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Aubrey- Embryology > Embryology Test 2 > Flashcards

Embryology Test 2 Flashcards

1
Q

What are the four extra embryonic layers?

A

Amnion

Yolk

Chorion

Allantois

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2
Q

What germ layer is the Chorion from?

A

Part of fetal maternal interface

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3
Q

What germ layer is the yolk from?

A

Inner cell mass; hypoblast derivative

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4
Q

Two trophoblastic derivatives of the fetal-maternal interface?

A

Placenta Chorion

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5
Q

What germ layer is the amnion from?

A

Inner cell mass: epiblast derivative

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6
Q

Four function of the amnion

A
  1. Buffer against mechanical injury
  2. Accommodate growth
  3. Allow normal movement
  4. Protects fetus from adhesions
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7
Q

What germ layer is the allantois from?

A

Inner cell mass; interfaces with placenta via umbilical cord

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8
Q

What is an excessive amount of amniotic fluid? Liquid amount? What is it associated with?

A

Hydramnios >2000 mL

Associated esophageal atresia or anencephally

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9
Q

Hydratiform mole is related to what

A

Paternal imprinting

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10
Q

What is the condition with too little amniotic fluid? Liquid amount? What is it associated with?

A

Oligohydramnios

Renal agenesis

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11
Q

What does testing A-fetoprotein tell you? What is A-fetoprotein?

A

High concentration in amniotic fluid is a strong indicator of a neural tube defect -A protein in CNS

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12
Q

Possible Yolk sac functions May concentrate (2)? Relationships (2)? Traces persist as?

A

May concentrate

  • Folic acid
  • Vitamin A, B12, E

Relationships

  • Site of origin of primordial germ cells
  • Location of blood islands

(Origin of initial blood cells)

Traces of yolk duct persists as Meckel’s diverticulum

-Outgrowth of ileum

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13
Q

Blood islands?

A

Origin of initial blood cells (extra embryonic hematopolesis)

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14
Q

Meckel’s diverticulum?

A

Traces of yolk duct persist as a fibrous cord or an out pouching of the small intestine

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15
Q

Development of allantoic vessels and relation of allantois to the urinary bladder and median umbilical ligament?

A

1)Allantoic vessels develop into mesoderm of the allantois 2)Proximal part of allantois= urachus -Associated with the formation of the urinary bladder -Becomes median umbilical lig

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16
Q

Four stages of chorionic villi development?

A

Previllous embryo Primary villous Secondary villous Tertiary villous

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17
Q

What happens in secondary villous stage?

A

Mesodermal cores appear within the primary villi

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18
Q

What tissue in the mature placenta interfaces directly with maternal uterine connective tissue?

A

Cytotrophoblast

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19
Q

What happens in the primary villous stage?

A

Solid, cytotrophoblastic ectodermal primary villi appear

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20
Q

Anchoring villi?

A

Villi that are anchored to the cytotrophoblastic shell (as opposed to floating villi)

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21
Q

What happens in the tertiary stage?

A

Characterized by the appearance of blood vessels within the mesenchymal core of the secondary villi

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22
Q

Chorionic plate (2)

A
  1. Mesoderm

Faces away from the chorionic villi and toward chorionic cavity

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23
Q

What happens in the previllous embryo?

A

No villi have been formed on the trophoblast

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24
Q

Cytrotrophoblastic shells

A
  1. Formed by expansion of the cytotrophoblastic columns over the maternal decidual cells
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25
Q

Layers of Embryo (6)

A
  1. Chorionic cavity 2. Amnion 3. Chorionic plate 4. Syncytiotrophoblast, Intervillous space, villi 5. Outer cytotrophoblastic shell 6. Decidua capsularis
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26
Q

What maternal tissue is lost at childbirth?

A

Decidua capsularis

Chorion laevae

Amnion

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27
Q

Fate of decidua capsularis?

A

Undergoes atrophy Fuses with decidua parietalis

Decidua= shed

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28
Q

Early placenta (4)

A

Thick

perm low

Small surface area

Total diffusion conductance is miniscule

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29
Q

Late placenta (4)

A

Thin

Perm high

Large surface area

Large increase in placental diffusion

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30
Q

Bohr effect

A

Hemoglobin can carry more O2 at low PCO2

  • Fetal blood carries more CO2
  • Excess CO2 diffuses into maternal [Maternal more acidic, fetal more alkaline]

Increase capacity of fetal blood to combine with O2, decrease for maternal

Shift of oxygen hemoglobin curve to right and downward forces oxygen away from hemoglobin and into tissues

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31
Q

Double Bohr effect

A

Double shift in the maternal blood and in fetal blood

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32
Q

Human chorionic gonadotropin Timing? Secretion? Targets (2) ? Effects (4) ?

