Chapter 1 Flashcards
what are the seven stages of embryogenesis?
- gametogenesis
- fertilization
- cleavage
- gastrulation
- organogenesis
- larval stage
- maturity
what occurs during gametogenesis?
sperm and oocyte come together
what occurs during fertilization?
zygote forms
what occurs during cleavage?
rapid mitotic cell division
-the cytoplasm is divided into smaller cells called blastomeres that form a morula (big ball of cells)
-the cells start to turn into a blastula with a hollow center
what occurs during gastrulation?
formation of the primordial germ cell layers
-the fluid-fill cavity (blastocoel) allows for morphogenesis
-a pore (blastopore) starts to form on the opposite side of sperm entry allowing for the cells to migrate and form layers creating a dorsal lip
what type of movement occurs during gastrulation to form the blastopore?
invagination
what are the three germ layers and what to they become?
endoderm: gut
mesoderm: NS, skin
ectoderm: muscle, cartilage, bone
what occurs during organogenesis?
cells form tissues and organs (NS FIRST)
what is a neurual?
ectoderm forms a tube (neural tube)
what are somites?
paired blocks of mesoderm, repeats
(ribs, spinal cord)
what is the notocord?
sends signals to cells for what to become and where
-organizing factor
what occurs during the larval stage?
hatching, birth
-longest stage
what occurs during the maturity stage?
the organism becomes sexually mature
what are the eight famous developmental biology researchers in order?
- Aristotle (350 BC)
- Harvey (1651 AD)
- Malpaghi (1672 AD)
- Wolff (1767)
- Pander (1817)
- von Baer (1828)
- Darwin (1842)
- Weismann (1875)
what is Aristotle known for?
believed that menstrual fluid and sperm made a baby (sperm carved the fluid)
-oviparous, viviparous, ovoviviparous
-placenta, umbilical cord
what is the difference between oviparous, viviparous, and ovoviviparous?
oviparous: egg
viviparous: alive birth
ovoviviparous: egg hatches inside
what does holoblastic and meroblastic mean?
holoblastic: everything divides
meroblastic: only embryo divides, not yolk
what is William Harvey known for?
ex ovo omnia
- everything comes from egg, even viviparous
-studied chick blastoderm (appeared as red dot)
-amniotic fluid & jelly coat
what Marcello Malpaghi known for?
believed in preformation (homounculus, unrolled)
-everything already in sperm, just very tiny, then it unrolls in the egg
-used a microscope to look at early stages of embryos
-able to see primordial groove, somites, circulatory system
what is Kaspar Friedrich Wolff known for?
discovered epigenesis (de novo)
-saw flat tissue bend to form sheets, materials divide to form something different
-something forms from nothing!
-vis essentialis (essential force)
-there is a force in the universe that pushes things in the world to become more complex
what is Christian Pander known for?
discovered the triploblastic “three-layers”
took advantage of the growing universities
INDUCTION = each layer tells the other layers what to do
what is Karl Erst von Baer known for?
discovered THE EGG
-made four principles
what are the von Baer principles?
- the general features of large group animals appear before specialized features of small group animals (head -> feathers, scales, skin)
- less general features come from more general features (limbs -> wings, fin)
- embryo of a species departs instead of passing through lower animals (gill arch example)
- early embryos of higher animals only resemble lower animal embryos, never the adult form
what is Charles Darwin known for?
embryonic resemblances = species connectedness
-things that looked alike as embryos shows community of decent
embryonic resemblances are inappropriate to adult forms (python has legs as embryo)
late- & post- embryonic adaptations are caused by adult form , not embryonic lifestyle
what is Weismann known for?
studied viceroy & monarch butterflies
-identical adult, different embryo
what is homology?
similar structures arise from a common ancestor
-wing vs arm
-gill arch
what is analogy?
similar structures arise from similar function, not ancestor
-bird wing vs butterfly wing
what is fate mapping?
trace cell lineage & follow a single cell to watch and see what it becomes
-very difficult
what is grafting?
took chick (host) and quail (donor) cells because they have same antibodies
-able to follow the darker quail nucleus in the chick to see what it becomes
what is audioradiography?
made donor cell radioactive and were able to track the cell through development in the host
-same species!
what is vital & fluorescent tracing?
dyed a clump of cells and followed them
what is morphogenesis?
how we generate shapes
-cellular connects, cell divisions, cell shape, cell movement, cell growth, cell death, cell secretions (sticky, push away, signals)
what is the difference between mesenchymal cells and epithelial cells?
mesenchymal: loosely packed, not attached to each other
epithelial: intercalated (sheets), start as layers
what are the 6 ways mesenchymal cells do morphogenesis?
Condensation (becomes epithelial)
Cell Division
Cell Death
Migration (move at certain times)
Matrix Secretion & Degradation (removal of layers)
Growth (hypertrophy)
what are the 7 ways epithelial cells do morphogenesis?
Dispersal (becomes mesenchymal)
Ingression (cells move from outward to inward)
Change Shape or Growth (remain attached but change)
Migration (form fewer rows)
Cell Division (w/in column or row)
Matrix Secretion & Degradation (removal of layers)
Migration (formation of free edges)
what is invagination?
infolding of sheet
what is involution?
inward movement to inner side of exterior cells
what is ingression?
surface cells move inward
what is delamination?
splitting of sheets to form more layers
what is epiboly?
movement of sheets as a unit to enclose deep layers
what is a defect? what are the two main types?
something that lacks as a result of incompleteness, inadequacy, or imperfection
-malformation, disruption
what is a malformation?
GENETIC
-instructions wrong in genes
-mutation, aneuplodies, translocation (break point)
what is Piebaldism?
neural crest cells lacking KIT protein
-leads to white marks on forehead & stomach
-has other symptoms associated
what is a disruption?
ENVIRONMENTAL
-caused by teratogens
how is thalidomide an example of a disruption?
drug given to pregnant women in the 50s, led to prevented limb growth in the child
what is a syndrome?
collection of symptoms that occur together due to one break in the DNA
what does congenital mean?
disease or abnormality present at birth
what is allometry?
growth of different body parts at different rates (baby head)
what did Alan Turing do?
cracked the german “enigma” code and helped win WW2
created the Reaction-Diffusion Model
what is the reaction-diffusion model?
Substance P: producer, slow, local travel
Substance S: stopper, fast, distant travel
-creates a gradient where cells in the middle get more P and cells on the outside get more S
