BIOM20002 Lecture Notes - Lecture 4: Primitive Knot, Neural Tube, Neural Plate
Human body develops from a single cell (the zygote)
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Development - why the adult body is the way it is (and pathologies)
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Anomalies
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Embryology and topographic anatomy
Egg fertilised in fallopian tube
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Moves into uterus, dividing on the way - one division per 24 hrs initially
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16 cell stage (3 days) is morula
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At 4 days, cell mass (blastocyst) undergoes cavitation to form a cavity (blastocoele)
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Early human development
Two types of cell: outer epithelial layer (trophoblast) and inner cell mass
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Trophoblast forms some extraembryonic structures (part of placenta)
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Between 5 and 10 days, blastocyst implants into uterine wall
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Blastocyst
3 different types of embryonic tissue - ectoderm, mesoderm and endoderm - that give rise to
distinct tissues in adult
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Process of gastrulation forms the 3 germ layers via a three dimensional reorganisation of
tissue.
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Inner cell mass splits - epiblast and hypoblast (together, bilaminar disc)
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Embryo = part of the epiblast
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Rest of epiblast and all of primitive hypoblast give rise to extra embryonic tissue
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Hypoblast + trophoblast = placenta
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At this stage the future human is a flat disc of cells
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Hypoblast extends around blastocoel to form yolk sac (humans have no yolk in the sac)
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Epiblast lines remaining smaller (amniotic) cavity
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The embryo arises from the double layer of the yellow and blue cells
Two germ layer stage
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Germ layers
4 Embryology 1
Tuesday, 29 July 2014
9:20 PM
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The embryo arises from the double layer of the yellow and blue cells
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Hypoblast forms a smaller bubble
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Ectoderm, mesoderm and endoderm form as three flat discs of cells, one on top of
another by gastrulation of two germ layer stage
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Three germ layer stage
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Gastrulation
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Document Summary
Human body develops from a single cell (the zygote) Development - why the adult body is the way it is (and pathologies) Moves into uterus, dividing on the way - one division per 24 hrs initially. At 4 days, cell mass (blastocyst) undergoes cavitation to form a cavity (blastocoele) Two types of cell: outer epithelial layer (trophoblast) and inner cell mass. Trophoblast forms some extraembryonic structures (part of placenta) Between 5 and 10 days, blastocyst implants into uterine wall. 3 different types of embryonic tissue - ectoderm, mesoderm and endoderm - that give rise to distinct tissues in adult. Process of gastrulation forms the 3 germ layers via a three dimensional reorganisation of tissue. Inner cell mass splits - epiblast and hypoblast (together, bilaminar disc) Rest of epiblast and all of primitive hypoblast give rise to extra embryonic tissue. At this stage the future hu(cid:373)a(cid:374) is a at disc of cells.
