Early Embryonic Developement Flashcards
look at embryos to…
-describe the evolution of life and how different animals form their organs
veterinarian interest
common abnormalities
- missing limbs
- missing/extra digits
- cleft palate
teratogen definition
any agent or facotr that can cause congenital anomalies in a embryo or fetus
teratogen factors
- genetic factors
- radiation
- hormones
- chemical agents
- infectious agents: viruses, parasites
tertogenic influences on development
- at predifferentiation: embryo dies
- organogenesis: structural defects
- fetal growth: affects functional maturation
zygote
single cell, large
morula
compact mass of cells,
blastula
fluid-filled cyst with cells at periphery,
early gastrula
bilaminar disk
late gastrula
trilaminar disk to tube shape
order of cell devolpement
zygote,morula, blastula, early gastrula, late gastrula
four basic tissues
epithelium, connective tissue, muscle, nervous tissue
Cleavage: Morula
16 cells, ‘mulberry’, zona pellucida still intact, late morula has 32 cells
Cleavage: Blastocyst
cavity begins to form, outer cell mass (trophoblast) and inner cell mass (embryoblast) present. no overall change in size from zygote-‘compaction’–>zona pellucida is shed shortly-‘hatching’ of blastula–>expanded blastocyst
Cleavage: gastrula
formation of 3 germ layers & primitive axial organs: neural tube, notochord, somites, and primitive gut
blastogenesis
compaction occurs as cell division occurs, no increase on overall size of embryo while inside zona pellucida
trophoblast
will form part of placental membranes
inner cell mass
embryoblast: will form entire embryo, forms bilaminar disc of epiblast and hypoblast; establishes dorsal and ventral axis
ectoderm
derived from epiblasts
form: epithelium, nervous tissue, and neural crest cells
mesoderm
connective tissue, muscle, enothelium, mesothelium, urogenital system
endoderm
epithelium of digestive and respiratory systems
-derived from hhypoblas
epithelium derived from
all three layers
gastrulation
formation of 3-layered embryo, begins with the formation of the primitive streak in epiblast
ectoderm
formed by epiblast cells that migrated toward primitive streak
primary endoderm
formed by the replacement of hypoblast/endoblast cells, also lines the yolk sac
mesoderm
formed from cells migrating from primitive streak
notochord
cluster of cells derived from mesoderm, determines axis of embryo and required to signal neural tube formation from neuroectoderm
mesoderm inductive effects:
- forms notochord
- notochord induces ectoderm to form neural tissue
- neural tube and neural crest cells formed
- some somites seen
- lateral, cranial. caudal body folds create head, tail, primitive anus and mouth
- nervous system defines
neural tube formation
- neural ectoderm thickens
- neural folds dip down producing the neural groove
- neural folds contact, neural ectoderm cells rearrange
- form the neural tube with overlying
parts of mesoderm
- axial: notochord
- paraxial: somites
- intermediate: urinary/gential
- lateral plate
somites
division of animal’s body giving rise to muscle, cartilage, tendons, dermis, limbs, vertebrae
- dermatome: dermis
- myotome: skeletal muscle
- sclerotome: cartilage,tendons,endothelia, forms axial skeleton
cranial part of neural tube
brain, in skull
caudal part of neural tube
spinal cord, will be in vertebral (neural) canal of the back bone
neural crest cells
transient, multipotent, migratory cell population unique to vertebrates that give rise to a diverse cell lineage including melanocytes, craniofacial cartilage and bone
