Development Flashcards
we all start out as what?
single cells
what are the three cellular events in development?
- proliferation
- migration
- differentiation
what is the order of structures formed once we start from a single cell?
zygote, morula, blastula, gastrula, neurula
when the first sperm enters the egg what occurs?
we get depolarization causing the release of Ca2+ ions which causes changes in the zona pellucida to prevent entry of other sperms.
what is the blastocyst made up of?
outer layer of cells called trophoblast, inner cell mass and a fluid filled cavity called the blastocele.
what forms the fetal portion of the placenta?
trophoblast and part of inner cell mass (parts of blastocyst, rest of inner mass forms embryo)
morphogenesis occurs by what?
polarity and tubular organization (gastrula)
neural tube formation (neurula)
neural crest cells
somites
organogensis occurs by what?
developmental fields and stem cells/progenitors.
morphogenesis and organogenesis involves the control of what? which is determined by the combination of?
phenotypic expression
determined by environmental and genetic factors.
Control mechanisms for phenotypic expression (altering the genome which produces changes in phenotype) are?
- epigenetics
- transcription factors
- Growth factors
which HOX gene defines the eye?
PAX i.e. this the pax gene was put on the leg, an eye would develop on the leg.
which ocular structures grow from the surface ectoderm?
- epithelium of conjunctiva and lids
- corneal epithelium
- lens
which ocular structures arise from the neuroectoderm?
retina/RPE
ciliary epithelium
iris epithelium and dilator muscle
nerves (i.e. ciliary and choroidal nerves)
what ocular structures arise from the neural crest?
corneal keratocytes (stroma) and conreal endothelium
TM
iris stroma, melanocytes, sphincter muscle
ciliary body (muscle and connective tissue)
most of choroid and sclera
Which ocular structures arise from the mesoderm?
endothelium of BV and schelmms canal
caudal ventral part of the sclera
extraocular muscles
where does the blastocyst implant?
uterine wall
the inner mass of the blastocyst forms what two cavities? and what are their functions?
yolk sac (in humans produces blood cells and future sex cells and gut) and amniotic cavity (cavity in which embryo floats).
of the three primary germ layers, the bulk of the eye is made from which layer?
ectoderm.