BIO190: The Class: Evolution: Lesson 9

Development

Central Question---How is it possible that a fertilized egg can form into an individual animal?

Key events in animal development

1. Gamete formation (Sperm and eggs form and mature) ->

2. Fertilization (Sperm and egg fuse forming zygote) ->

3. Cleavage (Zygote divides, forming blastomeres) ->

4. Gastrulation (Germ layers form) ->

5. Neurulation (Neural tube forms) ->

6. Organogensis (Formation of organs) ->

7. Growth (Organs increase in size)

• egg

• sperm

• zygote

• blastomere

• preformation

• epigenesis

• fertilization (fig. 7-4)

• cleavage

• radial

• regulative

• spiral

• mosaic

• polarity

• blastula

• blastocoel

• invagination

• archenteron

• blastopore (fig. 7-10)

• Protostomia (examples of animal phyla)

• Deuterostomia examples of animal phyla)

• three germ layers (fig 7-25)
  1. ectoderm (gives rise to epithelium of body surface and nervous sys)
  2. mesoderm (gives rise to muscular, reproductive sys; peritoneum)
  3. endoderm (gives rise to epithelium of digestive tube)

• diploblastic

• triploblastic

• coelom

• formation of coelom (fig. 7-10)
  1. schizocoelous (fig. 10-13)
  2. enterocoelous (fig. 10-13)

• homeobox concept in development

• Amniotes (reps,birds, and mammals)

• Three membranes of the amniotic egg (fig. 7-21)
  1. amnion
  2. allantois
  3. chorion

  Once you have completed the lesson, you should go to Assignment 7-1.

  E-mail Sylvester Allred at Syl.Allred@nau.edu
  

  ---

  

  Copyright 1997 Northern Arizona University
  ALL RIGHTS RESERVED