Basic Embryology Flashcards
What does congenital mean?
Present at birth, acquired at development in the uterus and not necessarily inherited.
First few phases of early embryonic development
Zygote, morula (proliferation occurs to form this), blastocysts (embryonic stem cells), bilaminar germ disc, trilaminar germ disc
What layers are formed during the late blastocyst stage?
Ectoderm and endoderm
What are the layers of the trilaminar disc and what is it’s formation called?
Formation of the trilaminar disc = gastrulation
Ectoderm, mesoderm and endoderm
How is the mesodermal layer created?
Along the primitive groove in the ectodermal layer, the ectodermal cells divide and migrate to form through this streak and invaginate underneath this layer. They move laterally and forwards between the ectoderm and endoderm, creating the mesodermal cell layer between.
What do mesodermal layers contribute to?
Formation of connective tissue, e.g., bone and cartilage
From mesenchymal, mesodermal derived stem cells
What cells are derived from the ectodermal layer?
Neural crest cells are derived from the neuronal tube of the ecoderm. Main cells in tissues that contribute to endogenous repair processes. Neural crest cells migrate throughout the developing embryo, especially to craniofacial region.
What else happens as the neural tube is developed?
Massive expansion of the head region, forming forebrain, midbrain and hindbrain. Cranial facial tissues are folded. Maxillary and mandibular processes seen.
What are cranial neural crest cells?
Multi potent stem cells derived from ecto-mesenchymal cells. Remain in tissues after development (e.g., in dental pulp or PDL). Play a crucial role in the regeneration of tissues.
What do cranial neural crest cells contribute to?
Development of the craniofacial complex - connective tissue, cartilage, bone and teeth (e.g., odontoblasts, pulp, cementum, PDL), articulating disc of TMJ and branchial arch ganglia.
Where do neural crest cells form?
At the dorsal/lateral aspects of neural folds - the neural crests
What is seen during folding of the embryo?
Formation of the primitive oral cavity (stomatodeum) and early jaw development from the first branchial arch.
What forms the ectomesenchyme?
Cranial neural crest cells migrate to developing face and branchial arches to form ectomesenchyme.
Which branchial arch does the jaw and teeth develop from?
First branchial arch forms the lower jaw process and starts tooth develoment. Week 6.
Tissue differentiation and morphodifferentiation
Early development followed by organ development at 5-6
Primitive vascular circulation and brain wave activity
