Unit 6 Reproduction and Development - PowerPoint Presentation

Slide1

Unit 6 Reproduction and DevelopmentPart 1 The Reproductive Systems

ZOOL-1072 Human Anatomy and PhysiologySlide2

FEMALE REPRODUCTIVE SYSTEMSlide3

Introduction Purpose of sexual reproduction

Fertilization

Gynecology

Diagnosis and treatment of female reproductive diseases

Urology

U

rinary system and issues with male reproductive system

Andrology

Male reproductive disorders Slide4

Female reproductive systemGonads – ovariesUterine (fallopian) tubes or oviducts

Uterus

Vagina

External organs – vulva or pudendum

Mammary glandsSlide5

Figure 28.11 Female organs of reproduction and surrounding structuresSlide6

Figure 28.11 Female organs of reproduction and surrounding structuresSlide7

OvariesPaired glands homologous to the testes

Produce

Gametes – secondary oocytes that develop into mature ova (eggs) after fertilization

Hormones including progesterone, estrogens,

inhibin

and

relaxin

Series of ligaments hold ovaries in place

Broad ligament – part of parietal peritoneum

Ovarian ligament – anchors ovaries to uterus

Suspensory ligament – attaches ovaries to pelvic wallSlide8

Figure 28.12 Relative positions of the ovaries, the uterus, and supporting ligamentsSlide9

Figure 28.13 Histology of the ovarySlide10

Histology of ovaryGerminal epithelium – covers surface of ovary

Does not give rise to ova – cells that arise form yolk sac and migrate to ovaries do

Tunica albuginea

Ovarian cortex

Contains ovarian follicles and

stromal

cells

Ovarian medulla

Contains blood vessels, lymphatic vessels, and nervesSlide11

Ovarian FolliclesOvarian follicles – in cortex; consist of oocytes in various stages of development

Surrounding cells nourish developing oocyte and secrete estrogens as follicle grows

Mature (

graafian

) follicle – large, fluid-filled follicle ready to expel secondary oocyte during ovulation

Corpus luteum – remnants of mature follicle after ovulation

Produces progesterone, estrogens, relaxin and inhibin until it degenerates into corpus albicansSlide12

Figure 28.13 Histology of the ovarySlide13

Oogenesis and follicular development

Oogenesis begins before females are born

Essentially same steps of meiosis as spermatogenesis

During early fetal development, primordial (primitive) germ cells migrate to ovaries

Germ cells then differentiate into

oogonia

– diploid (2n) stem cells

Before birth, most germ cells degenerate –

atresia

A “few” develop into primary oocytes that enter meiosis I during fetal development

Each covered by single layer of flat follicular cells – primordial follicle

About 200,000 to 2,000,000 at birth, 40,000 remain at puberty, and around 400 will mature during a lifetimeSlide14

Follicular Development – Primordial Follicles

Oogenesis begins in females before they are born

Oogonium



Primary oocyte

(2n)

Primary oocyte enters and

remains in prophase I of

meiosis

Each primary oocyte is

surrounded by

follicular

and

stromal

cells –

the

primordial

follicleSlide15

Follicular Development – Primary Follicles

Each month after puberty, several

p

rimordial follicles develop into primary follicles

Under control of FSH and LH

Primary oocyte grows in size

and forms

zona

pellucida

around itself

Follicular cells form

granulosa

cells

Stromal cells form

theca

folliculiSlide16

Follicular Development – Secondary Follicles

Primary follicles develop into secondary follicles

Theca

interna

secretes

estrogen

Theca

externa

structural

Granulosa

cells secrete

follicular fluid

in antrum

Innermost

granulosa

layer

attaches to

zona

pellucida

forming

corona

radiat

aSlide17

Follicular Development – Mature Follicles

Secondary follicle becomes mature follicle

Primary

oocyte

completes

meiosis I just before ovulation

F

irst polar body is

discarded

Secondary oocyte begins

meiosis II and awaits

ovulationSlide18

Follicular Development - Ovulation

S

econdary oocyte expelled from ovary at ovulation

If fertilized by sperm,

then secondary

oocyte completes meiosis II

S

econd polar body is discarded

Ovum unites with sperm to form a zygote (2n)Slide19

Figure 28.15 OogenesisSlide20

Tuesday Quickly review follicular development and clarify a few terms from yesterday. Continue with uterine tube, uterus, mucus, vagina, vulva, perineum, mammary glands

