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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

SISTEMA REPRODUCTORSISTEMA REPRODUCTOR

(LA IDEA FIJA)


• How male and female reproductive systems differentiate

• The reproductive organs and how they work• How gametes are produced and fertilized• Pregnancy, stages of development, birth &

lactation

• Reproductive and developmental maturation and aging


Sex Determination: OverviewSex Determination: Overview

• Dimorphism:• Males → sperm• Females → eggs

• Chromosomes• Autosomes• Sex Chromosomes

• X - chromosome• Y - chromosome

Figure 26-1: Human chromosomes


Sex Determination: OverviewSex Determination: Overview

Figure 26-2: Inheritance of X and Y chromosomes


Sexual Differentiation: Internal Embryonic DevelopmentSexual Differentiation: Internal Embryonic Development

• Bipotential tissues: genes & hormones direct differentiation

• Gonad → testis or ovary• Wolffian duct → Vas deferens, Mullerian duct →

oviduct


Sexual Differentiation: Internal Embryonic DevelopmentSexual Differentiation: Internal Embryonic Development

Figure 26-3a: Sexual development in the human embryo


Sexual Differentiation: External GenitaliaSexual Differentiation: External Genitalia

• Bipotential tissues: genital tubercle, urethral folds, urethral groove and labioscrotal swellings


Sexual Differentiation: External GenitaliaSexual Differentiation: External Genitalia

Figure 26-3b: Sexual development in the human embryo


Determination of sex

• Determined genetically by two sex chromosomes: XY or XX.

• Y is dominant and contains the testis-determining gene product.

• Only one X is active. The other X condenses to form the Barr body:

• Occasionally, more than one copy of X or Y occurs: XXX, XXY, XO or XX/XY mosaic being the four most common abnormalities.


Regulation of Reproduction: General PathwaysRegulation of Reproduction: General Pathways

• Hypothalamus: pulse generator• Gonadotropin releasing H

• (GnRH)• Anterior Pituitary

• Lutenizing H (LH)• Follicle stimulating H (FSH)

• Ovary: progesterone• Estrogen, inhibin

• Testis: testosterone


Regulation of Reproduction: General PathwaysRegulation of Reproduction: General Pathways

Figure 26-7: General pattern of hormonal control of reproduction


Pathway for Sexual Development: Review for Genes to OrgansPathway for Sexual Development: Review for Genes to Organs

Figure 26-4: Role of the SRY gene in male development


Hypothalamus-Pituitary-Gonadal Axis

GnRH GnRHHypothalamus

Androgenicand anabolic

effects

Oestrogeniceffects

Testis Ovary

StimulatoryInhibitory

AnteriorPituitaryLH LH

FSH FSH

LeydigCells

Thecainterna

SertoliCells

Granu-losa

Inhibin Inhibin

Testosterone Oestrogen

Androgens

Gonads


Male Reproductive Anatomy and PhysiologyMale Reproductive Anatomy and Physiology

• Testis• Epididymis• Vas deferens• Seminal vesicle• Prostate• Bulbourethral• Ejaculatory duct• Urethra• Penis


ComponentsComponents

• Testis => spermatozoa; testosterone production• Epididymis => spermatozoa maturation & storage• Ductus deferens & ampulla => transport & semen• Accessory glands => semen

• a) Prostate gland• b) Vesicular glands (seminal vesicles)• c) Bulbourethral (Cowper’s) gland• d) Distal portion of ductus deferens (+/- ampulla)

• Urethra => transport• Penis=> transport and ejaculation


Male Reproductive Anatomy and PhysiologyMale Reproductive Anatomy and Physiology

Figure 26-9a: ANATOMY SUMMARY: Male Reproduction


Spermatogenesis: Sperm Production in the TestisSpermatogenesis: Sperm Production in the Testis

