Human Development Lecture 10 – Week 3 & 4
Definitions;
• Mesoderm; derived from the mesoderm germ layer
• Mesenchyme; loos connective tissue from the cells not the germ layer
• Mesenchymal stem cells; cells from bone marrow
Gastrulation; The bilaminar disc becomes trilaminar
Bilaminar disc
• Epiblast; dorsal layer
• Hypoblast; ventral layer
Trilaminar; this germ layers are the blocks for formation of
organ rudiments.
• Endoderm; ventral layer
• Mesoderm; middle layer
• Ectoderm; dorsal layer
The primitive streak is formed in the epiblast near the caudal
end of the bilaminar embryonic disk.
From cranial to caudal; primitive groove, primitive node and
primitive pit.
The first cells that move through the primitive streak from the cardiogenetic
mesoderm (CM).
Later a thick-walled tube of mesoderm extends from the primitive node is the
notochord.
Formation of the primitive streak defines for the first time all major body axes; cranial-
caudal, dorsal ventral (already formed) and medial-lateral.
3 Germ layers;
• Endoderm; respiratory tract, digestive tract, bladder and thyroid liver and
pancreas
• Mesoderm; dermis and muscles, bone, connective tissue and lymph tissue,
reproductive system, cardiovascular system
• Ectoderm; epidermis, hair, nails, lens of eye, skin glands, central and
peripheral nervous system
First epiblast cells invaginate, displace hypoblast cells
and from endoderm.
Then intraembryonic mesoderm is formed from epiblast.
• Many subtypes; van boven naar onder
o Axial; notochord (N);
Definitions;
• Mesoderm; derived from the mesoderm germ layer
• Mesenchyme; loos connective tissue from the cells not the germ layer
• Mesenchymal stem cells; cells from bone marrow
Gastrulation; The bilaminar disc becomes trilaminar
Bilaminar disc
• Epiblast; dorsal layer
• Hypoblast; ventral layer
Trilaminar; this germ layers are the blocks for formation of
organ rudiments.
• Endoderm; ventral layer
• Mesoderm; middle layer
• Ectoderm; dorsal layer
The primitive streak is formed in the epiblast near the caudal
end of the bilaminar embryonic disk.
From cranial to caudal; primitive groove, primitive node and
primitive pit.
The first cells that move through the primitive streak from the cardiogenetic
mesoderm (CM).
Later a thick-walled tube of mesoderm extends from the primitive node is the
notochord.
Formation of the primitive streak defines for the first time all major body axes; cranial-
caudal, dorsal ventral (already formed) and medial-lateral.
3 Germ layers;
• Endoderm; respiratory tract, digestive tract, bladder and thyroid liver and
pancreas
• Mesoderm; dermis and muscles, bone, connective tissue and lymph tissue,
reproductive system, cardiovascular system
• Ectoderm; epidermis, hair, nails, lens of eye, skin glands, central and
peripheral nervous system
First epiblast cells invaginate, displace hypoblast cells
and from endoderm.
Then intraembryonic mesoderm is formed from epiblast.
• Many subtypes; van boven naar onder
o Axial; notochord (N);
