3.3 lecture - embryology - development of body plan - MacNeil Flashcards Preview

COT 1 (WPH) > 3.3 lecture - embryology - development of body plan - MacNeil > Flashcards

Flashcards in 3.3 lecture - embryology - development of body plan - MacNeil Deck (80)
1

which conceptus layer is always adjacent to maternal blood supply?

syncytiotrophoblast

2

where is the chorionic cavity in relation to the yolk sac and the amnionic cavity?

chorionic is outside surrounding both yolk sac and amnionic cavity. the chorion is connected to the embryo via the connecting stalk (becomes umbilical cord)

3

what layers are present in each primary villus extending from the chorion into the decidua? secondary villus?
tertiary villus?

-primary - syncytiotrophoblast and cytotrophoblast
-secondary - syncitiotrophoblast, cytotrophoblast, mesoderm core
-tertiary - synciciotrophoblast, cytotrophoblast, mesoderm core, villous capillaries within mesoderm core

4

why is week 3 of embryo development the "week of threes" ?

3 cavities - chroionic, definitive yolk sac, amnionic
3 placental layers - syncytiotrophoblast, cytotrophoblast, extraembryonic mesoderm
3 germ layers - ecto, meso, endoderm
3 body axes - craniocaudal, dorsoventral, R/L

5

function of the:
-amnion
-yolk sac

amnion - line fluid filled amnionic cavity
yolk sac - transfer agent for nutrients, site of primordial germ cells, source of blood cells and blood vessels

6

epiblast cells that migrate through the primitive groove and migrate cranially in the mesoderm along the cranial caudal axis will form the __

notochord

7

what cells is the notochord derived from?

epiblast cells that migrate through the primitive groove and migrate cranially in the mesoderm along the cranial caudal axis

8

what germ layer is the notochord derived from?

mesothelium

9

another name for the notochord is the...

axial mesoderm

10

the notochord is important for 3 reasons:

-signals induction of neural tube, somites, and surrounding structures
-vertebral column and base of skull develop around it
-degenerates to leave behind nucleus pulposus of the intervertebral disc

11

this structure signals the induction of the neural tube, somites, and surrounding structures

notochord

12

the vertebral column and base of the skull develop around this structure

notochord

13

this structure ultimately degenerates to leave behind nucleus pulposus of the intervertebral discs in adults

notochord

14

the location and function of the nucleus pulposus

-located in center of intervertebral discs in adults
-jelly-like structure that functions to distribute compressive loads through hydraulic pressure

15

T/F during gastrulation, the cells in the ectoderm that will ultimately form the heart migrate to just below the oropharyngeal membrane

false - the heart will be derived from cells of the Mesoderm that migrate Above the oropharyngeal membrane during gastrulation (this cranial end will ultimately fold over so these heart deriving cells are located caudally to oropharyngeal membrane)

16

what 2 germ layers are fused at the oropharyngeal and cloacal membranes?

ectoderm and endoderm are fused (no mesoderm)

17

~ what day do the oropharyngeal and cloacal membranes break down?

~ day 26

18

a solid cord of cells that underlies the developing neural tube forming a midline axis and serves as a basis for the axial skeleton. induces the neural plate and sclerotome portion of the somite

notochord

19

describe 7 key structures in the sequence in which they arise in the process of neurulation

-neural plate
-axial neural groove / neural folds
-neural crests
-neural tube
-neural crest cells
-primitive brain
-primitive spinal cord

20

neurulation is...

the process by which the neural tube forms

21

neurulation begins on day __

day 18

22

when the notochord thickens and expands mitotically it forms the...

neural plate

23

folding of the neural plate gives rise to these 2 structures

-axial neural groove
-neural crests

24

this is where the neuroectoderm merges with the somatic ectoderm during neurulation

neural crests

25

fusion of neural folds in neurulation results in the formation of...

the neural tube

26

neural crest cells arise when...

around the time of neural fold fusion to form the neural tube during neurulation, the neural crests detach from the neural tube and migrate into the mesoderm layer

27

the neural crests detach from the neural tube and migrate into the mesoderm to become...