Tomorrow – start the female reproductive cycleSlide21

Figure 28.13 Histology of the ovary

Germinal Epithelium

Tunica

Albuginea

Ovarian Cortex

Follicles

Ovarian Medulla

Vessels Slide22

Review of Ovarian Follicles

Primordial, Primary and Secondary follicles

Contain oocytes in various stages of development

Surrounded by nourishing / hormone releasing cells:

One layer =

follicular

cells

Multiple layers =

granulosa

cells

External

stromal

cells

 synthesize ECM + collagen

Mature (

graafian

) follicle

Large, fluid-filled follicle

R

eady to expel secondary oocyte during ovulation

Corpus

luteum

(yellow body) – remnants of mature follicle

Produces progesterone, estrogens, relaxin and inhibin until it degenerates into corpus

albicans

(white body) Slide23

Outermost granulosa cells sit on basement membrane (BM)

Stromal cells become organized =

theca

folliculi

Zona

pellucida

(ZP)

– clear glycoprotein layer dev. between primary oocyte and granulosa cells as follicle growsSlide24

Antrum

– cavity fills with fluid secreted by granulosa cells

Innermost granulosa cells becomes firmly attached to ZP =

corona radiate

Slide25

Oogenesis Review Happens in ovaries each month.

The secondary oocyte took several months to mature.

If no fertilization occurs, ovulated cell degenerates.

If sperm present

 meiosis II resumes and a zygote is hopefully formed. Slide26

Uterine (fallopian) tubes or oviductsProvide a route for sperm to reach an ovum

Transport secondary oocytes and fertilized ova from ovaries to uterus

Parts (from ovary to uterus)

Fimbriae – “catches” ovum

Infundibulum

Ampulla – where fertilization often takes place

Isthmus – joins to uterusSlide27

Figure 28.16 Relationship of the uterine tubes to the ovaries, uterus, and associated structuresSlide28

Histology of the Fallopian Tubes Mucosa

Epithelium

Ciliated simple columnar cells

 conveyor belt

Peg cells

Fluid = calcium

, sodium, chloride,

glucose,

proteins, bicarbonates, and lactic acid

Lamina

Propria

Areolar CT

Folds and

papillae

Muscularis

Inner circular smooth muscle

Outer longitudinal smooth

Peristaltic contractions

SerosaSlide29

Fertilization Fertilization up to 24 hours after ovulation

Nuclei of sperm and ovum unite some hours after

Usually in ampulla – best enviro

Zygote (or oocyte) arrives

in uterus 6-7 days after

ovulation

Fertilization in the peritoneal cavity

Fimbriae didn’t sweep

ooctye

into lumen of tubes

M

issing fallopian tube on ovulation side / hormonal imbalance.

Usually still results in an intrauterine pregnancy (meaning mechanisms other than just the action of the fimbriae act on transporting the oocytes)

Sometimes results in an ectopic pregnancy (implantation outside the uterus)Slide30

UterusSize and shape of inverted pear

Nonpregnant

/ recently

pregnany

/ menopause

Functions:

Pathway for spermatozoa

Site of implantation of fertilized ovum

Fetal development during pregnancy

Labor

Source of menstruation (if implantation absent) Slide31

UterusAnatomy

Fundus

Body

Uterine cavity

Isthmus

C

ervix (opens into vagina)

Cervical canal

Normally

anteflexed

– anterior & superior over bladder

Ligaments maintain position – broad and roundSlide32

Figure 28.16 Relationship of the uterine tubes to the ovaries, uterus, and associated structuresSlide33

Figure 28.12 Relative positions of the ovaries, the uterus, and supporting ligamentsSlide34

UterusHistology – 3 layers

Perimetrium

(serosa) – outer layer

Simple squamous and areolar CT

Laterally becomes broad ligament

Myometrium – 3 layers of smooth muscle

Thickest in fundus, thinnest in cervix

Thicker middle layer = circular

Inner and outer layers = longitudinal or oblique

Contractions stimulated by oxytocinSlide35

UterusHistology – 3 layers

Endometrium

–

highly vascularized inner layer

Three components

Lumen lining

Endometrial

stroma

Endometrial glands

Two layers:

