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Summary - Class notes - Mens- en dierkunde1
1426287600 Thema 1: H3+H4 part 1
What is a blastomere?Blastomere is a large cluster of small cells formed during cleavage
When is the blastula stage?at the end of cleavage
What is cleavage?celdeling
Why is the animal-vegetal axis formed?because yolk only exists at 1 end, creating polarity
Which pole is the animal pole and which is the vegetal pole?yolk rich = vegetal
other end = animal
What does isolecithal egg mean?Iso=equal. Eggs with little yolk that is evenly distributed.
what is an mesolecithal egg?meso=middle. Egg with moderate amount of yolk at vegetal pole
What is telolecithal?telo=end. abundance of yolk at vegetal pole.
What does meroblastic cleavage mean?Mero=part. That there is much yolk and therefore the cleavage is incomplete because cleavage furrows cannot cut through dense yolk.
What does holoblastic cleavage mean?That the cleavage furrows extend completely through the egg. Little yolk is present.
Cleavage divides the mass of the zygote until a cluster of cells called the blastula is formed. Cells are arranged around a central fluid-filled cavity called the blastocoel.
What is gastrulation?convertion of the blastula into a 2 or 3 layered embryo.
What are the layers formed by gastrulation called?germ layers
What is invagination and what does it form?invagination is when 1 side of the blastula bends inwards. This forms a new cavity called gastrocoel, archenteron or oerdarm.
What is a blastopore?opening to the gut where invagination began.
Gastrula has 2 layers.
outer layer = ectoderm (ecto=out, derm=skin).
Inner layer = endoderm (endo=inside).
Mesoderm lies between ectoderm and endoderm.
Describe the 2 ways in which mesoderm can be formed?
- Schizocoely: cells arise from ventral area near blastophore lip and spread into space between archenteron and outer cell wall. --> protostomes
- Enterocoely: central region of archenteron wall puches outward into space between archenteron and outer body wall. --> deuterostomes
What is coeloom?body cavity completely surrounded by mesoderm.
What is induction?capacity of some cells to evoke a developmental response, such as change in cell shape in other cells. Tissues influence eachother.
What is the primary organizer and why?The dorsal lip, because it is the only tissue capable of inducing development of a secondary embryo in the host.
The inductive event of the primary organizer is called primary induction because it is the 1st inductive event in development.
What is epigenesis? And what are its 3 steps?view that an embryo develops and differentiates step by step from a zygote undergoing cell division.
- pattern formation
- determination of positions in the body
- induction of limbs and organs appropriate for that position
Latest added flashcards
- Lange (pijp) beenderen
Diaphyse, twee epifysen, mergholte. bv femur.
- Platte beenderen
Twee cortices met spongiosa. bv frontale.
- Korte beenderen
Geen mergholte bv hielbeen.
- Samengestelde beenderen
- Enchondrale (kraakbeen) verbening. Indirect, eerst een kraakbeen stadium.
- Desmale (via fibreus bindweefsel) verbening. Direct in de huid. Oppervlakkige schedelbeenderen. Huidplaten in fossiele vissen. Sleutelbeenderen.
- Buitenkant: compacta = corticaal bot
- Binnenkant: spongiosa
- Osteoblasten: aanmaak
- Ostercyten: mechanosensor
- Osteoclasten: afbraak
- "Beton": hydroxyapetiet (Calcium!)
- Vezels: collageen
- Fibreus. Veel collageen (ook type I). In menisci, tussenwervelschijven.
- Elastisch. Veel elastine. In oor, neus, larynx (=strottenhoofd).
- Hyalien. Weinig vezels (vnl collageen type II). In gewrichten, rond luchtpijp.
- Chrondroblasten: voorlopers chondrocyten
- Chondrocyten: kraakbeen aanmaak!!
- Extracellulaire matrix
- "Gelei" betsaande uit proteoglycanen en glycoproteinen
- Vezels: collageen en elastine.
- Bot (=been)
- Andere bindweefsels zoals ligamenten en gewrichtskapsels