Early development (dave's notes) Flashcards
What are the stages of development from day 1 to day 6?
Zygote -> morula -> blastocyst -> implantation
What is the outer layer of the developing cell mass? What does this become?
Trophoblast, becomes placenta
What is the inner layer of the developing cell mass?
The inner cell mass -> amnion and yolk sac
What divides the amnion and yolk sac divided by? What three things does this give rise to?
The embryonic plate. This gives rise to ectoderm, primary mesoderm, and endoderm
What grows from ectoderm to endoderm?
The notochord is an axial rod of cells growing from ectoderm to endoderm
Where does the neural tube develop? What does this later form?
The neural tube develops on the ectodermal surface, which is later to form the brain and spinal cord
What does the neural crest develop from? What does this form?
Cells at the edges (of what?) become isolated and develop the neural crest which becomes posterior root ganglia, ganglia of cranial nerves and autonomic ganglia
How does mesoderm lie?
In three longitudinal strips
What does the mesodermal strip nearest the midline become?
Segments into mesodermal somites which
- produce sclerotome, which surrounds the neural tube and notochord -> becomes vertebrae and dura mater
- myotome producing muscles of the body wall
What does the intermediate strip of mesoderm produce?
The intermediate cell mass and becomes segmented
What does the lateral side of the intermediate cell mass become?
The lateral side develops the pronephros, mesonephros, and metanephros
What does the medial side of the intermediate cell mass become?
The gonad and cortex of the suprarenal gland
Other than the lateral and medial side, what develops from the intermediate cell mass?
The lateral plate which is unsegmented
Why does the embryo begin to curl up?
From increased dorsal growth relative to ventral growth
What happens to the lateral plate?
The lateral plage curls around enclosing the yolk sac.
What happens to the mesoderm?
The mesoderm splits into two layers enclosing the coelom
What is the inner layer of mesoderm called? What does it become? What does it contain? What does this become?
The inner layer of mesoderm is the splanctopleure (ANS) which encloses the yolk sac (outside umbilical cord and vitellointestinal duct, inside GI)
What is the outer layer of mesoderm called? What does this become?
The outer layer is the somatopleure (somatic nerves), visceral layer supplied if at all by autonomic nerves
Where do limb buds grow from?
The lateral plate
What does the septum transverses consist of?
Mesodermal mass lying on the cranial aspect of the coelomic cavity. This develops into the pericardial membranes and part of the diaphragm, invaded by muscles from the cervical myotome.
What does the developing liver invade?
The caudal septum transversum
What happens to the septum transvedsum later in development?
It descends taking the heart with it.
What is the mouth pit called? Where does it develop?
The somatodeum forms a dimple between the forebrain capsule and pericardium
