Fertilisation To Trilaminar Embryology

Question 1

What receptor does sperm bind to on the ovum

Answer 1

Glycoprotein ZP3 on the zona pellucida

Question 2

How does the sperm penetrate the zona pellucida

Answer 2

Release o acrosomal enzymes

Question 3

What are the 3 components of a sperm head

Answer 3

Acrosome
Sperm nucleus (haploid)
Plasma membrane

Question 4

Why do the plasma membranes of the sperm and ovum need to fuse

Answer 4

So nucleus of sperm can enter

Question 5

What does the entry of sperm into the ovum trigger

Answer 5

Completion of meiosis 2
Release of cortical granules by oocyte

Question 6

What is the function of cortical granules

Answer 6

Hardens zona pellucida prevent polyspermate

Question 7

What is the opening for ovum to enter the uterine tubes called

Answer 7

Uterine abdomen oss

Question 8

What happens to the overall size of the zygote structure

Answer 8

Doesn’t change, blastomere cells get smaller

Question 9

What types of cell does up to the 8 cell stage blastomere contain

Answer 9

Totipotent

Question 10

What is a totipotent cell

Answer 10

Can form any cell type
Embryonic cell
Placental cell

Question 11

What is mosaicism / mitotic nondisjunction

Answer 11

2 different cell lines with different chromosome compliments
(E.g. if 1 cell divides unevenly where 1 daughter cell has 1 chromo and another has 3, only affects those 2 cells not all cells)

Question 12

How does compaction of the morula

Answer 12

Confined within zona pellucida
To make max use of space, cells become tighter and form cell junctions
Outer-cells form gap junctions

Question 13

What happens when outer cells in contact with the zona pellucida form gap junctions

Answer 13

Fluid enters through the zona pellucida

Question 14

What are the 4 components of the blastocyst

Answer 14

Trophoblas (embryonic part of placenta)
Zona pellucida
Blastocyst cavity
Inner cell mass (forms the embryo)

Question 15

How does blastocyst hatching occur

Answer 15

Trophoblas broken down
Cell bundles contract to burst out allowing implantation

Question 16

Where does implantation occur

Answer 16

Directly on the endometrial lining on the superior aspect of the posterior uterine wall

Question 17

What is the function of the corpus luteum

Answer 17

After ovulation, follicle develops into corpus luteum which secretes progesterone

Question 18

What is the function of progesterone

Answer 18

Maintain thick endometrial lining for implantation

Question 19

What are the 2 cell layers of the bilaminar embryo

Answer 19

Epiblast
Hypoblast
Amniotic cavity also begins to form in embryo

Question 20

What do trophoblast (outer cell mass) develop into

Answer 20

Cytotrophoblast
Syncytiotrophoblast

Question 21

What is the function of the synctiotrophoblast

Answer 21

Produces human chorionic gonadotropin (hCG)
Stimulates corpus luteum
Drives invasion of endometrial lining

Question 22

What surface of the embryo os the epiblast

Answer 22

Dorsal

Question 23

What surface of the embryo is the hypoblast

Answer 23

Ventral

Question 24

Where does the amniotic cavity form

Answer 24

Epiblast

Question 25

Where does the primitive yolk sac form

Answer 25

Hypoblast

Question 26

When implantation is complete how is the small gap closed

Answer 26

Fibrin coagulum

Question 27

Where do lacunae form

Answer 27

In the synctiotrophoblast

Question 28

How does oxygen diffuse to the embryo

Answer 28

Uteroplacental circulation Maternal blood flows into lacunae to diffuse to the embryoblast

Question 29

What is formed after the extraembryonic mesoderm develops then degenerates

Answer 29

Chorionic cavity

Question 30

What forms the definitive yolk sac

Answer 30

A second wave of hypoblasts

Question 31

As the chorionic cavity develops what other structure develops

Answer 31

Connecting stalk

Question 32

What entirely encircles an implanted embryo

Answer 32

Chorionic cavity

Question 33

What structure separates the amniotic sac and definitive yolk sac

Answer 33

Bilaminar embryonic disc

Question 34

What are the abnormal sites where implantation can occur

Answer 34

Ovary Uterine tube Peritoneum

Question 35

Where does the primitive streak appear

Answer 35

Midline at caudal end of epiblast

Question 36

What is found at the cranial (head) end of the primitive streak

Answer 36

Primitive pit Primitive node

Question 37

What does the primitive streak consist of

Answer 37

Pit Node Groove

Question 38

What is the function of the primitive pit

Answer 38

Helps with the rotation of folds ( sets up body axis)

Question 39

What are hypoblast cells replaced by

Answer 39

Definitive endoderm

Question 40

How are the 3 germ layers formed

Answer 40

Movement of epiblast cells through the primitive streak

Question 41

How does the misoderm form

Answer 41

Cells migrate through the primitive streak between epiblast and endoderm Epiblast becomes ectoderm

Question 42

What does the ectoderm form

Answer 42

Epidermis of skin Nervous system

Question 43

What is the notochord

Answer 43

Transient embryonic anatomical structure with the 3 regions of the mesoderm at each side

Question 44

What are the 3 regions of the mesoderm

Answer 44

Paraxial Intermediate Lateral plate

Question 45

What are the 2 layers of the lateral plate mesoderm

Answer 45

Somatic layer - body Visceral layer - organs

Question 46

What does the paraxial mesoderm form

Answer 46

Vertebral column Skeletal muscle Parts of the dermis

Question 47

What does the intermediate mesoderm form

Answer 47

Urogenital systems Kidney and ureter Primary and secondary reproductive organs

Question 48

What does the somatic layer of the lateral plate mesoderm form

Answer 48

Most of the dermis Lining of body wall Parts of limb

Question 49

What does the visceral layer of the lateral plate mesoderm form

Answer 49

Cardiovascular system Lining of organs Smooth (involuntary) muscle

Question 50

What does the endoderm form

Answer 50

Lining of gut tube Lining of respiratory tract Lining of bladder and urethra