What happens at the mid-blastula transition in Xenopus? Which part of the Xenopus blastula becomes the mesoderm? Where does the dorsal lip tissue end up when, Xenopus gastrulation is finished? Where does the vegetal pole end up when gastrulation is finished? How is the central nervous system formed? Where does the neural crest come from and what does it become? What are the main tissue types formed from the mesoderm? What happens during the cortical rotation? What is the principal determinant for endoderm formation in Xenopus? What are the main mesoderm-inducing factors in Xenopus? Solution 2. Midblastula transition refers to a number of dramatic changes that occur at this stage in Xenopus. The important event that happens during this stage is activation of zygotic genes. The Cell cycle is lengthened, the asynchronous cycle of different cells. Development of cellular motility. 3. The blastula is composed of three different regions out of which the equatorial or marginal zone, which compose the walls of the blastocoel differentiate primarily into mesodermal tissue. 4. The lip of the blastopore nearer to the animal pole is termed the dorsal lip of the blastopore. The dorsal lip of the blastopore forms due to the contraction of bottle cells. It becomes the head and the dorsal midline structures all along the body. It forms notochord, flanking parts of somites, floor plate of neural tube. 5. The vegetal plate undergoes primary invagination to produce the archenteron or primitive gut. Primary invagination is thought to result from changes in the shape of cells in the vegetal plate. 6. During the development, the dorsal ectoderm rolls up into a tube, which becomes the brain at the anterior end and the spinal cord at the posterior end. 7. The neural crest is a population of migratory cells, derived from the neural folds. In the head, it forms much of the skeleton. It forms dorsal root ganglia, enteric ganglia and pigment cells. 8. Mesoderm develops into notochord, somites, kidneys, gonads, limbs, lateral plate, blood islands, heart and blood vessels during the Xenopus development. 9. On the surface of the dorsal egg cortex egg toward the animal pole and internally components associated with cortex move from a vegetal to a dorsal position..

1. What happens at the mid-blastula transition in Xenopus? Which part of the Xenopus blastula
becomes the mesoderm? Where does the dorsal lip tissue end up when, Xenopus gastrulation is
finished? Where does the vegetal pole end up when gastrulation is finished? How is the central
nervous system formed? Where does the neural crest come from and what does it become?
What are the main tissue types formed from the mesoderm? What happens during the cortical
rotation? What is the principal determinant for endoderm formation in Xenopus? What are the
main mesoderm-inducing factors in Xenopus?
Solution
2. Midblastula transition refers to a number of dramatic changes that occur at this stage in
Xenopus. The important event that happens during this stage is activation of zygotic genes. The
Cell cycle is lengthened, the asynchronous cycle of different cells. Development of cellular
motility.
3. The blastula is composed of three different regions out of which the equatorial or marginal
zone, which compose the walls of the blastocoel differentiate primarily into mesodermal tissue.
4. The lip of the blastopore nearer to the animal pole is termed the dorsal lip of the blastopore.
The dorsal lip of the blastopore forms due to the contraction of bottle cells. It becomes the head
and the dorsal midline structures all along the body. It forms notochord, flanking parts of
somites, floor plate of neural tube.
5. The vegetal plate undergoes primary invagination to produce the archenteron or primitive gut.
Primary invagination is thought to result from changes in the shape of cells in the vegetal plate.
6. During the development, the dorsal ectoderm rolls up into a tube, which becomes the brain at
the anterior end and the spinal cord at the posterior end.
7. The neural crest is a population of migratory cells, derived from the neural folds. In the head,
it forms much of the skeleton. It forms dorsal root ganglia, enteric ganglia and pigment cells.
8. Mesoderm develops into notochord, somites, kidneys, gonads, limbs, lateral plate, blood
islands, heart and blood vessels during the Xenopus development.
9. On the surface of the dorsal egg cortex egg toward the animal pole and internally components
associated with cortex move from a vegetal to a dorsal position.