Chapter 26b

Reproduction and Development

Male Reproductive Structures

• External genitalia• Penis and scrotum

• Common passageway• Urethra

• Accessory glands and ducts• Prostate gland• Seminal vesicle• Bulbourethral gland

Figure 26-8 (1 of 2)

Male Reproductive Structures - Overview

Figure 26-8 (2 of 2)

Male Reproductive Structures - Erectile Tissues

Male Reproductive Structures

• Testes (sperm production)• Seminiferous tubules

• Epididymis (sperm maturation)• Vas deferens (aka “ductus deferens”, a

passageway into abdomen and delivery to the urethra)

Figure 26-9a

Male Reproductive Structures - Sagittal View

Urethra

ScrotumTestis

Rectum

UreterUrinarybladder

Prostategland

Ejaculatoryduct

Bulbourethralgland

Vas deferens

Pubicsymphysis

Epididymis

Seminalvesicle

Penis

(a)

ANATOMY SUMMARYTHE MALE REPRODUCTIVE SYSTEM

Figure 26-9b

Male Reproductive Structures - Scrotal Structures

Head ofepididymis

Seminiferoustubule

Vas deferens

Epididymis

Scrotal cavity(b)

ANATOMY SUMMARY

THE MALE REPRODUCTIVE SYSTEM

Figure 26-9c

Seminiferous Tubule - Cross-Section

Spermatogonium

Capillary

Leydig cell

(c)

Sertoli cell

ANATOMY SUMMARY

THE MALE REPRODUCTIVE SYSTEM

Spermatogenesis in the Testes

• Seminiferous tubules• Sertoli cells surround and support developing

sperm• Spermatogonia divide and produce all sperm

cells• Primary and secondary spermatocytes• Spermatids• Spermatozoa

• Interstitial tissues support spermatogenesis• Leydig cells testosterone• Capillaries deliver nutrients and remove wastes

Figure 26-9d

Seminiferous Tubule - Detail

Sertoli cells

SpermatozoaSpermatidsSecondary spermatocyte

Primary spermatocyteSpermatogonium

Leydigcells

CapillaryFibroblast

Basallamina

Lumen ofseminiferous tubule

(d)

Tight junctionbetween Sertoli cells

ANATOMY SUMMARY

THE MALE REPRODUCTIVE SYSTEM

Figure 26-10

Spermatozoa Structure

Tail(flagellum)

Mid piece

Head

Microtubules

Mitochondrialspiral

Centrioles

Nucleus

Acrosomecontainsenzymes

Regulation of Spermatogenesis

• Hormones control the production of sperm• GnRH stimulates the release of LH and FSH• LH Leydig cells testosterone • FSH Sertoli cells cell products

Figure 26-11

Regulation of Spermatogenesis

LH

GnRHHypothalamus

Anteriorpituitary

Inhibin

Testes

Leydigcells

Testosterone (T)

To bodyfor secondary

effects

FSH

Sertolicell

Cellproducts

Secondmessenger

Sertolicell

ABP TAndrogen-binding

protein (ABP)

Spermatogonium

Spermatocyte

Accessory Glands Contribute to Semen

• Accessory glands contribute 99% of semen volume, as well as the following• Seminal vesicles – fructose, vitamin C,

prostaglandins• Prostate gland – buffers, citric acid, enzymes• Bulbourethral gland – mucus, buffers

Table 26-3

Accessory Glands Contribute to Semen

Female Reproductive System

• Female reproduction is a cyclic process• Hormones from the hypothalamus and

anterior pituitary stimulate the ovaries• The ovaries release estrogen and

progesterone in varying patterns during each cycle

• Ovulation releases a mature oocyte monthly• Estrogen and progesterone prepare the

uterus for possible pregnancy

Female Reproductive Structures

• External genitalia (aka vulva, or pudendum)• Labia majora• Labia minora• Clitoris• Vagina• Hymen

• Urethral opening is inside the labia minora

Figure 26-12a

Female Structures - External Genitalia

Vagina

Hymen(stretched)

Anus

Labiummajora

Labiumminora

ClitorisUrethralopening

THE FEMALE REPRODUCTIVE SYSTEM

ANATOMY SUMMARY

(a)

Female Structures - Internal Organs

• Vagina• Uterus• Cervix• Endometrium and myometrium

• Fallopian tube• Fimbriae

• Ovary

Uterus

Ovary

Urinarybladder

Fallopian tube

Rectum

Cervix

Anus

Clitoris

Labiummajora

Labiumminora

VaginaUrethra

THE FEMALE REPRODUCTIVE SYSTEM

ANATOMY SUMMARY

(b)

