Lecture 5

Question 1

Microlecithal

Answer 1

Small amount of yolk
mammals
egg holder is source of nutrients

Question 2

Mesolecithal

Answer 2

Medium amount of yolk
Amphibians
Produces larval form that must get own nutrients to undergo metamorphosis

Question 3

Macrolecithal

Answer 3

Large amount of yolk
Bird and reptiles
provide enough energy to produce an adult-like form.
newly hatched reptiles able to feed on their own

Question 4

isolecithal

Answer 4

yolk evenly distributed throughout egg (microlecithal)

Question 5

Telolecithal

Answer 5

Animal pole and vegetal pole result from polarity of yolk in egg

Question 6

Frog Embryo Development

Answer 6

Three perpendicular cleavages. Formation of blastoceol. Formation of germ layers

Question 7

Frog gastrula to body plan

Answer 7

Surface layer of cells covering castrocoel will undergo neurulation. Forms CNS

Question 8

ICM

Answer 8

Becomes embryo, amnion, yolk sac, allantoic stalk

Question 9

Trophoblast

Answer 9

Becomes placenta

Question 10

Cytotrophoblast

Answer 10

chorion—> placenta

Question 11

Syncytiotrophoblast

Answer 11

Trophoblast lacunae

Question 12

List advantages for embryos developing in an aquatic environment

Answer 12

CO2 and O2 diffuse readily w/ embryo
Nitrogenous waste products can be readily excreted
Desiccation is reduced

Question 13

List disadvantages for embryos developing in a terrestrial environment

Answer 13

Have to keep cell membranes moist
Water not present to dilute nitrogenous waste
Food for developing embryo may not be readily available in terrestrial env.

Question 14

Amnion

Answer 14

Protects from desiccation

Question 15

Chorion

Answer 15

Gas exchange (forms placenta)

Question 16

Yolk sac

Answer 16

holds yolk or prelim site for formation of blood cells and germ cells

Question 17

Allantois

Answer 17

Store nitro waste

Umbilical cord