Zusammenfassung der Ressource
Prenatal Periods
- Germinal period-
period of the Zygote
- period of rapid
cell replication
- conception till
implantation (end of
second week)
- formation
of the
blastocyst
with two
layers
- outer cell
mass:
trophoblast
layer
- inner cell mass:
embryonic disk
- Embryonic period
- implantation till
the end of the
eight week of
gestation
- eight week-
movement
begins and
bones begin to
harder
- basic organs are
formed
(organogenesis) and
embryo responds to
direct stimulation
- embryonic
disk is
differentiated
into three cell
layers
- ectoderm-
nervous
system,
skin and
hair
- mesoderm-
muscles,
bones,
circulatory
system and
internal
organs
- endoderm-
digestive system,
lungs, urinary
tract and glands
- Foetal period-
period of the
foetus
- organs take their
final forms and
begin to function
(histogenesis)
- divided
into
trimesters
(3 periods
of 3
months)
- begins two thirds of
the way through the
first trimester and
ends at birth (8th
week - birth)