Embryonic Development Department of Biology, WCU
Introduction Differentiation Periods of development Embryonic Fetal Childhood Adolescence Adulthood Senescence
Embryogenesis 1. Fertilization zygote
Embryogenesis 2. Cleavage rate of mitosis is high morula
Embryogenesis 3. Blastocyst blastocoel trophoblast inner cell mass
Implantation
Embryogenesis 4. Blastula trophoblast expands in size bilaminar germ disk
Embryogenesis 5. Bilaminar disk amniotic space yolk sac (gut, early RBC’s) amnion (enclose embryo)
Embryogenesis 5. Gastrulation Primitive streak Primitive knot Bilaminar to a trilaminar disk ectoderm endoderm Primitive streak Primitive knot
Gastrulation Trilaminar disk Mesoderm
Gastrulation 6. Trilaminar disk Bilaminar areas Stromodeum Proctodeum oropharyngeal membrane cloacal membrane Stromodeum Proctodeum
Differential Growth
Neuralation 7. Notochord from mesoderm vertebrates begins nerve cord
Neuralation 8. Neural tube spina bifida
Neurulation 9. Neural tube neural crest cells: PNS neural tube: CNS
Body folding Umbilical cord
Mesoderm A. Somites Sclerotome: vertebrae, ribs Dermatome: dermis of skin Myotome: muscles
Mesoderm B. Intermediate mesoderm gonads, kidneys, adrenal cortex
Mesoderm C. Lateral plate mesoderm somatic mesoderm splanchnic mesoderm