Lecture 11: Early Embryonic Development Flashcards
What are the defining structures of vertebrates?
The defining structures are a segmented backbone, or vertebral column surrounding the spinal cord, with the brain at the headed end enclosed in a bony cartilaginous skull
What axis together define the left and right side of the animal?
Antero-posterior and dorso-ventral axes
Where do vertebrates have a general bilateral symmetry?
Around the dorsal midline
What are the three germ layers, and what does each give rise to?
- endoderm - give rise to gut and its derivatives such as liver and lungs
- mesoderm - give rise to skeleton, muscles, connective tissue, kidney, heart and blood
- ectoderm - endoderm of the skin and nervous system
What is the earliest structure of mesodermal structure that can be easily recognized? does it persist? if not, what does it develop into?
Rod shaped notochord. does not persist and develops into the vertebral column that forms the spine
What are the axial structures?
the notochord, neural tube, somites and vertebral column
Describe how the mammalian embryo gets nourishment
the egg of most mammals are small and non-yolky. mammalian embryo is nourished for the first few days by fluids in the oviducts and uterus.
What happens when the egg is implanted in the uterus wall?
the mammalian embryo develops specialized extra-embryonic membrane to provide nourishment via placenta
What is the difference between amniotes and anaminotes? Provide an example of each.
Birds and mammals both of which develop extra embryonic membranes called amnion are known as amnions.
Amphibians and fish which do not are called anaminotes
What will the vegetal region give rise to? what about the animal region?
vegetal region - endoderm
animal region - ectoderm
What is succeeded by gastrulation?
neurulation - the formation of the neural tube. early embryonic precursor of the CNS
