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Flashcards in Embryology Deck (55)
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1
Q

2 differences of chick gastrulation vs. frog (other than being flat)

A
  1. endoderm displaces hypoblast

2. Hensen’s node closes primitive streak to end gastrulation

2
Q

What does the blastocoel form in the adult?

A

Nothing (gets filled up)

3
Q

Compare blastula cells in mesolecithal

A

Asymmetric/different because yolk slows cleavage

4
Q

Describe steps of neurulation

A

Thick dorsal ectoderm = neural plate
Invaginates, neural groove w/folds on sides
Folds fuse, enclosing neural tube
Epidermal ectoderm grows over top

5
Q

Germ layer origin of chorion

A

Ectoderm, somatic hypomere mesoderm

6
Q

Name the 4 major extra-embryonic membranes

A
  1. Yolk sac
  2. Amnion
  3. Chorion
  4. Allantois
7
Q

Blastula formation events

A

Form hollow ball of cells; hole = blastocoel

8
Q

Which organisms have a chorioallantoic placenta?

A

Most eutherian mammals

9
Q

Morula (def)

A

symmetric ball of cells

10
Q

Germ layer origin of allantois

A

Endoderm, splanchnic hypomere mesoderm (from hindgut region)

11
Q

Events of cleavage

A

Short/no growth phase between cell divisions (division while overall embryo maintains size)

12
Q

Major events of organogenesis

A
  • embryo grows, lengthens

- germ layers further differentiate, work in concert to form complex organs

13
Q

Which direction does Koller’s sickle move?

A

posterior to anterior

14
Q

How do extra-embryonic membranes form?

A

Lateral germ layers (ectoderm, hypomere mesoderm, endoderm) form folds, grow around embryo

15
Q

Describe blastodisk of macrolecithal egg from dorsal to ventral

A

epiblast (dorsal, formed first, forms embryo), blastocoel (middle), hypoblast (ventral, forms after, guides cell migration in gastrulation)

16
Q

Where do neural crest cells originate?

A

In neural folds (during neurulation)

17
Q

Animal pole (def)

A

thinner, yolk-less end of blastula/gastrula (top in most diagrams, made of ectoderm)

18
Q

Germ layer origin of notochord?

A

Mesoderm

19
Q

Homoplasty (def)

A

Structures with a similar appearance

20
Q

What does the archenteron become in the adult?

A

Gut (blastopore = anus in deuterostomes)

21
Q

What does the posterior marginal zone in the chick embryo become?

A

Koller’s sickle, then primitive streak

22
Q

Shape of macrolecithal-egg embryo

A

disk

23
Q

What does the neural tube become in adults?

A

Brain: ventricles

Spinal cord: cerebrospinal fluid canal

24
Q

Function of the yolk sac

A

extra-embryonic membrane surrounding yolk, forming vitelline vessels to transport nutrients from yolk to embryo

25
Q

Which vertebrates have a yolk sac placenta?

A

Most methatherian mammals

26
Q

Function of allantois/allantoic membrane

A

Sequester nitrogenous wastes away from the embryo so it doesn’t poison itself

27
Q

Describe epiblast from anterior to posterior

A

Area opaca -> area pellucida (most of the epiblast) -> posterior marginal zone (thicker, becomes Koller’s sickle, then primitive streak)

28
Q

What does the coelomic fold become in the adult?

A

Muscular diaphragm (mammals only)

29
Q

Mesoderm differentiates into…

A

Notochord, Epimere, Mesomere, Hypomere

30
Q

What happens to the hypoblast in the chick embryo?

A

Displaced by endoderm during gastrulation

Hypoblast: lower layer of blastula, directly dorsal to yolk

31
Q

Cells migrate into the blastopore through which analogous structures in the frog and chick embryo?

A

frog: blastopore
chick: primitive streak

32
Q

What does the coelom divide into in all vertebrates? What separates them?

A

Pericardial & pleuroperitoneal cavities; transverse septum

33
Q

Vegetal pole (def)

A

Thicker, yolk-filled end of blastula/gastrula (bottom in most diagrams, made of endoderm)

34
Q

Which direction does Hensen’s node move?

A

anterior to posterior

35
Q

How do metatherian mammals form the embryonic placenta?

A

From yolk sac

36
Q

What is Hensen’s node?

A

Anterior end of the primitive streak

37
Q

Germ layer origin of yolk sac

A

Endoderm, splanchnic hypomere mesoderm

38
Q

How do complex organs form in the embryo?

A

Several germ layers work together

39
Q

Which organisms do/don’t have an allantois & why?

A

Anamniotes: no, wastes diffuse into water
Mammals: no, wastes removed by placenta
Sauropsids: yes, can’t get rid of wastes

40
Q

Germ layer origin of amnion

A

Ectoderm, somatic hypomere mesoderm

41
Q

Ectoderm differentiates into…

A

Neural crest cells, neural plate cells, Epidermal

42
Q

Epimere mesoderm forms… In the 24-hour chick embryo (overall structure name, plus differentiated layers)

A

somites (little balls); dermatome, myotome, sclerotome

43
Q

What does the pleuroperitoneal cavity divide into in mammals, and what separates it?

A

Pleural cavity, peritoneal cavity; coelomic fold (becomes muscular -> diaphragm)

44
Q

What is contained in the amnion?

A

Embryo, amniotic fluid

45
Q

Who has protostome development?

A

Invertebrates: arthropods, molluscs, insects, etc.

46
Q

How do eutherian mammals form the placenta?

A

From chorioallantoic membrane

47
Q

3 main events of gastrulation

A
  1. archenteron formation by cell migration into blastocoel
  2. germ layer differentiation
  3. committed anterior/posterior
48
Q

Function of amnion

A

Cushion embryo in amniotic fluid, prevent dessication (b/c waterproof)

49
Q

What is the transverse septum & what does it do?

A

Fold that divides coelom into pericardial & pleuroperitoneal cavities

50
Q

Function of placenta

A

Exchange gases, nutrients, wastes between mother & embryo

51
Q

Where is the coelom located?

A

Between the somatic and splanchnic hypomere mesoderm

52
Q

3 differences between deuterostomes & protostomes

A
  1. Cleavage pattern (spiral in protostomes, radial in deuterostomes)
  2. End function of blastopore (mouth in protostomes, anus in deuterostomes)
  3. Origin of skeleton (protostomes: ectoderm mostly, deuterostomes: mesoderm mostly)
53
Q

How is the primitive streak formed?

A

Migration of Koller’s sickle from posterior to anterior (mnemonic: sickle cuts up to form streak)

54
Q

Describe structure & function of chorion

A

Membrane fuses w/allantois to form chorioallantoic membrane; allows gas exchange through egg shell via many blood vessels

55
Q

What is the coelomic fold and what does it do?

A

Divides pleuroperitoneal cavity in mammals into pleural and peritoneal cavities by fusing with transverse septum