• Seminiferous tubules• Spermatids • Spermatocytes• Spermatozoa• Sertoli cells

• Interstitial tissue• Leydig cells• Capillaries


Spermatogenesis: Sperm Production in the TestisSpermatogenesis: Sperm Production in the Testis

Figure 26-9b-e: ANATOMY SUMMARY: Male Reproduction


Interstitial cells (of Leydig)

S T

Cells of Leydig

ProduceAndrogens—

mainly Testosterone


Organization of Testis


Seminiferous Tubule and Interstitial Cells


Regulation of SpermatogenesisRegulation of Spermatogenesis

Figure 26-11: Hormonal control of spermatogenesis


Regulation of SpermatogenesisRegulation of Spermatogenesis

• GnRH → LH → Leydig cells → testosterone → 20sex charact.

• GnRH → FSH → Sertoli cells → spermatoctyematuration

• Inhibin feedback – FSH, testosterone – short & long loops


Blood-Testis BarrierBlood-Testis Barrier

• Adjacent sustentacular cells are joined by tight junctions• Forms a diffusion barrier = controlled microenvironment for

spermatogenesis

• Separates basal region from tubular compartment• Spermatogonial cell division (mitosis) occurs in basal

compartment

• Meiosis and spermiogenesis occurs in tubular compartment• Blood-testis barrier prevents many substances from entering

the tubular compartment

• Spermatocytes pass through the intercellular junctions to enter the tubular compartment


FSH RECEPTORFSH RECEPTOR


Overview of Gametogenesis: Producing Eggs or SpermOverview of Gametogenesis: Producing Eggs or Sperm

Figure 26-5: Gametogenesis


Spermatozoa Structure and Functions in ReviewSpermatozoa Structure and Functions in Review

• Head• Acrosome:• Nucleus:

• Midpiece• Centrioles:• Mitochondria:

• Tail: flagellum• Microtubules:

Figure 26-10: Sperm structure


LH & FSH RECEPTOR MUTATIONSLH & FSH RECEPTOR MUTATIONS


Female Reproductive Anatomy and Physiology: OverviewFemale Reproductive Anatomy and Physiology: Overview

• Ovary• Fallopian tube

• Fimbriae• Uterus

• Cervix• Endometrium

• Vagina• Clitoris• Labia


Female Reproductive Anatomy and Physiology: OverviewFemale Reproductive Anatomy and Physiology: Overview

Figure 26-12b: ANATOMY SUMMARY: Female Reproduction


Ovary: Details of Histology & PhysiologyOvary: Details of Histology & Physiology

• Follicle• Oocytes• Thecal cells• Granulosa cells

• Estrogen• → Corpus luteum

• Corpus luteum• Progesterone• Inhibin



Figure 26-12d: ANATOMY SUMMARY: Female Reproduction



• Follicle• Oocytes• Thecal cells• Granulosa cells

• Estrogen• → Corpus luteum

• Corpus luteum• Progesterone• Inhibin


Follicular StructureFollicular Structure


Menstrual Cycle: Egg Maturation, and Endometrial GrowthMenstrual Cycle: Egg Maturation, and Endometrial Growth

• Follicular phase• Egg matures

• Ovulation• Egg released

• Luteal phase• Corpus luteum• Endometrium • Prep for blastocyst

• No Pregnancy• Menses

Figure 26-13: The menstrual cycle


Figure 28.26 The Hormonal Regulation of the Female Reproductive CycleFigure 28.26 The Hormonal Regulation of the Female Reproductive Cycle

Figure 28.26a-c


The Hormonal Regulation of Ovarian ActivityThe Hormonal Regulation of Ovarian Activity

Figure 28.25


Follicular Growth RegulationFollicular Growth Regulation

• GnRH rises in response to a decline in inhibin and sex steroids

• GnRH stimulates rise in pituitary FSH & LH secretion.

