Topic 17: Development II Flashcards Preview

Biology 116 > Topic 17: Development II > Flashcards

Flashcards in Topic 17: Development II Deck (29):
1

What happens after cleavage?

normal cell cycle resumes
cell division slows
animal body starts to take shape during next 2 stages of development:
- gastrulation
- organogenesis

2

What is gastrulation?

morphological process by which hollow blastula becomes layered embryo (gastrula) with:
- a digestive tube
- embryonic germ layers

3

What are the steps to gastrulation in sea urchins?

1. mesenchyme cells at vegetal pole migrate into blastocoel
2. invagination at vegetal pole
3. archenteron forms
4. archenteron extends across blastocoel
5. mouth formation

4

What is invagination?

when the cells of the vegetal plate flatten and buckle and fold inward

5

What are filopodia?

mesenchyme cells produce this at tip; they are thin extensions

6

What are the steps to gastrulation in birds?

1. formation of epiblast and hypoblast
2. formation of primitive streak
3. formation of 3 germ layers

7

What is a trophoblast?

outer single layer of cells

8

What is the inner cell mass?

the cluster of cells that become an embryo

9

What are the steps to gastrulation in humans?

1. implantation
2. formation of epiblast and hypoblast
3. formation of 4 extraembryonic membranes
4. formation of 3 germ layers

10

What is organogenesis?

process of organ formation

11

What is neurulation?

formation of the brain and spine

12

What forms the notochord?

mesoderm

13

What forms the nerve cord?

ectoderm

14

What is induction?

the process by which cells stimulate or influence differentiation of neighboring cells

15

What are the steps in neurulation?

1. formation of the notochord
2. formation of neural plate
3. formation of neural tube

16

How does the neural plate form?

the notochord induces the ectoderm above it to thickem

17

How does the neural tube form?

the neural plate rolls up

18

What does the neural tube develop into?

the CNS
anterior portion -> brain
remainder -> spinal cord

19

What happens to the notochord?

most of it disappears, some form vertebral discs

20

Why does spina bifida happen?

it occurs when the neural tube doesn't form properly

21

What is the neural crest?

it's between the neural tube and ectoderm
cells migrate -> nerves, teeth, skull, bones

22

What are somites? What do they do?

blocks of mesoderm cells next to notochord
migrate -> segmented/repeated structures - ribs, vertebrae, muscless

23

What happens during the first trimester?

the biggest changes for the mother and embryo
the implanted embryo secretes hCG and acts like LH on corpus luteum - maintains progesterone, estrogen secretion

24

How does the placenta form?

when first implanted, the nutrients come directly from the endometrium
weeks 2-4 the triploblast mixes with endometrium to form the placenta

25

What is the placenta?

an organ of exchange between mother and embryo - exchanges nutrients, gases, immunity, waste

26

What connects the embryo to placenta?

the umbilical cord

27

Identical vs fraternal twins

identical twins come from the same egg and sperm
fraternal twins come from 2 different eggs and sperms

28

What happens during birth?

it begins with labor, then
uterine contractions to push the fetus and placenta out
it is regulated by prostaglandins, hormone like estradiol and oxytocin

29

What are the stages of birth?

1. dilation of cervix
2. explusion: delivery of the infant
3. delivery of the placenta