DevBio Exam 2 questions with complete questions and answers { graded a+}

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