Chapter 1 Flashcards
(50 cards)
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
