Applied Developmental Biology
Dr. Lubna Tahtamouni
The Hashemite University
7/2/2010
Week # 1
Introduction
1
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
2
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
3
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
4
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
5
6
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
7
Epigenesis Vs preformation
Organs formed from scratch
Or
Organs are already present, in miniature form,
within the egg or sperm
8
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
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Embryogenesis
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Embryogenesis
=
Fertilization
+
Cleavage
+
Gastrulation
+
Organogenesis
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THE END
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