neural crest cells

28

describe the fusion that gives rise to the neural tube

-neural folds approach each other
-somatic ectoderm fuses at surface (beginning somewhere mid-axial and zipping up cranially and down caudally)
-neural crest cells detach, migrate into paraxial mesoderm
-neural tube sinks into mesoderm layer
-neural tube folds ventrally to close tube

29

neural crest cell detachment and migration into mesoderm during gastrulation is an example of what kind of transition?

epithelial to mesenchymal transition

30

mesenchyme is..

embryonic connective tissue in the mesoderm

31

T/F fusion of neural folds is due to genetic factors (genes such as sonic hedgehog) and environmental factors (cholesterol and folic acid)

true

32

what day does closure of the neural tube at each neuropore occur?

Anterior/cranial neuropore: ~day 25
Posterior/caudal neuropore: ~day 28

33

name the four subdivisions of neural crest derivatives

-cranial
-cardiac
-vagal
-trunk

34

examples of neural crest derivatives include:

-connective tissue of bones, neck, face skull
-cranial nerve ganglia
-heart septum (cavity wall enclosing heart)
-dentin of tooth
-dermis of head and neck
-dorsal root ganglia
-enteric nervous system
-sympatheitic chain
-adrenal medulla
-Schwann cells (myelin forming cells in PNS)
-glial cells
-malanocytes of skin
-smooth muscle of head region blood vessels

35

the following are examples of derivatives of what 3rd week structure?
-connective tissue of bones, neck, face skull
-cranial nerve ganglia
-heart septum (cavity wall enclosing heart)
-dentin of tooth
-dermis of head and neck
-dorsal root ganglia
-enteric nervous system
-sympatheitic chain
-adrenal medulla
-Schwann cells (myelin forming cells in PNS)
-glial cells
-malanocytes of skin
-smooth muscle of head region blood vessels

derivatives of neural crest cells

36

what are the 2 types of ectoderm in week 3 of development

-neuroectoderm
-surface ectoderm

37

name some derivatives of the surface ectoderm

• epidermis
• nails
• hair
• subcutaneous glands
• mammary glands
• anterior pituitary
• enamel
• lens of the eye

38

name some derivatives of the neuroectoderm

• central nervous system
• retina
• posterior pituitary gland
• pineal body

39

the following are all derivatives of what 3rd week structure?
• epidermis
• nails
• hair
• subcutaneous glands
• mammary glands
• anterior pituitary
• enamel
• lens of the eye

surface ectoderm

40

the following are all derivatives of what 3rd week structure?
• central nervous system
• retina
• posterior pituitary gland
• pineal body

neuroectoderm

41

what are 2 key regions of the axial mesoderm and why are they important

-cardiogenic mesoderm - at cranial end of embryo, forms heart tubes
-axial rod of mesoderm - forms notochord, which strongly influences formation of nervous system and vertebral column

42

what is the importance of the cardiogenic mesoderm?

it is the part of the axial mesoderm that forms the heart tubes at cranial and of embryo

43

what is the importance of the axial rod of the mesoderm?

forms notochord, which strongly influences formation of nervous system and vertebral column

44

from medial to lateral, what are 4 key longitudinal regions of the mesoderm and what do they give rise to?

-axial mesoderm (heart tubes, notochord)
-paraxial mesoderm (somites)
-intermediate mesoderm (urogenital system)
-lateral plate mesoderm (coelum, viscera)

45

what does the paraxial mesoderm give rise to?

somites

46

what does the intermediate mesoderm give rise to?

urogenital system

47

what does the lateral plate mesoderm give rise to?

-coelum (body cavity)
-connective tissue and muscle of the viscera
-serous membranes

48

what does the coelum refer to?

the body cavity

49

what does the viscera refer to?

the internal organs in the main cavities of the body, esp. those in the abdomen, e.g., the intestines

50

what cells undergo ectodermal to mesenchymal differentiation during neurulation?

neural plate cells

51

which longitudinal region of the mesoderm is continuous with the extraembryonic mesoderm covering the yolk sac and amnion?

lateral mesoderm

52

where do first somites arise from the paraxial mesoderm?

in the occipital region

53

in what kind of sequence to new somites develop from the paraxial mesoderm? until how many somites?