Figure 26-12b

Female Structures - Sagittal View

Ovaries: Cells and Tissues

• Follicle - structure where oocytes develop• Granulosa cells• Oocyte

• Thecal cells surround all follicles• Corpus luteum

Figure 26-12c–e

Structure of the Uterus and Ovary

Figure 26-12c, f

Structure of the Uterine Wall

Phases of the Ovarian Cycle

• Follicular phase• Proliferation of granulosa cells• Development of antrum• Maturation of oocyte

• Ovulation• Ripened follicle bursts, releasing oocyte

• Luteal phase• Ruptured follicle develops into corpus luteum

Figure 26-13 (1 of 2)

The Ovarian Cycle

Endometrial Lining: the Uterine Cycle

• Menses (occurs if pregnancy is not achieved)• Bleeding from uterus as endometrium is shed

• Proliferative phase• Endometrium grows in preparation for

pregnancy

• Secretory phase• Endometrial secretions promote implantation

Figure 26-13 (2 of 2)

The Uterine Cycle

Figure 26-13 (1 of 4)DAYS

36.4

36.7

7 14 21 28/028/0

Follicular Phase

Phases of theUterine Cycle

Phases of theOvarian Cycle

Basal bodytemperature

(–C)

Uterinecycle

Ovarianhormone

levels

Ovariancycle

Gonadotrophichormone

levels

Primaryfollicle Theca

MENSES

Inhibin

Estrogen

LH

FSH

Progesterone

Follicular Phase and Menses

Figure 26-13 (2 of 4)DAYS

36.4

36.7

7 14 21 28/028/0

Follicular Phase

Phases of theUterine Cycle

Phases of theOvarian Cycle

Basal bodytemperature

(–C)

Uterinecycle

Ovarianhormone

levels

Ovariancycle

Gonadotrophichormone

levels

Primaryfollicle Theca

MENSES PROLIFERATIVEPHASE

InhibinEstrogen

Antrum

LH

FSH

Progesterone

Follicle Maturation and the Proliferative Phase

DAYS

36.4

36.7

7 14 21 28/028/0

Follicular Phase Ovulation Luteal Phase

Phases of theUterine Cycle

Phases of theOvarian Cycle

Basal bodytemperature

(–C)

Uterinecycle

Ovarianhormone

levels

Ovariancycle

Gonadotrophichormone

levels

Primaryfollicle Theca Ovulation

Corpusluteum

formation

MENSES PROLIFERATIVEPHASE

SECRETORY PHASE

InhibinEstrogen

Antrum

LH

FSH

Progesterone

Figure 26-13 (3 of 4)

Ovulation, Luteal Phase, and Secretory Phase

DAYS

36.4

36.7

7 14 21 28/028/0

Follicular Phase Ovulation Luteal Phase

Phases of theUterine Cycle

Phases of theOvarian Cycle

Basal bodytemperature

(–C)

Uterinecycle

Ovarianhormone

levels

Ovariancycle

Gonadotrophichormone

levels

Primaryfollicle Theca Ovulation

Corpusluteum

formation

Maturecorpusluteum

Corpusalbicans

Progesterone

MENSES PROLIFERATIVEPHASE

SECRETORY PHASE

InhibinEstrogen

Antrum

LH

FSH

Figure 26-13 (4 of 4)

Corpus Luteum Degenerates and Ceases Hormone Production

Complex Hormonal Control of Two Cycles

• Ovarian and uterine cycles are controlled by several hormones, which display complex interactions

• Extra-ovarian hormones• GnRH from the hypothalamus• FSH and LH from the anterior pituitary

• Ovarian hormones• Estrogen• Progesterone

Figure 26-14

LHFSH

GnRH

Androgens

Estrogens

(a) Early to mid-follicular phase

Follicle

Granulosacells

Thecalcells

(b) Late follicular phase and ovulation (d) Late luteal phase

FSH LH

New folliclesbegin todevelop

Corpusluteum

dies

Tonic secretionresumes

Corpus luteum

Progesterone

Ovum

LHFSH

Follicle

Estrogen andprogesterone

FSH LH

Corpus luteum(from ovulated

follicle)

