Chapter 43, Problem 2Q

Summary Introduction

To review:

A reasonable hypothesis for the difference in effects on ectoderm-derived tissues than on mesoderm-derived tissues due to vitamin A.

Introduction:

The development of body organs in the fetus originates from the three germ layers, which are formed as a result of gastrulation (formation of the massive mass of cells) of the blastula stage of the embryo. The ectoderm is the outer germ layer, which gives rise to the epidermis, hairs, ears, mouthparts, and nervous system; the mesoderm is present in the middle and gives rise to major tissues such as bones, muscles, blood vessels, and heart; and the endoderm is the innermost germ layer that gives rise to the digestive and respiratory tracts.