Early Embryonic Formation

Question 1

How does cavitation occur?

Answer 1

Sodium being pumped actively into central area -> osmotic pressure causes cavity to expand

Question 2

Epiblast

Answer 2

Superficial layer - embryonic body

Question 3

Hypoblast

Answer 3

Deep cell layer form extraembryonic membranes

Question 4

What is gastrulation?

Answer 4

Where disc becomes trilaminar (ectoderm, mesoderm, endoderm)

Question 5

Tissues the ectoderm forms

Answer 5

Epidermis of the skin, hair, mouth and nose lining, skin glands, nervous system

Question 6

Tissues the mesoderm forms

Answer 6

Dermis of the skin, muscle, skeleton, circulatory system, gonads kidneys, outer layers of digestive and respiratory tracts

Question 7

Tissues the endoderm forms

Answer 7

Lining of the digestive and respiratory tracts, liver, pancreas

Question 8

The primitive streak

Answer 8

forms in early amniotes and establishes bilateral symmetry

Question 9

Polarisation

Answer 9

Tail end = node signalling centre
Head end = anterior visceral endoderm (AVE) signalling centre

Question 10

MAKE CARDS REGARDING SIGNALS AND SYMMETRY

Question 11

Monozygotic twins are

Answer 11

One egg and one sperm split into two at an early stage

Question 12

Dizygotic twins are

Answer 12

Two eggs fertilised at the same time by two separate sperm