A

Timing -Measureable 8-9 days -Max: 10-12th week -Lower levels: 16-20th week Secretion -Secreted by the syncytial trophoblast cells into maternal fluids Targets -Corpus luteum & testes Effects 1) Prevents involution of CL 2) Causes CL to increase secretion of progesterone and estrogen 3) Caues increased growth in CL 4) Exert interstitial cell-stimulating effect on testes of male fetus (results in production of testosterone until birth)

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33
Q

Estrogen Timing? Secretion? Targets? Effects (6)

A

Timing -Towards end of preg. secretion levels are 30x mother’s normal level Secretion - secreted by syncytotrophoblast cells of placenta -placenta estrogen formed from adrogenic steroid compounds: (formed from mother and fetal adrenal glands, converted by trophoblast cells into estradiol, estrone, estriol) Target -external genitla Effects 1) uterine enlargement 2) Breast enlargement 3) Growth of breast ductal structure 4) Enlargement of maternal ext. genitalia 5) relaxation of pelvic log 6) May affect aspects of fetal development

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34
Q

Progesterone Timing? Secretion? Target? Effect (4)

A

Timing -early by CL -Late in placenta Secretion -Secreted in small quantities by CL (early) -Secreted in large quantities by placenta (late) Targets -Decidual cells, uterus, fallopian tubes, breasts Effects 1) Causes decimal cells to develop in the endometrium 2) Decrease contractility of pregnant uterus 3) Increase secretion of fallopian tubes and uterus 4) May work with estrogen to prepare breasts for lactation

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35
Q

Human chorinic somatomammotropin Timing? Secretion? Target? Effect (3)?

A

Timing -Beginning 5th week of prey Secretion -Secreted by placenta Target -Mother Effects 1) Decrease insulin sensitivity in mother 2) Decrease utilization of glucose in mother 3) General metabolic hormone

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36
Q

Oxygen pressure gradient

  • Mother: ?
  • Fetus: ?

Reasons why adequate oxygenation can occur with such a lower pressure gradient (3)

A

Mother= 50

Fetus= 30

  1. Fetal hemoglobin has a higher affinity for oxygen
  2. Fetal blood hemoglobin concentration is aobut 50% greater than maternal
  3. Bohr effect
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37
Q

What causes limb defects, ear defects, and cardiovascular anomalies a) alcohol b) thalidomide c) retinoic acid

A

Thalidomide

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38
Q

Respriatory distress syndrome

What?

Incidence?

Fundamental deficiency in?

A

Condition related to immature lungs where lungs are under inflated, alveoli partially filled with proteinaceous fluid that forms membrane over respiratory surfaces

Incidence inversely proportional to gestational age

Funamental deficiency is in the lack of pulmonary surfactant

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39
Q

Why Hyaline membrane disease

A

Membrane composed of proteins and dead cell lines that covers the alveoli making gas exchange difficult or impossible

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40
Q

Rh disease consequences

A

Jaundice (bilirubin) Low muscle tone (hypotonia) Lethargy

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41
Q

Kernicturus

A

Brain damage from excess jaundice

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42
Q

What causes defects involving a variety of facial structures, outflow of heart and thymus

a) alcohol b) thalidomide c) retinoic acid

A

retinoic acid

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43
Q

Why no developmental insults during first 3 weeks?

A

Insults will either kill embryo or be compensated for by powerful regulatory properties

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44
Q

No major structural anomalies after week 8?

A

By this point, most organs have become well established

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45
Q

Malformation

A

are primary errors of morphogensis. Usually multifactoral

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46
Q

What causes growth and mental retardation, microcephaly, various malformation of face and trunk a) alcohol b) thalidomide c) retinoic acid

A

alcohol

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47
Q

Deformation

A

disturbances in otherwise morphogenetic processes. These are typically caused by abnormal biomechanics forces such as uterine constraints Clubfoot

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48
Q

Disruption

A

are disturbances in otherwise normal morphogenetic processes. Amniotic bands

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49
Q

Syndrome

A

are constellations of congenital anomalies that are thought to be pathologically related but cannot be explained on the basis of a single local initiation event -often caused by single event like infection

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50
Q

Critical period

A

time period during pregnancy where embryos are more susceptible to agents or factors causing abnormal development than at other times

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51
Q

Sequence

A

is a series (cascade) of events triggered by one initiating factor Oligohydraminos

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52
Q

Fetal alcohol syndrome characteristics

A

poor postnatal growth

micrcephaly

mental retardation

heart defects

long thin upper lip

epicanthic folds

palpebral fissures

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53
Q

Deficiency in folic acid in pregnagncy lead to what?

