Intro 30: Derivatives of endoderm and pharyngeal arches Flashcards

1
Q

ENDODERM gives rise to…

A

EPITHELIAL lining of various body parts

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2
Q

WEEK 3, during GASTRULATION
and EARLY SOMITE DEVELOPMENT, what do we get of the FOREGUT, MIDGUT, HINDGUT

A

patterning of the ENDODERM into FOREGUT, MIDGUT, HINDGUT PROGENITOR DOMAINS
- future sits of foregut, midgut, hindgut are determined

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3
Q

as a result of EMBRYO FOLDING in WEEK 4..

A

FOREGUT and HINDGUT POCKETS FORM
- as the ENDODERMAL CUP is transformed into a GUT TUBE

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4
Q

what happens to the MIDGUT as foregut and hindgut pockets form during week 4?

A

MIDGUT remains in contact with the YOLK SAC until it DEGENERATES much LATER

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5
Q

ENDODERMAL SPROUTING results in the formation of what in the FOREGUT

A

UPPER SECTION of foregut:
primordial
- THYROID
- THYMUS
- LUNGS (lung bud)

LOWER SECTION of foregut:
primordial
- LIVER (liver bud)
- PANCREAS

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6
Q

when do we get development of the LIVER PRIMORDIUM / LIVER BUD

A

MIDDLE of 3RD WEEK

  • appears as an outgrowth of
    the ENDODERMAL EPITHELIUM at the distal end of the foregut
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7
Q

what plays a crucial role in INDUCTION of LIVER PROGENITOR CELLS (HEPATOBLASTS)

A

CARDIOGENIC MESODERM

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8
Q

what plays a crucial role in INDUCTION of LIVER PROGENITOR CELLS (HEPATOBLASTS)

A

CARDIOGENIC MESODERM

by providing extracellular signals

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9
Q

LIVER BUD CELLS differentiate into

A

PARENCHYMA (HEPATOCYTES)

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10
Q

haematopoietic cells, Kupffer cells and
connective tissue cells are derived from

A

MESODERM

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11
Q

Majority of the LIVER is derived from which germ layer

A

ENDODERM

but some from MESODERM (hepatic mesenchyme)

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12
Q

the PANCREAS is formed from 2 BUDS:

A
  • DORSAL PANCREATIC BUD
  • VENTRAL PANCREATIC BUD
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13
Q

the PANCREATIC BUDS (dorsal, ventral) originate from the ENDODERMAL LINING of the…

A

DUODENUM

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14
Q

which PANCREATIC BUD forms the UNCINATE PROCESS

A

VENTRAL PANCREATIC BUD

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15
Q

the VENTRAL pancreatic bud forms… (2)

A
  • the UNCINATE PROCESS
  • the VENTRAL PANCREAS / inferior part of the head of the pancreas

the rest of the pancreas is derived from the DORSAL PANCREATIC BUD

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16
Q

when do the pancreatic ISLETS OF LANGERHANS develop

A

3RD MONTH of embryonic development

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17
Q

when does INSULIN secretion begin

A

5TH MONTH

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18
Q

when does development of the RESPIRATORY DIVERTICULUM (LUNG BUD) take place

A

approx 4 WEEKS

  • develops as an outgrowth from the
    VENTRAL WALL of the foregut
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19
Q

Which parts of the RESPIRATORY SYSTEMare of ENDODERMAL origin

A

Epithelium of the internal lining of the larynx,
trachea,
bronchi
lungs

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20
Q

cartilaginous, muscular and connective tissue components of the trachea and lungs are derived from..

