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Flashcards in Embryology Deck (23):
1

Describe the stages of early human embryonic development that generate the 3 primary embryonic germ layers

endo-, meso-, and ectoderm all derive from the epiblast
The epiblast cells migrate to midline at caudal end of embryo
--forms thickened band called the primitive streak
--streaks elongate cranially
--cranial tip forms called the primitive node
cells from primitive streak and node migrate downward-
--create mesoderm which fills space between epi and hypoblast
--displace hypoblast to form endoderm; hypoblast cells then migrate to cover blastocyst cavity to form yolk sac
--cells that don't migrate form the ectoderm

2

Describe placenta formation and some basic functions during fetal development

Trophoblast burrow into uterine wall; uninucleate trophoblast push down into polynucleate trophoblast to form microvilli which contain embryonic vessels; the villi + associated endometrium = placenta

3

Describe the formation and functions of the amnion and embryonic yolk sac

Amnion--cavity formed by above epiblast cells by epiblast cells; fills with fluid and surrounds embryo

4

Discuss the origins of the 3 types of mesoderm

Paraxial Mesoderm – along midline – forms somites
Para = beside, paraxial= beside axis, runs right beside notochord
Paraxial mesoderm = somites, same thing, named differently
Lateral Plate Mesoderm – extends laterally – forms serous membranes of body wall cavities, bones of appendicular skeleton
Intermediate Mesoderm – between Paraxial and Lateral Mesoderm – forms urogenital structures and gonads

5

Describe the process of somite formation and differentiation and summarize the structures that somites will give rise to

ninin

6

Discuss clinical correlations associated with early development

bbhj

7

What does the inner cell mass of the morula produce?

embryo proper

8

what does the outer cell mass of the morula produce?

trophoblast--placenta and responsible for implantation

9

How long does it take to form a blastocyst?

5 days

10

where does an egg normally implant in the uterus?

Anterior or posterior wall--though all spaces (including lateral and medial)

11

where does an egg normally implant in the uterus?

Anterior or posterior wall--though all spaces (including lateral and medial)

12

what cell is responsible for producing hCG?

trophoblasts

13

what forms lacunae?

trophoblasts

14

syncytiotrophoblast are multinucleate

yes

15

how long does it take to detect hCG?

one-two weeks after fertilization

16

why can hCG be detected in urine?

due to mother/fetal exchange via uterine capillaries/lacunae

17

What does the inner cell mass form?

epiblast--forms all tissue of embryo and lining of newly developing amniotic sac
hypoblast--will form yolk sac

18

what is the bilaminar disk?

the two layers epi- and hypoblast squished on top of each other?

19

list the ectodermal derivatives

Epidermis, Brain and Spinal cord, Peripheral Nervous System, Autonomic Nervous System, Skull

20

list the mesodermal derivatives

Skeletal muscles, Heart and Blood vessels, Kidneys and Gonads, Skeleton and most Connective Tissues

21

List the endodermal derivatives:

Inner lining of gut tubes, respiratory tracts, bladder and some GI organs

22

what is the most important job of the notochord?

to induce cells to differentiate to form the CNS

23

Lateral Plate Mesoderm
Lateral edge of embryo
Cavitates to form two layers:
Somatic (parietal) Layer – with embryonic folding ends up along body wall of embryo under ectoderm – forms many structures of body wall and limbs
Splanchnic (visceral) Layer – with folding ends wrapping around part of yolk sac that gets incorporated into body cavity – forms serous layers around organs

ye