Lecture 1

Question 1

stages in development

Answer 1

-gametogenesis
-fertilization
-cleavage
-gastrulation
-organogenesis
-hatching (birth)
-larval stages
-metamorphosis (in some species)
-maturity

Question 2

what processes control the elaboration of cell- and tissue- type patterns?

Answer 2

morphogenesis

Question 3

how can growth, migration, and death of individual cells be directed and coordinated to organize into complex functional structures?

Question 4

during development, cells ___, ___, and ___; tissues ___ and ___

Answer 4

divide, migrate, and die
fold and separate

Question 5

what are the developmental mechanisms controlling sexual determination?

Answer 5

gametogenesis, fertilization and early development

Question 6

how does the environment influence developmental processes to generate phenotypic (morphological) variation?

Answer 6

diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all affect which genes are expressed

Question 7

how do changes in development create new body forms?

Question 8

which heritable changes are possible, given the constraints imposed by the necessity of the organism to survive as it develops?

Question 9

Invagination

Answer 9

infolding of a sheet (epithelium) of cells, much like the indention of a soft rubber ball when it is poked

Question 10

involution

Answer 10

inward movement of an expanding outer layer so that it spreads over the internal surface of the remaining external cells

Question 11

ingression

Answer 11

migration of individual cells from the surface into the embryo’s interior. individual cells become mensechymal (separate from one another) and migrate independently

Question 12

delamination

Answer 12

splitting of one cellular sheet into two more or less parallel sheets. while on a cellular basis it resembles ingression, the result is the formation of a new (additional) epithelial sheet of cells

Question 13

epiboly

Answer 13

movement of epithelial sheets (usually ectodermal cells), spreading as a unit (rather than individually) to enclose deeper layers of the embryo. can occur by cells dividing, by cells changing their shape, or by several layers of cells radially intercalating into fewer layers (arrows)

Question 14

convergent extension

Answer 14

movement of more lateral cells of all germ layers toward the midline. This leads to a convergence of those cells causing their intercalation along the medial to lateral axis. As these cells converge en masse, the embryo extends along the anterior-to-posterior axis