A

Neural tube defects

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54
Q

Fetal Hydrops

what?

common cause

causes x2

A

Refers to accumulation of edema fluid in teh fetus during intrauterine growth

Hemolytic anemia, incompatibliiyt between mother and fetus

Immune and nonimmune

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55
Q

Immune Hydrop

antigen?

Fetus is?

A

Blood group incompatibility

D antigen of Rh group

Rh+ fetus

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56
Q

Nonimmune Hydrops

A

cardiovacular defects such as congenital cardiac defects

anomalies turners, trisomies 21 and 18

Kernictureus

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57
Q

Melanoblasts From? Function (3)

A

From neural crest Migrate to dermis and then into epidermis Stain with HMB-45 Produce pigment by mid preg

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58
Q

Preeclampsia –> Eclampsia

Definition

Preclampsia (5)

Eclampsia (3)

A

Pregnancy induced hypertension

Preclampsia

  1. more serious condition
  2. blood pressure is higher
  3. proteinuria
  4. weight gain
  5. edema

Edema

  1. extremely serious
  2. extreme high blood pressure
  3. grand mal seizures or coma
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59
Q

Langerhans’ cells From? Function?

A

Derived from bone marrow Antigen presenting cells

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60
Q

Merkel cells From? Function?

A

Neural crest Slow adapting mechano-receptors

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61
Q

Induction of ectodermal placode (thickening)

Induction from?

A and B from what causes ectoderm to express C?

D from what causes ectoderm to express E

E and C in ectoderm block F

In interfollicular zones

What blocks wnt

What inhibits follicle development?

A

Dermal induction

Wnt-11 and FGF from mesoderm cause ectoderm to express NOggin

Eda from mesoderm causes ectoderm to express Edar

Edar adn NOggin in ectoderm block BMP

Dickkopf block Wnt

BMP inhibits follicle development

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62
Q

Wnt-1

A

Induced Wnt 11

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63
Q

Wnt 11

A

With FGF cause ectoderm to express Noggin

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64
Q

BMP

A

inhibits folicle development

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65
Q

Eda/Edar

A

Eda causes ectoderm to express Edar Edar with Noggin block BMP Edar stimulates expression of Shh

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66
Q

Noggin

A

With Edar block BMP

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67
Q

Dickkopf

A

Blocks Wnt

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68
Q

Shh

A

Formation of dermal papilla below epidermal placode -With Cyclin D1 stimulate further down growth of proliferation of epidermal placodes

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69
Q

Induction dermal papilla

Induction?

Expression of A via the signaling pathway involves B recpetor stimualtes formation of waht below what

A
  1. Epidermal induction
  2. Expression of Shh by Edar stimulates formation of dermal papilla below epidermal placode
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70
Q

Induction of hair germ (3)

Induction?

Various inducers from dermal papilla along with A and B in epidermal placode stimlate further downgrowth of proliferation of epidermal placode

Final differentiaton of hair primordial involves what?

A
  1. Dermal induction
  2. Various inducers from dermal papilla along w/ Shh and Cyclin D1 in epidermal placode stimulate further down growth of proliferation of epidermal placodes
  3. Final differentiation of hair primordial involves Hox genes
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71
Q

Estrogen

A

Stimulate growth of duct system

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72
Q

Progesterone

A

Stimulates formation of secretory alveoli

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73
Q

Prolactin

A

Stimulates synthesis of milk protein and fat

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74
Q

Oxytocin

A

Cuases milk letdown

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75
Q

Common pathway

what is induced to enter pathway?

Produces what, which promote?

A stimualtes synthesis of B and C

What is stabilized

A
  1. Mesenchyme is induced to enter common pathway 2. Production of N-cadherins which promotes mesenchymal condensation 3. TGF-beta stimulates synthesis of fibronectin and N-CAM 4. Aggregated state of mesenchymal cells is stabilized
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76
Q

Membranous bone pathway

Requires what?

What happens?

A
  1. Required transcription factors Runx-2 and Osm 2. Mesenchymal cells differentiate into osteoblasts
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77
Q

Permanent cartilage pathway

What happens?

A causes what to do waht?