A

SPLANCHNIC MESODERM surrounding foregut

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21
Q

Lung bud EXPANDS CRANIALLY and 2 ridges appear and fuse:

A

TRACHEOESOPHAGEAL RIDGES

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22
Q

when TRACHEOESOPHAGEAL RIDGES FUSE what is formed

A

TRACHEOEPHAGEAL SEPTUM

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23
Q

TRACHEOEOPHAGEAL SEPTUM DIVIDES FOREGUT into :

A

Dorsal:
OESOPHAGUS

Ventral:
TRACHEA
& LUNG BUDS

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24
Q

4 stages of lung maturation:

A
  • Pseudoglandular Period (6-16 weeks)
  • Canalicular Period (16-26 weeks)
  • Terminal Saccular Period (26 weeks to birth)
  • Alveolar period (32 weeks to 8 years)
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25
Q

DERIVATIVES of the ENDODERM

A
  • Digestive tract
  • Epithelial lining of the respiratory tract
  • Essential tissues of the thyroid, parathyroid, liver and pancreas
  • Connective tissues of thymus and tonsils
  • Epithelial lining of urinary bladder, urethra, tympanic membrane and auditory tube
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26
Q

Until the end of the 4th week,
the NEURAL TUBE is…

A

OPENED at the cranial and caudal NEUROPORES

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27
Q

BY DAY 24,
what appears as a result of EMBRYO GROWTH and FOLDING

A

PHARYNGEAL ARCHES appear
(arch-shaped FOLDS in the throat area)

due to rapid growth, the 3rd and 4th pharyngeal arches appear by day 28

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28
Q

How many PHARYNGEAL ARCHES are there in humans:

A

5

1,2,3,4 and 6 SIX

(no. 5 regresses almost immediately)

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29
Q

what is the name of PHARYNGEAL ARCH 1

A

MANDIBULAR ARCH

has 2 prominences:
- MAXILLARY 1
- MANDIBULAR 1

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30
Q

Which two PHARYNGEAL ARCHES FUSE

A

4 and 6

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31
Q

what is the name of PHARYNGEAL ARCH 2 and what does it do

A

HYOID ARCH

-forms most of HYOID BONE

32
Q

What do PHARYNGEAL ARCHES 3 and 4 (fuses with 6) FORM

A

NECK STRUCTURES

33
Q

Each PHARYNGEAL ARCH consists of

A
  • CORE of MESENCHYME (MESODERM)
  • ECTODERM (outside)
  • ENDODERM (inside)
34
Q

what does each PHARYNGEAL ARCH contain

A
  • BLOOD VESSEL
  • CARTILAGE
  • MUSCULAR component
  • NERVE
35
Q

what innervate PHARYNGEAL ARCHES

A

cranial nerves

36
Q

PA 1
aortic arch remnant?
which cranial nerve innervates it?
derivatives?

A
  • Maxillary Artery
  • Trigeminal Nerve
  • muscles of mastication
  • Meckel’s cartilage,maxilla, palatine bone, squamous temporal bone
37
Q

PA 2
aortic arch remnant?
which cranial nerve innervates it?
derivatives?

A
  • Stapedial and Hyoid Arteries
  • Facial Nerve
  • muscles of facial expression
  • Reichert’s cartilage …lesser horn of hyoid
38
Q

PA 3
aortic arch remnant?
which cranial nerve innervates it?
derivatives?

A

-common and internal Carotid Arteries

  • Glossopharyngeal Nerve
  • Stylopharyngeus
  • Greater horn and inferior body of Hyoid Bone
39
Q

PA 4
aortic arch remnant?
which cranial nerve innervates it?
derivatives?

A

-Arch of Aorta, right Subclavian artery

  • Vagus nerve
  • Pharyngeal and Palatal Muscles
  • Thyroid Cartilage
40
Q

PA 6
aortic arch remnant?
which cranial nerve innervates it?
derivatives?

