1030- Developmental Biology Flashcards
How many layers does gastrulation give rise to ? and what are their names?
Ectoderm, Mesoderm and endoderm
What is the fourth germ layer called?
The neural crest
What are the derivatives of the three embryonic germ layers?
Ectoderm: Nervous system and skin
Mesoderm: Muscle, Skeleton, Kidneys and the reproductive system.
Endoderm: Endocrine glands, Lungs, digestive tract and liver.
Blastocyst
The cell structure which forms the inner cell mass which forms the embryo .Outer layer is called the trophoblast.
When do most organs develop within the embryonic period?
Within 3-8 weeks of human development.
What factor is the largest cause of human embryonic malformations?
Unknown factors
What factor is the smallest cause of human embryonic malformations?
Environmental factors
What are the four causes of human embryonic malformations?
Multifactorial inheritance, unknown factors, environmental factors, Genetic factors.
What are teratogens?
substances that may cause birth defects via a toxic effect.
Ectodermal Abnormalities
Spina Bifida
Mesodermal defects
making different digits, Arm to leg transformation, skeletal defects.
Neural tube defects:
failure to close the neural tube.
Polydactyly:
A gain of Shh signalling due to ectopic expression of Shh. Shh acts as a
morphogen to specify digits
Leg to Arm Transformation:
Due to ectopic misexpression of Pitx1 (which specifies legs
during normal development) in the developing arms.
Spondylocostal Dystosis :
due to loss of function mutations in the Notch signalling
pathway
