History Flashcards
Who was the first to address embryology as a field?
Aristotle
What did Aristotle look at to answer what question?
Look at chicken eggs during different stages of development to answer how does an egg grow into an organism
What are the 3 variations on animal life cycle themes outlined by Aristotle?
Viviparity, oviparity, ovoviviparity
What is viviparity?
Birth of a live organism after maturing and developing inside the mother
What is oviparity?
Birth from an egg
What is ovoviviparity?
Egg hatches inside the mother and leaves through live birth
What are the two cell cleavage patterns outlined by Aristotle?
Holoblastic and meroblastic
What did Marcello Malpighi observe?
Development of blood vessels and heart in chicken embryos
What did Anton wan Leewenhoek study?
Eggs and sperm
What is preformation?
Sperm and eggs contain a tiny person that just gets bigger
Who were the supporters of preformation?
Marcello Malpighi and Charles Bonnet
What is epigenesis?
Organs develop de novo in the new organism
Who were the supporters of epigenesis?
Aristotle and William Harvey
Who found solid evidence for epigenesis?
Kaspar F. Wolff
What did Kaspar F. Wolff observe?
De novo development of organs and organ systems in chicken embryos
Who discovered germ layers?
Heinz Christian Pander, Heinrich Rathke, and Karl Ernst von Baer
How were germ layers discovered?
Cells were labelled with stains and tracked throughout development
What are the 3 germ layers?
Ectoderm, endoderm, mesoderm
What do cells in the ectoderm become?
Epidermis, neurons, pigment cells
What do cells in the endoderm become?
Stomach and thyroid cells, lung cells, germ cells
What do cells in the mesoderm become?
Notochord, bone tissue, kidney cells, red blood cells
What is a triploblastic animal?
An animal where all 3 germ layers are present
What is a diploblastic animal? Which phylum is diploblastic ?
An animal where only 2 germ layers are present, with no mesoderm. Cnidaria
Why is the saying “ontogeny recapitulates phylogeny” wrong? Who said that?
Development doesn’t actually tell us very much about evolutionary relationships. Ernst Haeckel
What are the 5 features of phylum chordata?
Notochord, post anal tail, dorsal hollow nerve chord, endostyle, pharyngeal gill slits
What are von Baer’s laws?
- General features of a broad group will appear earlier in development than specialized features of a smaller group
- During development, general features give rise to more specific features
- The embryo of higher animals doesn’t pass through the adult stage of a lower animal
- The embryo of higher animals is never like the the adult of a lower animal, but will share features with a lower animal’s embryo
What did Spemann and Mangold discover?
Spemann’s organizer and principle of induction
