Human Embryology – Lecture 6 (Lecture 11 + 12)
23-02-2018
Recapitulation:
Gastrulation: formation of the three embryonic germ layers (ectoderm, mesoderm,
endoderm)
Neurulation: establishing the neural tube, after induction of the ectoderm, via the
notochord.
Notochord: induction of neural plate, defines body-axis.
The Notochordal process:
- Initially the notochord starts off as a hollow tube.
- Then, the primitive pit moves more caudal while the notochord end moves
more rostral.
The Notochord is the first organ that will establish the body-axis.
Formation of the pituitary (hypophysis):
Two ectodermal parts will move towards each other and fold around each other, in
order to make up the pituitary.
Ratkhe’s pouch (part of the mouth) + the infundibulum (part of the brain –
hypothalamus) move towards each other and fold around each other, forming the
pituitary which makes up our hormones.
Development of the nervous system:
Alar (dorsal) regions – sensory
Basal (ventral) regions – motor (ganglia)
Sulcus limitans separates the motor nuclei from the sensory nuclei.
, SHH= Sonic Hedgehog Morphogen
SHH is responsible for the dorsal-ventral patterning.
Paraxial mesoderm:
Can divide into:
- Sclerotome (bones/skeleton)
- Dermatome (dermis-skin)
- Myotome (muscles)
Formation and differentiation of the sclerotome will form your vertebrate.
Vertebra are necessary in order to intentionally do things (e.g. with your hands and
feet).
Folding:
Folding of the embryo is a significant process!
Folding of the embryo happens laterally and at the head + tail.
Lateral folding: important for closure of the primitive gut.
Explanation lateral folding:
The 3-germlayers are pushed together, which will form a bridge-like round hollow
structure this will later be enclosed and forms the primitive gut.
Tadpole shape: rounded shape.
Primitive gut:
- Encloses tubular part of the yolk sac.
- Site of the future digestive tube and respiratory structures.
23-02-2018
Recapitulation:
Gastrulation: formation of the three embryonic germ layers (ectoderm, mesoderm,
endoderm)
Neurulation: establishing the neural tube, after induction of the ectoderm, via the
notochord.
Notochord: induction of neural plate, defines body-axis.
The Notochordal process:
- Initially the notochord starts off as a hollow tube.
- Then, the primitive pit moves more caudal while the notochord end moves
more rostral.
The Notochord is the first organ that will establish the body-axis.
Formation of the pituitary (hypophysis):
Two ectodermal parts will move towards each other and fold around each other, in
order to make up the pituitary.
Ratkhe’s pouch (part of the mouth) + the infundibulum (part of the brain –
hypothalamus) move towards each other and fold around each other, forming the
pituitary which makes up our hormones.
Development of the nervous system:
Alar (dorsal) regions – sensory
Basal (ventral) regions – motor (ganglia)
Sulcus limitans separates the motor nuclei from the sensory nuclei.
, SHH= Sonic Hedgehog Morphogen
SHH is responsible for the dorsal-ventral patterning.
Paraxial mesoderm:
Can divide into:
- Sclerotome (bones/skeleton)
- Dermatome (dermis-skin)
- Myotome (muscles)
Formation and differentiation of the sclerotome will form your vertebrate.
Vertebra are necessary in order to intentionally do things (e.g. with your hands and
feet).
Folding:
Folding of the embryo is a significant process!
Folding of the embryo happens laterally and at the head + tail.
Lateral folding: important for closure of the primitive gut.
Explanation lateral folding:
The 3-germlayers are pushed together, which will form a bridge-like round hollow
structure this will later be enclosed and forms the primitive gut.
Tadpole shape: rounded shape.
Primitive gut:
- Encloses tubular part of the yolk sac.
- Site of the future digestive tube and respiratory structures.