Stratum

functionalis

–lines cavity, sloughs off during menstruation

Stratum

basalis

– permanent, gives rise to new stratum

functionalis

after each menstruationSlide36

Figure 28.18 Histology of the uterusSlide37

Uterine Blood Supply

Supply blood to uterus

Supply stratum

basalis

Help regenerate stratum

functionalis

Supply stratum

functionalis

Change markedly during menstruation

MyometriumSlide38

Figure 28.19 Blood supply of the uterusSlide39

UterusCervical mucus produced by cervix mucosa

Water, glycoproteins, lipids, enzymes, and inorganic salts

Thick or thin

Thick = cervical plug, impedes sperm penetration

Thin = ovulation - more hospitable to sperm, more alkaline

Supplements energy needs of sperm

Cervix + mucus

Sperm reservoir

Protect sperm from phagocytes

Protect sperm from hostile environment of tract

Capacitation Slide40

Wednesday Notes on the vagina, vulva, perineum, mammary glands. Begin the female reproductive cycle.

Clarification from Jason on follicular anatomy:

theca

follicula

(theca

interna

/ externa)

zona

pellucida

stromal cells 

corona

radiata

basement membrane

antrum

follicular cells to granulosa cells

Friday – lab period (maybe start lecture……….)

Reminder female and male repro labs + RYK are due at the end of class

Friday

Monday – start our last topic Slide41

Vagina4” tubular

fibromuscular

canal

Lined with mucus membrane

Extends from exterior of body to uterine cervix

Functions:

Receives penis

Passageway for spermatozoa

Outlet for menstrual flow

Lower portion of birth canalSlide42

Vagina Mucosa

Muscularis

Adventitia

H

ymenSlide43

Vagina

Mucosa

Continuous with uterine mucosa

Decomposition of glycogen makes acidic environment hostile to microbes and sperm

Alkaline components of semen raise pH

Dendritic cells

RUGAE

Areolar CTSlide44

VaginaMuscularis

Smooth muscle

Outer

circular layer &

inner longitudinal

layer

Stretchy

Adventitia

Superficial layer – areolar CT

Anchors vagina to adjacent organs

Hymen

T

hin

fold of vascularized mucous

membraneSlide45

Vulva – External Female Genitalia

Mons pubis

Labia

majora

Homologous to scrotum

Labia

minora

H

omologous to spongy (penile) urethra

Clitoris

H

omologous to glans penis

Vestibule

External urethral orifice

V

aginal orifice

Homologous to intermediate urethraSlide46

Figure 28.20 Components of the vulva (pudendum)Slide47

Vulva – External Female Genitalia

Hymen

Paraurethral

(Skene’s) gland

Homologous to prostate

Greater vestibular (Bartholin’s) gland

Homologous to bulbourethral glands

Lesser vestibular gland

Bulb of the vestibule

Homologous to corpus

spongiosum

and bulb of penis Slide48

Perineum

Diamond-shaped area medial to thighs and buttocks of males and females

Contains external genitalia and anus

Figure 28.21 Perineum of a FemaleSlide49

Breasts

Breasts

– hemispheric projections

Anterior to

p

ectoralis major & serratus anterior

Fascia

Nipple

– pigmented projections

O

penings of lactiferous ducts

Areola

– pigmented area

Rough = Modified sebaceous glands

Suspensory ligaments Slide50

Mammary glands

Mammary gland

– modified sudoriferous gland that produces milk

15-20 lobes separated by adipose tissue

Lobes divided into lobules

Lobules composed of alveoli

(milk-secreting glands)

Myoepithelial

cells

Synthesis, secretion & ejection of milk = lactation

Prolactin (ant. pit.) & oxytocin (post. pit.)Slide51

Figure 28.22 Mammary Glands Within the BreastSlide52

FEMALE REPRODUCTIVE CYCLESlide53

The Female Reproductive CycleTypical duration 24-35

days; assume 28 days

Two components:

Ovarian cycle

– series of events in ovaries that occur during and after maturation of oocyte

Uterine (menstrual) cycle

– concurrent series of changes in uterine endometrium preparing it for arrival of fertilized ovum

H

ormonally regulated

Hypothalamus, anterior pituitary, ovaries Slide54

Female Reproductive Cycle Hormones

GnRH

–

Hypothalamus

Stimulates anterior pituitary release of LH and FSH

FSH

Initiates follicular growth

Stimulates ovarian follicles to secrete estrogens

LH

Stimulates ovarian follicle development and estrogen secretion

Triggers ovulation

Promotes formation of corpus

luteum

(hence luteinizing)

