Early development Flashcards
Zygote
Morula?
Blastomere
Newly fertilized ovum after mitotic divisions
Compaction
?
Morula
Compacted balstomeres - a.k.a zygote
Enters uterus, 3rd/4th day after fertilization
Blastocyst
Morula that has entered uterus
has a cavity, and inner (future embryo) and outer layers (trophoblast)
Trophoblast
Outer cell layer of blastocyst
Bilaminar germ disc
?
CLeavage
Mitotic Divisions
Gastrulation
development of ecto, endo, meso derm from epiblast
Ectoderm = forms what
Neural plate - nervous system,
Primitive Spinal cord
**sensory epithelium all over body outside body
Mesoderm = forms what
Somites
=Vertebral Column & Tendons/Cartilage/Bone
=Muscle
=Connective Tissue
Urogential Structures
Lining of intraembryonic Cavity and organs
Primordial Germ Cells - location
Wall of Yolk Sac
migrate to Gonadal Ridge
Fertilization preparation
Spermatozoon must penetrate corona radiata, zona pellucida and oocyte cell membrane
Fertilization result
Restoration of diploid number of chromosones, determination of sex and intiation of cleavage
Fertilization location
ampulla of uterine tube
Implantation
Blastocyst implanted within uterine cavity
help from throphoblast cells
Ecpotic pregnancy
implantation of blastocyst outside uterine cavity
Thropholbast devenpolment
turns into cytothrophoblast and synctiothrophoblast that grow into endometrium
Gastrulation process
begins with formation of primitive streak on dorsal srface of epiblast
cells of epiblast migrate toward primitive streak and form endoderm
Other cells btwn epiblast and endoderm form mesoderm
Remaining cells for ectoderm
Trilaminar disc
3 distinct germ layers
ectoderm, mesoderm, endoderm
Notochord
Extends from primitive node to oropharyngeal membrane and plays an inductive role in organ formation
Embryonic disc
flat rounded sturcture, undergoas folding to form body cavities
Nerurulation
notochord induces ectoderm to thicken and form neural plate (neuroectoderm)
neuroectoderm
Gives rise to spinal cord
Neural crest cell
migrate through embryo to form adult structures
Any interuption in mitosis or migration of neural cells can proiduce developmental defect. KNOW
KNOW
Mesoderm - layers
Paraxial, Intermediate and Lateral plate mesoderm
Endoderm
GI tract, Respiratory tract lining, parenchyma, stroma, lining bladder, urethra +