A is contiually expressed

A
  1. Mesenchymal condensation forms chondroblasts 2. Sox-9 causes chondroblasts to secrete collagen II and cartilage matrix 3. Sox-9 is continually expressed in permanent cartilage
78
Q

Endocondral bone pathway

A, B, C induces this cartilage to under go what?

What secretes what and what

Invading what erode the somehting and bring in D to replace cartilage with bone

A
  1. Runx-2, ihh, and BMP-6 induce this cartilage to undergo hypertrophy 2. Hypertrophy cartilage secrete boen proteins and vascular endothelial growth factor 3. Invading blood vessels erode the hypertrophic cartilage and bring osteoblasts in to replace cartilage with bone
79
Q

Mesodermal sclerotomes (3)

A

Vertebral column

Ribs

sternum

80
Q

Vertebral column

Hox10 knock cuases what

proatalas anlage contributes to what

A

ribs formon lumbar adn sacral vertebrae

The proatlas anlage contributes to the formation of the occipital bone and the dens of atlas

81
Q

Lateral plate mesoderm

A

Limb bones

GIrdles

82
Q

Head mesoderm

A

Calvaria adn base of skull

83
Q

Neural crest

A

Facial bones

84
Q

Median Hinge point (3)

  • Induced by
  • Involved in
  • Requires
A

Induced by notochord

Involved in changes in shape of columnar cells to pyramidal shaped cells via apical constriction

Requires synthesis of actin filaments at apical ends of cells

85
Q

Lateral Hinge point

A

Also involved in apical constriction by actin filament

86
Q

Elevation of neural folds is due to?

A

Due to pushing inward by expanding non-neural epithelium

87
Q

Head organizing region

  • Consists of
  • Results from express of _____ where?
A

Consists of anterior visceral ectoderm adn prechordal plate

Results in expression of Otx-2 in forebrain/midbrain region

88
Q

Anterior notochord

Expression of and where?

A

Expression of Gbx-2 in hindbrain region

89
Q

Anterior posterior gradient

Established by?

90
Q

Isthmic organizer

Is what?

Established by what?

Organizes what?

Releases what?

Makes what?

A

Signaling center established by boundary between osx-2 and gbx-2

Important in organizing midbrain and cerebellum

Releases Wnt-1 anterior and FGF-8 Posteriorly

Induces gradients of En-1 (anterior) and En-2 (posterior)

91
Q

Anterior neural ridge signaling center

Important in?

Secretes?

A

Important in organizing telencephalon, parts of diencephalon, olfactory and pituitary gland

Secretes Shh and FGF-8

92
Q

Zona limitans signaling center

Organizes?

Secretes?

A

Organizes border between dorsal and ventral thalamus

Secretes Shh

93
Q

Krox 20 patterning in hindbrain –>

94
Q

Kreisler and Hoxa-1 in hindbrain

95
Q

Retinoic acid gradient in hindbrain

96
Q

Gbx-2 in hindbrain

97
Q

Pattern of Hox genes expression in hindbrain segmentation does what?

Stimulated by what?

Initiates expression of what?

A

Determines cranial nerve and pharyngeal arch derivatives

Stimulated by retinoic acid gradient

which initiates expression of Hoxa-1 and Hoxb-1

98
Q

Spinal cord Segmentation

What area serves as stem cell zone?

Cells in this area do what?

Presomitic mesoderm flanking posterior region secretes what?

Which does what?

Which direction does the neural tube advance?

Once fall out, what happens and is under influence of what?

Retinoic acid blocks what?

A

Caudal part of neural plate

Cells produced in this region as a result of mitotic activity continue to proliferate but do not differentiate as long as they are in this zone

Presomitic mesoderm flanking posterior regions of neural tube secrete FGF-8 which maintains these cells in a proliferative state

Advances posteriorly

Differentiate as they fall out, under influence of retionic acid

Which blocks FGF-8 and Wnt-3a

99
Q

Paraxial (segemental plate) mesoderm

What is it and where is it located?

Segmented into?

Subdivided into?

A

Thick column of mesoderm closest to and parallel with the notochord

Becomes segmented into somites

Becomes subdivided into dermatomes, myotomes, and sclerotomes

100
Q

Intermediate mesoderm

What and where?

Gives rise to?

A

Narrow column of mesoderm lateral to paraxial mesoderm

Gives rise to urogenital system

101
Q

Lateral plate mesoderm

What and where?

Splits to what?

A

Thin plate of mesoderm lateral to intermediate mesoderm

Splits to form lining of body cavities and mesoderm of most internal organs as well as limbs

102
Q

Somitomeres vs Somites

Somitomeres develop where in what?

Added to what end?

