transport of gametes and fertilization

7/28/2019 Transport of Gametes and Fertilization

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TRANSPORT OF

GAMETES ANDFERTILIZATION

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STIGMA apex of protrusion of follicle bulging from the

surface of the ovary


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Summary of Events in the Egg Cell after LHsurge from the Anterior Pituitary

a. Increased vascular permeabilityb. Leak of plasma proteins into the tissues

resulting in local edema;

c. Secretion ofhyaluronic acid by granulosacells resulting in loosening of granulosalayers;

d. Weakness of the outer follicular wall due todeath of some overlying cells;

e. Increased antral fluid pressure (about 5-6mm of H2O)


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Structures observed in an ovulated egga. the ovumb. the zona pellucidac. the corona radiata* (2 to 3 cell layers)d. sticky matrix containing surrounding cells of the

cumulus oophorus


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Signs of Ovulation

a. Mittelschmerz (German for middle pain)b. Slight rise in basal body temperature


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EGG

TRANSPORT>


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Immotile Cilia Syndrome normallyfertile

Uterine Tube x-s


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Ectopic pregnancy usually occurs 99% of cases inthe uterine tube. It can be found in1. Ampullary (54%)2. Isthmic (25%)3. Fimbrial (17)4. Interstitial (2%)5. Ovarian (0.5%)6. Cervical (0.3%)7. Abdominal On Intestine (1.2%)

8. Abdominal On Rectouterine pouch (0.05%)


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Tubal Transport 3 to 4 days regardless of whether fertilization occurs

AMPULLA

ISTHMUS

INTRAMURAL

INCREASEDPROGESTERONE LEVELS


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72 hours

8 hours

If fertilization has not occurred, the egg degenerates and is

phagocytized.


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SPERM

TRANSPORT>


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Spermatozoa spend from 4to 8 days in the epididymis


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Seminal Vesicles (60%) Prostate Gland (30%)

Fructose Citric acid

Prostaglandins Acid phosphatase

Zinc

Magnesium ions

Volume of ejaculate 2 to 6 mL

Number of spermatozoa 40 to 250 millionpH 7.0 to 8.3


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2 Modes of Sperm Transport throughthe Cervix

a. Fast Phase Some spermatozoa can reach the

uterus within an hour of

ejaculation (relies on muscularmovements of the femalereproductive tract)

b. Slow Phase Involves swimming of spermatozoa

through the cervical mucus Rate of travel = 2 to 3 mm/hr


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IM HERE!


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The Function of

the CorpusLuteum ofOvulation,and Pregnancy>


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CHORIONIC GONADOTROPIN protein hormone secreted byfuture placental tissues that help in maintaining functionalconditions of corpus luteum.


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Corpus albicans


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Fertilization

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Penetration of theCorona Radiata

Attachment to andPenetration of the

Zona Pellucida

Acrosomal Reaction

Binding to Plasmamembrane and

entry into the egg


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Plasma membrane of the egg

13 micronsthick in humans


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IMPORTANT ROLES OF THE ZONA PELLUCIDA

1.It serves as a barrier that normally allowsonly sperm of the same species to accessthe egg

2.After fertilization, the modified zonapreventspolyspermy;

3.During the early stages of cleavage, it actsas a porous filter through which certainsubstances secreted by the uterine tubecan reach the egg

4.It normally prevents prematureimplantation of the cleaving embryo intothe wall of the uterine tube.


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Plasma membrane of the egg

13 micronsthick in humans

Corticalgranules


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SOME MAJORE MAMMALIANACROSOMAL ENZYMES

Acid proteinaseAcrosinArylaminidaseArylsulfataseCollagenaseEsterase-galactosidase-glucoronidaseHyaluronidaseNeuraminidase

Phospholipase CProacrosin


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PREVENTION TO POLYSPERMY

Slow Block to Polyspermy

Fast Block to Polyspermy

Cortical granules from egg release its contents to theperivitelline space then to the zona pellucida wheresperm receptors are hydrolyzed

Observed in organism that fertilize externally.


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IMPORTANCE OF FERTILIZATION

1.STIMULATES THE EGG TO COMPLETE SECONDMEIOTIC DIVISION

2.RESTORES THE NORMAL DIPLOID NUMBER OFCHROMOSOMES

3.DETERMINES THE SEX OF THE FUTUREEMBRYO

4.CAUSES METABOLIC ACTIVATION OF THE EGG,WHICH IS NECESSARY FOR CLEAVAGE AND

SUBSEQUENT EMBRYONIC DEVELOPMENT TOOCCUR


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Days relative to ovulationProbability

ofFertilization


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transport of gametes and fertilization

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