• FSH stimulates new follicle growth

• LH induces thecal cell growth, vascularization & androgen synthesis

• FSH stimulates granulosa cell production of E2 & LH receptor


Follicular Growth Regulation 2Follicular Growth Regulation 2

• LH act on thecal & granulosa cells and FSH acts on granulosa cells

• Late follicular phase has elevated follicular fluid E2, P, FSH and LH but low androgens


Endocrine Control of Menstrual Cycle: Follicular PhaseEndocrine Control of Menstrual Cycle: Follicular Phase

• FSH stimulates follicular development• Estrogen: + feedback, limits more follicles


Endocrine Control of Menstrual Cycle: OvulationEndocrine Control of Menstrual Cycle: Ovulation

• ↑ Estrogen → LH "surge" & FSH spike → egg release• Inhibin↑ pushes FSH down , ↓ new follicle development


OvulationOvulation

• The stigmata, a cone-shaped protrusion of the follicle wall, appears just before ovulation

• Preovulatory follicular fluid has elevated E2, P, FSH, LH, oxytocin, plasmin activity & collaginase activity

• Extensive follicular vascularization occurs immediately prior to ovulation


Endocrine Control of Menstrual Cycle: Follicular Phase and OvulationEndocrine Control of Menstrual Cycle: Follicular Phase and Ovulation

Figure 26-14a,b: Hormonal control of the menstrual cycle


Endocrine Control of Menstrual Cycle: Luteal phaseEndocrine Control of Menstrual Cycle: Luteal phase

• Granulosa cells form corpus luteum → progesterone• ↑ progesterone & estrogen maintain endometrium• Inhibin continues to limit new follicular development


Corpus Luteum Development 1Corpus Luteum Development 1

• LH stimulates thecal & granulosa cell invasion of follicular cavity

• LH induces the luteinization of both cell types

• P synthesis increases as number of luteal cell increase



• LH stimulates increased P & E secretion

• FSH has no direct role in corpus luteum (CL) maintenance

• CL function depends on adequacy of follicle development (adequate induction by FSH of E2, LH and LDL receptor levels)

• Failure of adequate CL function results in luteal insufficiency



• Estrogen induces luteolysis

• Luteolysis causes decreased E2 & P secretion leading to decreased plasma levels

• Luteolysis continues in the absence of a fertilized ovum


Endocrine Control of Menstrual Cycle: Late Luteal phaseEndocrine Control of Menstrual Cycle: Late Luteal phase

• Pregnancy: maintain ↑ progesterone, estrogen &inhibin

• No pregnancy: ↓ progesterone, estrogen &inhibin

• Menses, ↑ FSH & LH → new follicle development


Endocrine Control of Menstrual Cycle: Luteal phase and Late Luteal phaseEndocrine Control of Menstrual Cycle: Luteal phase and Late Luteal phase

Figure 26-14c, d: Hormonal control of the menstrual cycle


The Uterine CycleThe Uterine Cycle

Figure 28.20


The Hormonal Regulation of the Female Reproductive CycleThe Hormonal Regulation of the Female Reproductive Cycle


Menstrual Cycle: Egg Maturation, and Endometrial GrowthMenstrual Cycle: Egg Maturation, and Endometrial Growth

• Follicular phase• Egg matures

• Ovulation• Egg released

• Luteal phase• Corpus luteum• Endometrium • Prep for blastocyst

• No Pregnancy• Menses

Figure 26-13: The menstrual cycle


Overview of the Menstrual CycleOverview of the Menstrual Cycle

SISTEMA REPRODUCTORSex Determination: OverviewSex Determination: OverviewSexual Differentiation: Internal Embryonic DevelopmentSexual Differentiation: Internal Embryonic DevelopmentSexual Differentiation: External GenitaliaSexual Differentiation: External GenitaliaDetermination of sexRegulation of Reproduction: General PathwaysRegulation of Reproduction: General PathwaysPathway for Sexual Development: Review for Genes to OrgansHypothalamus-Pituitary-Gonadal Axis

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