chapter 1 Flashcards
(32 cards)
what is development?
process of change where a multicellular organism arises from a single cell
what is a zygote?
when a sperm cell and an egg fuse together
when does a zygote turn into an embryo?
when fertilization begins; when the cells start to divide
what is gastrulation?
the movement of cells in regards to one another
what are the layers of the gastrula?
ectoderm, mesoderm and endoderm
what is a germ cell?
a cell during embryo development that will turn into a sperm or egg
what is organogenesis?
cell to cell signaling occurs and cells starts forming systems
what is metamorphosis of the frog?
loses tail and gains legs, loses teeth to be able to become a carnivore and the gills regress due to the frog being terrestial.
what did william harvey say about amniotic fluid?
described it as shock absorbing fluid for the embryo
what did von haller and bonnet say?
species remain constant, tissues could unravel at different rates so the embryo does not appear like an adult
who created the cell theory?
schleiden and schwann
who discovered the three germ layers?
christian pander- tripoblastic embryos have an ectoderm, mesoderm and an endoderm
what did karl ernst von baer discover?
the notochord and the mammalian egg
what are blastomeres?
cells in the cleavage stage
what is a vegetal pole?
hemisphere that is yolk rich
what is an animal pole?
hemisphere with lower yolk concentration
what is holoblastic cleavage
complete cleavage; isolecithal (equal) and mesolecithal (moderate)
what is meroblastic cleavage?
incomplete; telolecithal and centrolecithal- dense yolk that takes up more of the cell volume
what are the two major cell types?
epithelial and mesenchymal
What is invagination?
I folding of a sheet of cells much like a stress ball being poked
What is involution?
Inward movement of the outer layer so if spreads over the internal cells
What is ingression?
Migration of individual cells into interior, cells become mesenchymal ( separated) and migrate independently
what is delamination?
splitting cellular sheet into two more or less parallel sheets- similar to ingression bur forms a new sheet
what is epiboly?
movement of sheets spreading as a unit to enclose deeper layers of the embryo- can occur by cell division/shape change
