17. Introduction to Development Flashcards
define differentiation
the process where cells specialise to perform a specific function
define morphogenesis
the process of how cells grow and develop 3-dimensionally
what are nematodes frequently used to study
neural development
why are nematodes good to study in development
they are transparent - which allows the tracking of individual cells
why are fruit flies good organisms to study development
rapid development
easy to generate mutants
what is the benefit of studying zebrafish over mice
they are cheaper to maintain than mice
why are Xenopus oocytes good to study
very large - good to generate cell extracts from
what is the benefits of studying mice
genome very similar to humans
we have good knowledge of mice genes
what are the benefits of studying chick embryos
similar to mammalian systems
tissues can be easily labelled, transplanted and cultured.
what is cleavage
cell division in the early embryo
what is gastrulation
cell movements which produce gut and three primary germ layers
describe cleavages 1 and 2
equal holoblastic
nuclei is displaced
describe cleavages 3
perpendicular but unequal holoblastic
what are the three primary germ layers
ectoderm
mesoderm
endoderm
what is the ectoderm
the outside of the embryo
what is the mesoderm
the middle lining between ectoderm and endoderm
what is the endoderm
the very inside of the embryo
what does the ectoderm go on to form
skin
nervous system
what does the endoderm go on to form
gut
liver
lungs
what does the mesoderm go on to form
the skeleton, muscle, kidney, heart
briefly describe the process of gastrulation in amphibians
- population of cells evaginate to form the blastopore
- population of cells above the blastopore migrate and extend across the embryo , pulling vegetal cells to form the archenteron
- archenteron fuses with the opposite side of the embryo
- 3 germ layers are formed
- evagination begins: blastocoel shrinks, animal pole cells undergo epiboly
what is the process of epiboly
where cells expand to completely cover the surface of the developing embryo & form the ventral lip
what is induction
where cell fates are determined via signals from other cells
what cells undergo epiboly
animal pole cells
define the term morphogen
a signalling molecule that acts directly on cells to induce a specific cellular response depending on its concentration
give an example of induction
vertebrate eye:
- eye begins as diverticula (pouches)
- pouches pinch off and form the optic cup
- induce overlying ectoderm to evaginate inwards - this forms a ball of tissue that forms the retina
- overlying ectoderm left over develops the cornea
name 2 ways how induction can occur
direct cell- cell contact
signalling molecules diffusing to distanced cells
how do we know the optic cup is inductive
when transferred to another location on the body - the optic cup induces overlying ectoderm to form the retina
= forming an ectopic eye
what is the apical ectodermal ridge responsible for
required for limb outgrowth
secretes FGF
what does the apical ectodermal ridge secrete
fibroblast growth factor (FGF)
what does the ZPA stand for, and what does it do
zone of polarising activity
controls anterior- posterior digit formation via induction
describe chick ZPA studies
transplant ZPA from posterior to anterior of a limb bud and allow it to develop
observed fusion of digit 1
= mirror image structure formed
what two tissues does kidney development begin
epithelium = uteric bud mesenchyme = metanephric blastema
which tissue induces bud branching in developing kidneys
mesenchyme (metanephric blastema)
what gene is involved in kidney development
RET gene
describe mice kidney development studies
removal of RET gene results in complete kidney growth
what 2 things can kidney growth not occur without
RET and GDNF
what secretes GDNF
the mesenchyme
who first described the concept of a morphogen
lewis Wolpert
cell fate is determined by the ………….. of the morphogen
concentration
more notes on morphogen
using textbook
yeh
