Lecture 1 Fertilization And Gastrulation

Question 1

Where does fertilization occur?

Answer 1

Distal 1/3 of ampulla

Question 2

When does cleavage occur

Answer 2

Day 3 (30 hours after fertilization)

Question 3

When does implantation occur

Answer 3

Day 6

Question 4

Capacitation

Answer 4

• takes approx 7 hours

- glycoprotein coat and seminal plasma proteins removed from plasma membrane of sperm

Question 5

Acrosome rxn

Answer 5

Release of enzymes (acrosin) allows passage of sperm through zona pellucida

Question 6

Hyluronidase

Answer 6

Allows sperm to penetrate corona radiata

Question 7

Penetration of zona pellucida

Answer 7

Using esterases, acrosin neuraminidase

Question 8

Zona reaction

Answer 8

• when 1 sperm gets through causes conformational change in zona pellucida meshwork of glycoproteins (becomes rigid)
• release of lysosomal enzymes from cortical granules near oocyte cell membrane

Question 9

What block polyspermy

Answer 9

Zona reaction

Question 10

When does morula development occur?

Answer 10

Day 3= 12-32 cells

Question 11

What days does blastocyst formation occur?

Answer 11

Day 5-7

Question 12

When does zona pellucida start degenerating and then disappear?

Answer 12

Day 5= begins to degenerate

Day 7= is gone

Question 13

What does inner cell mass give rise to?

Answer 13

Embryo

Question 14

What does trophoblast give rise to?

Answer 14

Placenta

Question 15

What is the final result of week 1?

Answer 15

• 1 layer (embryo)

- inner cell mass

Question 16

When do assisted reproductive technologies occur?

Answer 16

During week 1

Question 17

What are some assisted reproductive technologies?

Answer 17

1) in vitro fertilization and embryo transfer
2) cryopreservation of embryos
3) intracytoplasmic sperm injection

Question 18

what does trophoblast give rise to?

Answer 18

• Cytotrophoblast

- Syncytiotrophoblast

Question 19

Syncytiotrophoblast

Answer 19

-from trophoblast
-‐ Proteolytic enzymes,
chorionic gonadotropin (hcG)
‐ Responsible for
implantation and initial
signal of pregnancy

Question 20

Cytotrophoblast

Answer 20

‐ Stem cell layer

‐ Mitotically active

Question 21

Hydatidiform Mole

Answer 21

– Abnormal trophoblastic proliferation;

-excessive amounts of hCG produced

Question 22

complete mole results from

Answer 22

• Fertilization of an empty oocyte,
followed by duplication of the sperm
• Or from fertilization of an empty
oocyte by two sperm

Question 23

Partial mole results from

Answer 23

fertilization of a

normal oocyte by two sperm

Question 24

clinical features of hydatidiform mole

Answer 24

• Vaginal bleeding
• Pelvic pressure or pain
• Enlarged uterus
• Hyperemesis gravidarum

Question 25

Choriocarcinomas

Answer 25

Malignant tumor which develops from | hydatidiform mole

Question 26

what cell layers are present after week 2?

Answer 26

``` 1) – Epiblast • Ectoderm • Amnion • Amniotic cavity 2) hypoblast (only present during wk 2) ```

Question 27

hypoblast

Answer 27

– Endoderm • Prechordal plate • Primary and secondary yolk sac (umbilical vesicle) • Extraembryonic mesoderm

Question 28

prechordal plate

Answer 28

- future site of mouth | - fusion of epiblast and hypoblast

Question 29

Extraembryonic Coelom:

Answer 29

hollow cavity outside of the | embryo

Question 30

Extraembryonic Somatic | Mesoderm:

Answer 30

lining the trophoblast and covering the amnion -adjacent to ectoderm

Question 31

Extraembryonic Splanchnic | Mesoderm:

Answer 31

lining the yolk sac (umbilical vesicle) -adjacent to endoderm

Question 32

Connecting Stalk

Answer 32

``` • Extraembryonic somatic mesoderm • Forms at embryonic pole • Position changes during development ```

Question 33

Primitive Blood

Answer 33

• Extraembryonic splanchnic mesoderm • Forms in wall of yolk sac

Question 34

Chorion

Answer 34

• Extraembryonic somatic mesoderm -cytotrophoblast -syncytiotrophoblast

Question 35

placenta previa

Answer 35

- placenta implants over internal cervical os | - marginal, total, partial

Question 36

what happens in week 3?

Answer 36

gastrulation= formation of 3 primary germ layers

Question 37

Primitive Streak

Answer 37

– Primitive knot (primitive node) – Primitive groove – Primitive pit

Question 38

sacral coccygeal teratomas

Answer 38

- benign abnormal proliferation of cells | - remnant of primitive streak (cells of epiblast)(all 3 germ layers)

Question 39

notochord

Answer 39

``` • Midline • Extends from primitive node (knot) anterior to prechordal plate • Template for vertebral column • Induces neural plate ```

Question 40

notochordal plate

Answer 40

notochordal process + endoderm

Question 41

chordomas

Answer 41

``` – Rare slow growing aggressive neoplasms of bone – Arise from remnants of notochord – Occur in axial skeleton in spheno-occipital region of skull and sacral regions ```

Question 42

Allantois

Answer 42

• Endoderm • Template for umbilical arteries & vein • Becomes urachus

Question 43

paraxial mesoderm

Answer 43

– Somites • Muscle • Skeleton (Vertebral) • Dermis

Question 44

intermediate mesoderm

Answer 44

– Urogenital • Kidneys • Gonads

Question 45

lateral plate mesoderm

Answer 45

``` – Connective tissue • Blood • Lymph • Mesenteries • Cardiovascular ```