Lecture 10 - Embryology I Flashcards
What is the structure of a blastocyst?
Blastocoel cavity
Trophoblast around outside
Inner cell mass
Describe the initial stages of development
Fertilisation in the Fallopian tube
Morula: 3 days
Blastocyst: 4 days
What does the trophoblast become?
Extraembyronic tissue
What does the inner cell mass become?
Epiblast and hypoblast
When does the embryo implant?
5-10 days
What is the bilaminar disc?
This is the epiblast and hypoblast
NB Gastrulation has yet to occur
Describe the process of gastrulation
Primitive streak appears on epiblast
Thickens –> primitive groove
Cells migrate medially, then down through the primitive node
Endoderm forms, pushing away hypoblast
Cells migrate on top of endoderm to form mesoderm
Cells left form the ectoderm
What is the fate of the different cells types in the bilaminar embryo?
Part of the epiblast: embryo
Some epiblast + hypoblast : extra embryonic tissue
How does the notochord form?
Cells migrating through primitive node and anterially form the mesodermal notochord
What are the derivates of ectoderm?
Skin
Nervous system
What are the derivate a of mesoderm?
Pleura Dermis Skeleton Haematopoetic tissue Vasculature Heart Walls of organs Muscles
What are the derivatives of endoderm?
Endothelium of hollow organs
Gastrointestinal tract
Respiratory endothelium
Describe the formation of the nervous system
Aka neurulation
Mesodermal notochord induces overlying ectoderm to form neural plate
Neural groove forms on ectoderm
Ectoderm raises up on the sides, and meets in the middle to form the neural tube
Neural crest cells migrate and go on to form many types of structures
What are the derivatives of neural crest cells?
Dentine Bones and cartilage of face Melanocytes Sympathetic and parasympathetic ganglia Posterior root ganglia Enteric ganglia Schwann cells
Describe what happens to the neural tube once it forms
Vesicles form, giving rise to he brain and the spinal cord