Estrogen

Progesterone

Inhibin

GnRHGnRH

secretes

(c) Early to mid-luteal phase

Estrogen

Inhibin

Follicle

Granulosacells

Thecalcells

Inhibin

High estrogenoutput

Small amount ofprogesterone

Androgens

LHFSH

GnRH

Pituitary Hypothalamus

Hormonal Control of the Menstrual Cycle

Hormonal Control of the Menstrual Cycle: Follicular Phase

• FSH stimulates follicular development• Maturation to secondary and tertiary follicles• Granulosa cells produce estrogen• Negative feedback decreases FSH and LH

secretion• Positive feedback allows continued estrogen

production

• LH stimulates thecal cells to produce androgens• Aromatase converts androgens into estrogens

• Antrum fills with fluid

LHFSH

GnRH

Androgens

Estrogens

(a) Early to mid-follicular phase

Follicle

Granulosacells

Thecalcells

Corpus luteum

Progesterone

Ovum

LHFSH

FollicleEstrogen

Inhibin

Pituitary Hypothalamus

Figure 26-14 (1 of 4)

Hormonal Control of the Menstrual Cycle: Follicular Phase

Hormonal Control of the Menstrual Cycle: Late Follicular Phase and Ovulation

• Late follicular phase• Secretion of inhibin and progesterone begins• Estrogen changes from negative to positive

feedback• Enhanced secretion of LH - the LH surge• Meiosis resumes in developing follicles

• Ovulation• Mature follicle secretes collagenase• Inflammatory reaction produces prostaglandins• Follicle ruptures releasing mature oocyte• Theca and granulosa cells change into luteal

cells

LHFSH

GnRH

Androgens

Estrogens

(a) Early to mid-follicular phase

Follicle

Granulosacells

Thecalcells

(b) Late follicular phase and ovulation

Corpus luteum

Progesterone

Ovum

LHFSH

FollicleEstrogen

Inhibin

Follicle

Granulosacells

Thecalcells

Inhibin

High estrogenoutput

Small amount ofprogesterone

Androgens

LHFSH

GnRH

Pituitary Hypothalamus

Figure 26-14 (2 of 4)

Hormonal Control of the Menstrual Cycle: Late Follicular Phase and Ovulation

Hormonal Control of the Menstrual Cycle: Early to Mid-Luteal Phase

• Corpus luteum develops and secretes progesterone and estrogen

• Progesterone and estrogen exert negative feedback on hypothalamus

• Effects of progesterone• Endometrium develops further• Cervical mucus thickens

LHFSH

GnRH

Androgens

Estrogens

(a) Early to mid-follicular phase

Follicle

Granulosacells

Thecalcells

(b) Late follicular phase and ovulation

Corpus luteum

Progesterone

Ovum

LHFSH

Follicle

FSH LH

Corpus luteum(from ovulated

follicle)

EstrogenProgesteroneInhibin

GnRH

secretes

(c) Early to mid-luteal phase

Estrogen

Inhibin

Follicle

Granulosacells

Thecalcells

Inhibin

High estrogenoutput

Small amount ofprogesterone

Androgens

LHFSH

GnRH

Pituitary Hypothalamus

Figure 26-14 (3 of 4)

Hormonal Control of the Menstrual Cycle: Early to Mid-Luteal Phase

Hormonal Control of the Menstrual Cycle: Late Luteal Phase

• If no implantation• Corpus luteum undergoes apoptosis after 12

days• Lack of progesterone leads to death of

endometrium• Menses = sloughing of the dead endometrium• FSH and LH secretion resumes

• Following implantation• hcG maintains corpus luteum• Corpus luteum secretes progesterone and

estrogen

LHFSH

GnRH

Androgens

Estrogens

(a) Early to mid-follicular phase

Follicle

Granulosacells

Thecalcells

(b) Late follicular phase and ovulation (d) Late luteal phase

FSH LH

New folliclesbegin todevelop

Corpusluteum

dies

Tonic secretionresumes

Corpus luteum

Progesterone

Ovum

LHFSH

Follicle

Estrogen andprogesterone

FSH LH

Corpus luteum(from ovulated

follicle)

EstrogenProgesteroneInhibin

GnRHGnRH

secretes

(c) Early to mid-luteal phase

Estrogen

Inhibin

Follicle

Granulosacells

Thecalcells

Inhibin

High estrogenoutput

Small amount ofprogesterone

Androgens

LHFSH

GnRH

Pituitary Hypothalamus

Figure 26-14 (4 of 4)

Hormonal Control of the Menstrual Cycle: Late Luteal Phase

Female Secondary Sex Characteristics

• Secondary sexual characteristics are traits, other than genitalia, that distinguish males from females

• Characteristics controlled by estrogen• Breast development• Distribution of body fat

• Adrenal androgens control some female traits• Growth of pubic and axillary hair• Sex drive (libido)