DevBio Exam 2 questions with complete
questions and answers { graded a+}
Epiboly - ✔✔the movement of epithelial sheets (usually ectodermal
cells) that spread as a unit (rather than individually) to enclose the
deeper layers of the embryo.
What are 3 mechanisms in which epiboly can occur? - ✔✔1. by cells
dividing
2. by cells changing shape
3. by several layers of cells intercalating into fewer layers
Give 3 reasons why zebrafish are good models to study development. -
✔✔1. brood size
2. external fertilization/development
, 3. transparent embryos
What type of cleavage does the zebrafish embryo undergo during early
development? - ✔✔discoidal meroblastic cleavage
What is discoidal cleavage? - ✔✔A meroblastic cleavage pattern for
telolecithal eggs, in which cell divisions occur only in the small
blastodisc
i.e. birds, reptiles, fish
ZF (zebrafish) Yolk Syncytial Layer (YSL) - ✔✔constructs mesoderm
produces fish organizer
helps ectoderm undergo epiboly
ZF Deep cells - ✔✔located in b/w enveloping layer & yolk syncytial layer
give rise to embryo proper
considered 3rd set of blastomeres
questions and answers { graded a+}
Epiboly - ✔✔the movement of epithelial sheets (usually ectodermal
cells) that spread as a unit (rather than individually) to enclose the
deeper layers of the embryo.
What are 3 mechanisms in which epiboly can occur? - ✔✔1. by cells
dividing
2. by cells changing shape
3. by several layers of cells intercalating into fewer layers
Give 3 reasons why zebrafish are good models to study development. -
✔✔1. brood size
2. external fertilization/development
, 3. transparent embryos
What type of cleavage does the zebrafish embryo undergo during early
development? - ✔✔discoidal meroblastic cleavage
What is discoidal cleavage? - ✔✔A meroblastic cleavage pattern for
telolecithal eggs, in which cell divisions occur only in the small
blastodisc
i.e. birds, reptiles, fish
ZF (zebrafish) Yolk Syncytial Layer (YSL) - ✔✔constructs mesoderm
produces fish organizer
helps ectoderm undergo epiboly
ZF Deep cells - ✔✔located in b/w enveloping layer & yolk syncytial layer
give rise to embryo proper
considered 3rd set of blastomeres