A
  • Ductus Arteriosus, Pulmonary arteries
  • Vagus nerve
  • most intrinsic muscles of Larynx
  • Cricoid cartilage
41
Q

what are also formed during PHARYNGEAL ARCH DEVELOPMENT

A

PHARYNGEAL CLEFTS AND POUCHES

pouches - structures in between arches
clefts- opposite pouches

THESE GIVE RISE TO IMPORTANT STRUCTURES

42
Q

Abnormalities associated with
development of pharyngeal arches
EXAMPLES

A

TREACHER-COLLINS SYNDROME
(mandibulofacial dyostosis)
- Autosomal dominant
- 1/10,000 –1/50,000
- No ossification, no development of
MANDIBLE
- Mandibular and malar hypoplasia
- Abnormal external, middle and inner
ear (conductive hearing loss)
- Lower eyelid defects

PIERRE ROBIN SEQUENCE
- Likely autosomal dominant
- 1/4,000 –1/10,000 live births
- Triad of orofacial morphological
anomalies: micrognathia, retrognathia,
glossoptosis and a posterior median
velopalatal cleft (U-shaped)

DI-GEORGE SYNDROME
- Autosomal dominant
- 1/4,000 live births
- Caused by DELETION of small segment
of CHROMOSOME 22 –CATCH22
- Cardiac abnormality
- Abnormal facies
- Thymic aplasia (infections)
- Cleft palate
- Hypocalcemia/Hypoparathyroidism

43
Q

At 23 DAYS (week 4)

A
  • Neural folds have fused to form the
    NEURAL TUBE (primordium of the spinal
    cord in this region)
  • The neural tube is still OPENED at the
    cranial and caudal ends and
    communicates with the amniotic cavity
    via cranial (rostral or anterior) and
    caudal (posterior) neuropores
  • 10-somite embryo
43
Q

At 23 DAYS (week 4)

A
  • Neural folds have fused to form the
    NEURAL TUBE (primordium of the spinal
    cord in this region)
  • The neural tube is still OPENED at the
    cranial and caudal ends and
    communicates with the amniotic cavity
    via cranial (rostral or anterior) and
    caudal (posterior) neuropores
  • 10-somite embryo
44
Q

At DAY 23 (week 4)

A
  • Neural folds have fused to form the
    NEURAL TUBE (primordium of the spinal
    cord in this region)
  • The neural tube is still OPENED at the
    cranial and caudal ends and
    communicates with the amniotic cavity
    via cranial (rostral or anterior) and
    caudal (posterior) neuropores
  • 10-SOMITE embryo
45
Q

at DAY 24 (week 4)

A
  • The rostral / CRANIAL NEUROPORE is CLOSING, but the
    CAUDAL NEUROPORE is still OPEN
  • The embryo is starting to CURVE because of FOLDING of the cranial and caudal ends
  • 13-SOMITE embryo
46
Q

at DAY 26 (week 4)

A
  • The embryo is very CURVED with prominent tail-like CAUDAL EMINENCE
  • 27-SOMITE embryo
  • The LENS PLACODE is the primordium of the lens of the eye
  • The ROSTAL NEUROPORE is CLOSED (caudal open)
  • 3 PAIRS of PHARYNGEAL ARCHES are present
  • The PRIMORDIAL HEART produces a large ventral prominence and PUMPS BLOOD
47
Q

at DAY 28 (week 4)

A
  • The primordial heart is large and
    divided into a PRIMORDIAL ATRIUM and
    VENTRICLE
  • Both rostral and caudal NEUROPORES
    are CLOSED
  • The embryo has a characteristic C-SHAPED curvature (due to folding)
  • UPPER and LOWER LIMB BUDS are
    visible

-4 PAIRS of PHARYNGEAL ARCHES are
present

48
Q

at WEEK 5 - day 32

A
  • Rapid development of the BRAIN and
    FACIAL PROMINENCES, face contacts the
    heart prominences (really curved)
  • The MESONEPHRIC RIDGES indicate the SITE OF MESONEPHRIC KIDNEYS, an interim functional kidney
  • The UPPER LIMB BUDS are PADDLE-SHAPED, whilst the LOWER LIMB BUDS
    are FLIPPER-LIKE
49
Q

