Exam 1 Flashcards
(212 cards)
Embryology
study of embryo until time of parturition
Parturition
Birth
Development
morphological, biochemical and physiological differentiation of an individual (embryology & gametogensis & after birth)
Differentiation
generation of cellular diversity (fertilized egg specialized into different cell types)
Morphogenesis
creation of form and structure
Growth
increase in size
Germinating
giving life
Ontogeny
growth and development of individual from fertilization to birth
Zygote
the fertilized egg
Embryo
developing organism form cleavage to birth (2 cells)
Fetus
developing embryo (in human after 3 mo.)
What are the two major accomplishments of the developmental process?
- Generates cellular diversity and order with each generation
- Ensures the continuity of life from one generation to the next
What are the 7 stages of embryogenesis?
- Fertilization (zygote formation)
- Cleavage (embryo, morula)
- Blastulation
- Gastrulation
- Organogenesis
- Germ cell formation
- Larval stage
What are the three layers formed in gastrulation?
- Ectoderm
- Mesoderm
- Endoderm
How do we approach the study of embryos (3)?
- Anatomical
- Experimental
- Genetic
What are the four parts of the anatomical study of embryos?
- Comparitive
- Teratology/Medical Embryology (limited since we can’t experiment on human embryos)
- Evolutionary
- Fate Mapping
Historical Perspective: the anatomists. How did they believe the embryo formed?
Epigenesis
Parts of the embryo arise in succession
What did Aristotle believe in?
Oviparity, vivipaarity, oviviparity
Major cleavage patterns
Functions of placenta and umbilical cord
Mensus gave material, semen gave form and animation
Historical perspective: who was William Harvey? What did he believe? He was the first to observe what?
Ex ovo omnia All animals from eggs 1st to observe chick blastoderm Blood islands form before heart Amniotic fluid functions as shock absorber
Epigenesis vs Preformation
Epigenesis: organs of embryo develop de novo
(aristotle / harvey)
Performation: tiny babies live inside of us. all generations that will ever be are within you. All orgas are pre-formed, simply required growth
What are two supporting contemporary theories of preformation?
- Infinite divisibility (things can be infinately small to serve their purpose)
- Limited time (creation to apocalypse)
Predate cell theory (didn’t understand there was a limit to how small things can be)
What are the two schools of preformation?
- Ovist
2. Spermists
What did Spallanzani believe?
Preformation
Experimented with frogs; put pants on them and stopped semen from transferring = no offspring
Established that sperm was needed to trigger the generation of offspring
Who were the Baltic Boys? What did they do?
Rathke, von Baer, Pander
Rathke - proposed how pharyngeal pouches, reproduction/extretory/respiratory system developed
von Baer - mammalian egg and notochored
Pander - primary germ layers induction