-from cranial to caudal
-until 42 pairs of somites

54

how is the paraxial mesoderm correlated to age of the embryo during week 3 of development?

age is correlated to the number of somite pairs present

55

from inner to outer, what 3 structures does each somite form?

-sclerotome -> bone (axial skeleton)
-myotome -> muscle (skeletal muscle)
-dermatome -> connective tissue (dermis of skin)

56

what is a scleratome derived from and what does it give rise to?

-from somite (from paraxial mesoderm)
-creates axial skeleton (vertebrae, ribs, occipital bone of skull)

57

what is a myotome derived from and what does it give rise to?

-from somite (from paraxial mesoderm)
-creates skeletal muscle of body, head/neck, and limbs

58

what is a dermatome derived from and what does it give rise to?

-from somite (from paraxial mesoderm)
-contributes to dermis of skin (connective tissue layer of skin)

59

what is a key component that migrates with each sclerotome, myotome, and dermatome derived from a somite?

each has its own segmental nerve component migrating with the developing cells

60

somites and their developing sclerotomes, myotomes, and dermatomes can be classed into what 4 groups?

-occipital
-cervical
-thoracic
-lumbar

61

what is a dermatomal pattern

area of skin supplied by a single spinal nerve

62

what happens to the lateral mesoderm in the trunk ~day 17 of development

develops clefts that eventually split it into two layers associated with the endoderm and ectoderm, and the space between the two layers
-splanchnic mesoderm - mesothelial coverings (gut wall)
-somatic mesoderm - (body wall)
-intraembryonic coelum - primitive body cavity

63

splanchnic mesoderm

formed from the splitting of the lateral mesoderm in the trunk ~day 17, associated with endoderm,, gives rise to mesothelial coverings

64

intraembryonic coelum

primitive body cavity formed from the splitting of the lateral mesoderm in the trunk into splanchnic mesoderm and somatic mesoderm

65

what organ system develops from the intermediate mesoderm

urinary & reproductive systems

66

what is the intermediate mesoderm

in 2-3 week embryo, intermediate mesoderm is mesodermal layer between lateral mesoderm (which is splitting into somatic and splanchnic mesoderms) and the somites / neural tube
-develops into the urinary & reproductive systems

67

as folding of the intraembryonic coleum forms a horseshoe pointing up, where is the...
-pericardial cavity
-pleural cavity
-peritoneal cavity

-pericardial cavity - bottom of horseshoe ring
-pleural cavity - lateral extensions
-peritoneal cavity - lateral extensions

68

summarize week 3 development formations

-gastrulation
-major body axes
-notochord
-primordial nervous system (neural tube)
-somites
-cardiogenic area
-primordial body cavity
(still flat trilaminar disk)

69

summarize completion of embryonic period (weeks 4-8)

morphogenesis
organogenesis
body folding

70

in what week of development does body folding initiate?

week 4

71

in embryonic body folding, the oropharyngeal membrane, cardiogenic area, pericardial cavity, and septum transversum (contributes to diaphragm) are relocated to their appropriate positions by what folding process

head folding

72

in embryonic folding, the cloacal membrane, connecting stalk, and hindgut are relocated to their appropriate positions by what folding process

tail folding

73

what causes head folding?

differential growth at the neural plate

74

what causes tail folding?

growth of spinal cord

75

what causes lateral folding?

growth of somites

76

as abdominal wall form through lateral folding, part of the endoderm of the yolk sac is incorporated into the embryo as the __

midgut

77

what is the yolk stalk

connects midgut (part of yolk sac incorporated into body cavity as lateral folding occurs) to yolk sac (hangs outside folding until abdominal wall closes and disconnects yolk sac

78

3 body cavities in adults

pleural
pericardial
peritoneal

79

T/F the connecting stalk, which becomes the umbilical cord, is an extension of the yolk sac

false
it is an extension of the chorion

80

at the end of body folding in the embryonic period, the entire embryo is surrounded by the __, which is itself surrounded by the __

amnionic fluid and amnion
chorionic fluid and chorion