostatic urethraOrifices of prostatic ducts
Prostate
Membranous urethra
Root of penis
Shaft (body) of penis
Ejaculatory ductSeminal vesicle
Epididymis
Testis
Ureter
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Accessory Glands: Seminal Vesicles
• Produces viscous alkaline seminal fluid • Fructose, ascorbic acid, coagulating enzyme
(vesiculase), and prostaglandins
• 70% of the volume of semen
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Accessory Glands: Prostate
• Encircles urethra inferior to bladder
• Secretes milky, slightly acid fluid:• Contains citrate, enzymes, and prostate-
specific antigen (PSA)
• Activation of sperm
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Accessory Glands: Bulbourethral Glands (Cowper’s Glands)• Pea-sized glands
• Prior to ejaculation, produce thick, clear mucus• Lubricates glans penis
• Neutralizes traces of acidic urine in urethra
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Semen
• Contains fructose, protects and activates sperm, and facilitates movement (relaxin)
• Prostaglandins• Decrease viscosity of mucus in cervix
• Stimulate reverse peristalsis in uterus
• 2–5 ml of semen ejaculated, containing 20–150 million sperm/ml
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Male Sexual Response
• Erection:• Parasympathetic reflex promotes release of
nitric oxide (NO)• NO causes erectile tissue to fill with blood• Expansion of corpora cavernosa
• Compresses drainage veins and maintains engorgement
• Corpus spongiosum keeps the urethra open
Copyright © 2010 Pearson Education, Inc. Figure 27.4
Urinary bladder
Dorsal vesselsand nerves
Skin
Deep arteries (b)
(a)
Bulbourethral gland and ductUrogenital diaphragmBulb of penis
Corpora cavernosa
Corpus spongiosum
Section of (b)Spongy urethra
Glans penisPrepuce (foreskin)External urethral orifice
Corpora cavernosaUrethraTunica albuginea of erectile bodies
Corpus spongiosum
Crus of penisBulbourethral duct openingDuctus deferens
Ampulla of ductus deferens
Prostatic urethraOrifices of prostatic ducts
Prostate
Membranous urethra
Root of penis
Shaft (body) of penis
Ejaculatory ductSeminal vesicle
Epididymis
Testis
Ureter
Copyright © 2010 Pearson Education, Inc.
Male Sexual Response
• Ejaculation• Sympathetic reflex
• Ducts and accessory glands contract and empty their contents
• Bladder sphincter muscle constrict,
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Meiosis
• Gamete formation involves meiosis• Nuclear division in 2n to n• Produces four daughter cells
• Introduces genetic variation
Copyright © 2010 Pearson Education, Inc. Figure 27.5 (1 of 2)
Mother cell(before chromosome replication)
Chromosomereplication
Chromosomereplication
2n = 4MITOSIS
ReplicatedchromosomeProphase
Chromosomesalign at themetaphase plate
Sister chromatids separate during anaphase
2n 2n
Metaphase
Daughtercells ofmitosis
Tetrad formed bysynapsis of replicated homologouschromosomes
Tetrads align at themetaphase plate
Homologous chromosomesseparate but sister
chromatids remain together during anaphase I
No further chromosomalreplication; sister chromatids
separate duringanaphase II
Daughter cells of meiosis II(usually gametes)
n n n n
Prophase I
Metaphase I
Daughter cellsof meiosis I
Meiosis II
MEIOSIS
Copyright © 2010 Pearson Education, Inc. Figure 27.5 (2 of 2)
MITOSIS MEIOSISOne, consisting of prophase, metaphase,anaphase, and telophase.
Number ofdivisions
Synapsis of homologouschromosomesDaughter cell number and genetic compositionRoles in the body
Two, each consisting of prophase, metaphase, anaphase, and telophase. DNA replication does not occur between the two nuclear divisions.
Does not occur. Occurs during mitosis I; tetrads formed, allowing crossovers.
Two. Each diploid (2n) cell is identical tothe mother cell.
Four. Each haploid (n) cell contains half as many chromosomes as the mother cell and is genetically different from the mother cell.
For development of multicellular adultfrom zygote. Produces cells for growthand tissue repair. Ensures constancy ofgenetic makeup of all body cells.
Produces cells for reproduction (gametes). Introduces genetic variability in the gametes and reduces chromosomal number by half so that when fertilization occurs, the normal diploid chromosomal number is restored (in humans, 2n = 46).
Copyright © 2010 Pearson Education, Inc. Figure 27.7a
Copyright © 2010 Pearson Education, Inc. Figure 27.7c
Basal lamina
Spermatogonium(stem cell)
Cytoplasm of adjacentsustentacular cells Sustentacular
cell nucleus
Tight junction betweensustentacular cells
Lumen ofseminifer-ous tubule
Late spermatids
Earlyspermatids
Secondaryspermatocytes
Cytoplasmicbridge
Primaryspermatocyte
Spermatozoa
Type B daughter cell
Type A daughter cellremains at basal laminaas a stem cell
(c) A portion of the seminiferous tublule wall, showing the spermato- genic cells surrounded by sustentacular cells (colored gold)
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Spermatogenesis
• Begins at puberty
Type A cells maintain germ cell line at basal laminaType B cells move toward lumen and develop
Copyright © 2010 Pearson Education, Inc. Figure 27.7b
Basal laminaSpermatogonium(stem cell)
Mitosis
Growth
Late spermatids
Early spermatids
Secondaryspermatocytes
Primaryspermatocyte
Spermatozoa
Type B daughter cell
Enters meiosis I and moves toadluminalcompartmentMeiosis IcompletedMeiosis II
Type A daughter cellremains at basal laminaas a stem cell
(b) Events of spermatogenesis, showing the relative position of various spermatogenic cells
Copyright © 2010 Pearson Education, Inc.
Sperm
• Major regions
1. Head: genetic region; nucleus and helmetlike acrosome containing hydrolytic enzymes that enable the sperm to penetrate an egg
2. Midpiece: metabolic region; mitochondria
3. Tail: locomotor region; flagellum
Copyright © 2010 Pearson Education, Inc. Figure 27.8a, b
CentriolesSpermatidnucleus
GolgiapparatusAcrosomal
vesicleMitochondria
Approximately 24 days
Excesscytoplasm
Nucleus
Acrosome
MicrotubulesFlagellum
Tail
Midpiece Head(a)
(b)
1 2
3
4
5
6 7
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Role of Sustentacular Cells
• Provide nutrients
• Dispose of excess cytoplasm during spermiogenesis
• Tight junctions form a blood-testis barrier • Prevents sperm antigens from escaping into
blood no immune system
• Sperm are not formed until puberty, they are absent during immune system development, and would not be recognized as “self”
Copyright © 2010 Pearson Education, Inc. Figure 27.7c
Basal lamina
Spermatogonium(stem cell)
Cytoplasm of adjacentsustentacular cells Sustentacular
cell nucleus
Tight junction betweensustentacular cells
Lumen ofseminifer-ous tubule
Late spermatids
Earlyspermatids
Secondaryspermatocytes
Cytoplasmicbridge
Primaryspermatocyte
Spermatozoa
Type B daughter cell
Type A daughter cellremains at basal laminaas a stem cell
(c) A portion of the seminiferous tublule wall, showing the spermato- genic cells surrounded by sustentacular cells (colored gold)