WEEK 6 - day 42

A
  • The DIGITAL RAYS (primordia of the
    digits - fingers/toes) begin to develop
  • The AURICULAR HILLOCKS develop and
    CONTRIBUTE to the formation of auricule
    (EXTERNAL EAR)
  • RETINAL PIGMENT is visible (where eyes would be)
  • The embryo shows SPONTANEOUS MOVEMENTS and RESPONSES TO TOUCH
50
Q

WEEK 8 - day 56

A
  • At the beginning of the eight week the
    DIGITS of the hand and feet are separated,
    but still webbed; by the END OF THE WEEK DIGITS have lengthened and SEPARATED
  • The SCALP VASCULAR PLEXUS appears
  • COORDINATED LIMB MOVEMENTS occur for the first time
  • PRIMARY OSSIFICATION begins in FEMUR
  • At the end of the eight week the embryo
    has VISUALLY DISTINCT HUMAN CHARACTERISTICS
51
Q

when are both rostral and caudal NEUROPORES CLOSED

A

DAY 28 of week 4

52
Q

when do we get MESONEPHRIC RIDGES, which mark the site of mesonephric kidneys

A

WEEK 5 - DAY 32

53
Q

When is the embryo very CURVED with a CAUDIAL EMINENCE

A

DAY 26 of week 4

  • starts curving at day 24
54
Q

how many pairs of PHARYNGEAL ARCHES are present at DAY 26 (week4)

A

3 PAIRS

55
Q

how many pairs of PHARYNGEAL ARCHES are present at DAY 28 (week4)

A

4 PAIRS

56
Q

when is the PRIMORDIAL HEART present and PUMPING BLOOD

A

DAY 26 of week 4

57
Q

when does the PRIMORDIAL HEART divide into ATRIUM and VENTRICLE

A

DAY 28 of week 4

58
Q

When is the first COORDINATED LIMB MOVEMENT

A

WEEK 8 (day 56)

59
Q

when does the embryo show SPONTANEOUS MOVEMENTS and RESPONSES to TOUCH

A

WEEK 6 (day 42)

60
Q

when is the NEURAL TUBE formed (by fusion of neural folds)

A

DAY 23 of week 4

61
Q

how many SOMITEs present at DAY 23 (week 4)

A

10 SOMITE EMBRYO

62
Q

how many SOMITES present at DAY 24 (week 4)

A

13 SOMITE EMBRYO

63
Q

how many SOMITES present at DAY 26 (week 4)

A

27 SOMITE EMBRYO

64
Q

when does the RANIAL NEUROPORE close

A

DAY 26 (week 4)

starts closing at day 24

65
Q

when does the CAUDAL NEUROPORE close

A

DAY 28 (week 4)

66
Q

when do the DIGITAL RAYS begin to develop

A

WEEK 6 (day 42)

67
Q

when do the DIGITS SEPARATE

A

END of WEEK 8

68
Q

when is the RETINAL PIGMENT present

A

WEEK 6

69
Q

when do we have rapid development of the BRAIN and FACIAL PROMINENCES

A

WEEK 5 (day 32)

70
Q

When do the UPPER and LOWER LIMB BUDS appear

A

DAY 28 (week 4)

upper is paddle-shaped and lower is flipper-like at week 5

71
Q

when does the SCALP VASCULAR PLEXUS appear

A

WEEK 8 (day 56)

72
Q

when does the AURICULAR HILLOCKS develop (contributes to formation of external ear - auricle)

A

WEEK 6 (day 42)

73
Q

when does PRIMARY OSSIFICATION begin in FEMUR

A

WEEK 8

74
Q

when do we have VISUALLY DISTINCT HUMAN CHARACTERISTICS

A

END OF WEEK 8

75
Q

when does the embryo have a C-SHAPED CURVATURE due to folding

A

DAY 28 (week 4)

76
Q

When do we get the LENS PLACODE (primordium of lens)

A

DAY 26 (week 4)