Embryology Flashcards
(20 cards)
Oocyte (ovum, egg)
female germ cell
Sperm
Male germ cell
Zygote
Diploid cell resulting from union of oocyte and sperm at fertilisation
Blastomeres
early embryonic cells
Morula
Solid mass of 12-32 blastomeres (from Latin - mulberry)
Blastocyte
Stage where morula has entered cavity and blastocystic cavity develops within
Gastrula
Stage after trilaminar embryonic disc formation
Neurula
Stage after gastrula when neural tube forms
Embryo
Developing human during embryonic stage (to end of the 8th week)
Fetus
Period from the 9th week to birth
Week 1
Fertilisation, formation of the morula and blastocyst
Week 2
Implantation of blastocyst and formation of bilaminar embryonic disc and early placenta
Week 3
Differentiation of cell layers to form the trilaminar embryonic disc
Week 4
Folding of the embryo and continuing development of the 3 germ layers (ectoderm, endoderm and mesoderm)
Week 5-8
Development of all external and internal structures (organogenetic period)
End of Week 8
Embryo looks like an ‘adult’ and is called the fetus. Growth becomes the predominant feature from this point onwards.
What comes from the ectoderm?
Skin, nervous system, neural crest (contributes to cardiac outflow, coronary arteries)
What comes from the mesoderm?
All types of muscle, most systems, kidneys, blood, bone
What comes from the endoderm?
gastrointestinal tract (liver, pancreas but not smooth muscle), endocrine organs
What is gastrulation?
Mass movement and invagination (inward folding) of the blastula to form 3 layers (ectoderm, mesoderm, endoderm)
