Lab 0 - intro

Question 1

What does it mean to have isolecithal, mesolecithal, centrolecithal and extreme telolecithal egg types?

Answer 1

isolecithal = even, sparce distribution of yolk
mesolecithal = yolk limited to the vegetal pole
centrolecithal = yolk concentrated in the middle
extreme telolecithal = dense concentration of yolk everywhere

Question 2

What is the general cleavage patterns of the following egg types: isolecithal, mesolecithal, centrolecithal, extreme telolecithal

Answer 2

• isolecithal –> equal holoblastic
• mesolecithal –> unequal holoblastic
• centrolecithal –> superficial meroblastic
• extreme telolecithal –> discodial meroblastic

Question 3

What is the difference between deuterosomes and protosomes?

Answer 3

deuterosome = mouth forms 2nd
protosome = mouth form 1st

Question 4

What does holoblastic and meroblastic refer to?

Answer 4

holoblastic = complete cleavage
meroblastic = incomplete cleavage

Question 5

Describe invagination

Answer 5

forming a cavity from the inward movements of cells (e.g. like poking a balloon)

Question 6

Describe ingression

Answer 6

When cells move from an apical to basal side

Question 7

Describe epiboly

Answer 7

When cells extend to cover another layer

Question 8

Describe involution

Answer 8

inward movement of an expanding outer cell layer so that it spreads over the internal surface of the remaining external cells

Question 9

Describe delamination

Answer 9

Separation of layers

Question 10

Describe convergent extension

Answer 10

cells intercalate with each other to converge to create a long axis