1.3 How Are You?

Question 0

Name the three primary germ layers and state some of the major organs they generate.

Answer 0

Ectoderm - skin & nervous system

Mesoderm - bones, kidney, pancreas, facial muscle

Endoderm - primitive gut, thyroid, lungs

Question 1

Are organs created through epigenesis or through performation? Please explain through the history of embryology.

Answer 1

The players

The progression of debates

Current revelations

Question 2

State Von Baer’s laws.

Answer 2

1. The general features of a large group of animals appear earlier in development than do the specialized features of a smaller group.
2. Less general characters develop from the more general, until finally the most specialized appear.
3. The embryo of a given species, instead of passing through the adult stages of lower animals, departs more and more from them.
4. Therefore, the early embryo of a higher animal is never like a lower animal, but only like it’s early embryo.

Question 3

Name the three major branches that form the anatomical approach to development

Answer 3

1. Comparative embryology
2. Evolutionary embryology
3. Teratology

Question 4

Name the 3 methods of birth

Answer 4

1. Oviparity
2. Viviparity
3. Ovoviviparity

Question 5

Name the two major patterns of cleavage.

Answer 5

1. Holoblastic - the entire egg is divided into smaller cells (frogs & mammals)
2. Meroblastic - only part of the egg is destined to become the embryo.