Stimulates production/secretion of estrogens, progesterone,

inhibin

,

relaxinSlide55

Female Reproductive Cycle Hormones

Estrogens

– secreted by ovarian follicle

s

Promotes development/maintenance of female reproductive structures and secondary sex characteristics

Stimulates protein anabolism

Lowers blood cholesterol

At times, inhibits

GnRH

, LH, FSH

Progesterone

-

secreted

mainly by corpus

luteum

Prepares uterus for implantation

Prepares mammary glands for milk production

At times, inhibits

GnRH

and LH Slide56

Female Reproductive Cycle Hormones

Relaxin

- produced

by corpus

luteum

Inhibits uterine contraction

I

ncreases flexibility of pubic symphysis

Dilates uterine cervix

Inhibin

– produced by follicles and corpus luteum

Inhibits secretion of FSH and LHSlide57

Figure 28.23 Secretion and physiological effects of hormones in the female reproductive cycleSlide58

Female Reproductive Cycle Phases

Menstrual phase

Day 1-5

Preovulatory phase

Day 6-13

Ovulation

Day 14

Postovulatory phase

Day 15-28Slide59

Menstrual Phase

FSH stimulates primordial follicles to

develop into primary

follicles

Primary follicles develop into secondary

follicles

Declining estrogen/progesterone levels stimulate ischemia in stratum functionalis

Stratum functionalis dies and is shed as menstrual discharge

Ovarian Events

Uterine Events

Day 1-5; first day of menstruation is day 1Slide60

Preovulatory Phase

Secondary follicles secrete estrogen and

inhibin

One secondary follicle becomes dominant and develops into a mature follicle

Rising estrogen levels stimulate growth of stratum functionalis

Referred to as proliferative phase

Ovarian Events

Uterine Events

Day

6

-

13Slide61

Ovulation

High estrogen levels stimulate

GnRH

and LH surge

LH surge stimulates rupture of mature follicle and release of secondary oocyte into abdominal cavity

S

tratum functionalis continues to grow

Still referred to as the proliferative phase

Ovarian Events

Uterine Events

Day

14Slide62

Figure 28.24The female reproductive cycleSlide63

High levels of

estrogens from

almost mature

follicle stimulate

release of more

GnRH and LH

LH surge

brings about

ovulation

Ovulated

secondary

oocyte

Hypothalamus

Anterior pituitary

GnRH promotes

release of FSH

and more LH

Ovary

Corpus hemorrhagicum

(ruptured follicle)

Almost mature

(graafian) follicle

LH

GnRH

1

2

3

Figure 28.25 Hormonal Control of Ovulation

Surrounded by

zona

pellucida

and corona

radiataSlide64

Postovulatory Phase

LH stimulates ruptured mature

follicle

to become corpus luteum

Corpus luteum secretes

progesterone, estrogen,

relaxin

and

inhibin

Also called the luteal

phase

Rising progesterone/estrogen levels promote

growth of

stratum functionalis (SF)

Endometrial glands in SF secrete mucus (secretory phase)

Ovarian Events

Uterine Events

Day

15-28Slide65

What Happens if the Oocyte is NOT Fertilized?

In ovary

Corpus

luteum

lifespan = 2 weeks

Corpus luteum degenerates into corpus

albicans

Progesterone and estrogen levels drop

GnRH

levels rise

GnRH

stimulates FSH/LH release; follicular growth resumes

A

new cycle begins

In uterus

Decreased progesterone/estrogen levels stimulate ischemia of stratum functionalis; menstruation beginsSlide66

What Happens if the Oocyte is Fertilized?

In ovary

Embryo secretes human chorionic gonadotropin (

hCG

)

hCG

stimulates corpus luteum to continue secreting progesterone and estrogen

Corpus

luteum’s

lifespan lasts until placenta takes over

hCG

in urine = pregnancy test

In uterus

Continued secretion of progesterone and estrogen maintain thick stratum

functionalis

, stimulate endometrial glands to secrete glycogen and inhibit menstruation

Preparatory changes peak ~ 1 week after ovulation Slide67

Figure 28.26 Summary of Hormonal interactions in the ovarian and uterine cycles