Chapter 28.1, Problem 5MI

Summary Introduction

To summarize:

Information about two major characteristics of vertebrates.

Introduction: Vertebrates are animals with backbones. Most chordates are vertebrates. Vertebrates have a vertebral column and specialized cells that develop from the nerve cord. The vertebral column also called spinal cord is the main feature of all vertebrates.

Answer to Problem 5MI

	Vertebral Column	Neural crest
Formation	Thenotochord is replaced by vertebral column during embryonic development.	As the nerve cord is forming in the embryo. A layer of ectoderm pinches off just before the tube closes.
Functions	It surrounds and protects the dorsal nerve cord.	Many vertebrate features such as parts of brain, skull, few sense organs, parts of pharyngeal pouches, nerve fibers, insulation for nerve fibers and some gland cells develop from it.

Explanation of Solution

Chordates have four main features- a dorsal tubular nerve cord, a notochord, pharyngeal pouches, and a postanal tail.

In most vertebrates, the notochord is replaced by vertebral column that surrounds and protects the dorsal nerve cord. Notochord is replaced during the embryonic development. Cartilage is the main building material of vertebral column.

As the nerve cord forms during embryonic development in vertebrates, a neural crest is formed. A neural crest is a group of cells that develop from a nerve cord. A layer of ectoderm cells just above the notochord folds in to form the nerve cord. Just before the tube closes, a strip of cells pinches off forming a neural crest. This is a small group of cells but is of great significance as many important vertebrate features develop from the neural crest. These features include parts of brain, skull, few sense organs, parts of pharyngeal pouches, nerve fibers, insulation for nerve fibers and some gland cells.