Transcript Embryology Notes

Early Human
. Development.
Reproductive System
week 10
Prenatal Development
Embryonic
development
fertilization - 8 weeks
Fetal
development
9 weeks - birth
time period from fertilization to birth = gestation
Postnatal Development
Oocyte at Ovulation

Oocyte (egg) released from ovary in
Metaphase II.
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Occurs on Day 14 or 15 during menstrual
cycle.
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Spike in LH & FSH
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Travels down fallopian tube.
Fig 28-1
Fertilization
Taking place in ??
Viability of gametes:
– Oocyte 12-24 h
– Sperm 12-48 h
During Menstrual Cycle, Uterus wall
becomes thicker.
Menses won’t occur when fertilized egg,
successfully, attaches to thickened uterine wall.
The first Trimester
weeks 1-12; fetus size ~ 3 in.; weight ~ 14 g
Cleavage
Implantation
Placenta
Embryogenesis
Basic organ plan and tissues laid out –
most susceptible to damage or
disorganization at this time
Cleavage
Early division of zygote into multiple cells
without increase in size, partitions
contents
Morula
solid ball of cells
Zygote
Blastocyst
with blastocoele cavity
Day 10
Embryo completely
embedded in
uterus
Blastula forms first.
Pluripotent Stem
cells present!!
Placenta begins to form.
Gastrulation: 3 Germ Layers Formed
Ectoderm
Nervous system
Skin
Endoderm
Digestive System
Mesoderm
Heart, Lungs, Muscles
day 12:
Play-Doh Embryo
Development Lab
Mr. Gairani
Zygote
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Totipotent
Gives rise to every
cell type in the body
Plancenta
Morula
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Cells divide my
mitosis
Totipotent
Identical twins arise
from this stage
Blastula

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3rd day after conception
Hollow ball of cells
Outer layer becomes
the placenta
Inner cell mass are
embryonic stem cells!!
Stem cell lines
Pluripotent
Gastrula

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14 days after
fertilization
3 germ layers
– Endoderm
– Mesoderm
– Ectoderm

Multipotent