1. Applied Developmental Biology The Hashemite University
Dr. Lubna Tahtamouni
The Hashemite University
7/2/2010
Week # 1
Introduction

2. But Difference between developmental biology and embryology
Embryo: The stage between fertilization and birth
But
Do organisms ever cease to develop???????????
So, developmental biology is
Discipline that studies embryonic and other developmental* processes
* Development: slow process of progressive change

3. What is developmental biology?
- Discipline that studies embryonic and other developmental processes
Study of transient stages
Initiation and construction rather than maintenance
science of becoming, science of process

4. Questions of developmental biology
- “ It is owing to wonder that people began to philosophize, and wonder remains the beginning of knowledge” (Aristotle, Metaphysics, ca. 350 B.C.E )
- A field of science is defined by the questions it asks!
1) How does the fertilized egg give rise to the adult body?
Question of differentiation: cellular diversity
Question of morphogenesis: creation of ordered form (tissues, organs…..)
Question of growth: control over cell division
2) How does the adult body produce another adult body?
- Question of reproduction

5. We…Developmental biologists owe a lot to Aristotle
Different ways animals are born: oviparity, viviparity, or ovovivparity
Different ways cells of the embryo (blastomere) divide: holoblastic, meroblastic
Functions of placenta and umbilical cord
He thought that menstrual fluids formed the materials of embryo while semen
gave it form and animation!
Harvey
Ex ovo omnia….all from the egg
Blastoderm and germ layers
Function of amniotic fluid

7. The Aristotelian theory of male semen and female blood coagulum in the uterus
A-B. The uterus appears to be filled with the menstrual blood, C-F. upon which the semen progressively acts, building up the vessels and shaping the body's organ G. After approximately forty or ninety days, the fetus appears as formatus

8. Epigenesis Vs preformation Organs formed from scratch Or
Organs are already present, in miniature form,
within the egg or sperm

9. vertebrates , invertebrates or
Animal kingdom
vertebrates , invertebrates or
protozoa (unicellular) , metazoa (multicellular)
Metazoan = multicellular animals
Parazoa: sponges
Eumetazoa: 1. radial symmetry (diploblastic) : Cnidaria, Ctenphora
2. Bilateral symmetry (triploblastic):
deuterostomes. protostomes

16. Embryogenesis

19. Embryogenesis =
Fertilization +
Cleavage
Gastrulation
Organogenesis

22. 22

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