After 20 pairs, somites if first formed where?

At expense of what?

How do somites differ from somitomeres?

In what direction do somites replace somitomeres?

How many pairs constant at caudal end?

A

Somitomeres initial pair develop along neural plate in paraxial mesoderm

Added caudally

First somites addes behind 7th pair

Lose 8th pair

Somites are more dense blocks

In caudal direction somites replace somitomeres and somitomeres are replaces at caudal end

11 pairs constant

103
Q

Wave Front mechanism

Gradient of what two things?

Aka?

Results in?

What is expressed because of the specific balance?

A

FGF-8 and Retinoic acid

Determination Front

Results in cellular determination toward somitogenesis

Mesp-2

104
Q

Segmentation Clock

What molecules?

Leads to establishment of what?

Why is it called segmentation clock?

What is concentrated at anterior border of somite

What is concentrated at posterior border of anterior somite?

Cells at anterior border express?

Cells at posterior border express?

What does it result in?

A

Notch, Wnt, FGF

Leads to establishment of the pattern of somite formation

Expressed along a timeline

Lunatic fringe at anterior border

c-hairy at posterior border

Eph A (receptor) by anterior cells

Eph B (ligand) by posterior border cells

Results in a fissure between adjacent somites

105
Q

Somite Differentiation

Ectoderm dorsal to somites –> A? –> B?

B? + Decrease in C? –> mesenchymal cell to epithelial cell conversion

Formation of what?

Notochord –> D? + E? –> F? + G? in what part of somite= sclerotome

H? in what –> transformation of what half of somite into dermomyotome

Dermomyotome –> expresses I?, J?, k? –> separation of dermomyotome into ____ dermotome and ___ myotome

A

Wnt 6 –> Paraxis in somite

Paraxis + decrease in snail

Somitocoel

Shh + noggin –> Pax1 + Pax9 in ventral part of somite

Wnt genes in dorsal neural tube –> transformation of dorsal half of somite into dermomyotome

Expression of Pax3, Pax7, Paraxis–> separation into dorsal dermotome and ventral myotome

106
Q

Dermomyotome

What part of somite?

Signaling from what from where (x2) create a balance that causes the myotome portion to commit to the myogenic lineage

What inhibits BMP-4

What does BMP-4 do?

What produces BMP-4?

What does it cause to happen?

What from where signals the sclerotome to produce scleraxis, which causes what

Which is the precursor for what?

A

Dorso-lateral part of somite

Shh signaling from notochord

Wnt signaling from dorsal neural tube

Noggin inhibits BMP-4

BMP-4 inhibits myogenesis in ventrolateral dermomyotome and stimulates cells from this area to migrate from the somite into the limb bud

From Lateral plate

FGF from myotome signals sclerotome to produce scleraxis

Which cuases teh anterior and posterior borders of each somite to form the syndetome which is the precursor for tendons

107
Q

Intermediate Mesoderm

Responds to what from where? x2 to become intermediate mesoderm and epress what?

Associated with formation of what two things?

Cranial and caudal extent of IM is dependent on expression of ?

A

Respoonds to BMP (lateral ectoderm) and Activin (paraxial mesoderm)

Express Pax-2

FOrmation of pronephrox and mesonephros

Dependent of expression of Hox4-Hox11

108
Q

Early heart forming cells

Arise where?

Migrate through what?

Anterior visceral ectoderm is induced by what to form what?

Express what 3 factors

A

Epiblast

Primitive streak

BMPs and FGFs to form cardiac crescent

Nkx2-5, MEF2, GATA4

109
Q

Cells migrating through anterior primitive streak form?

A

Outflow tract

110
Q

Cells migrating through middle of primitve streak?

A

Form ventricles

111
Q

Cells entering streak most posteriorly

A

Form atria

112
Q

Cardiogenic plate

Arises from?

It will do what?

A

Arise from splanchnic mesoderm rostal to the oropharynx membrane

It will thicken to become the myocardial primordium and will form cardiac crescent

113
Q

Bilaterally paired tubes taht form cardiogenic mesoderm fuse where?

Outer layer=

Inner layer=

A

Fuse beneath foregut

Outer= myocardium

Inner= Endocardium

114
Q

Source of pericardium and myocardial fibroblast

A

Proepicardial primordium

115
Q

Neurocranium

Part of skull that?

Base if formed from what?

Origin of what?

Membranous part?

A

Part of skull that surrounds the brain

Base if formed from chondrocranium (cartilaginous)

-Origin of part of occipital, sphenoid, ethmoid, part of temporal

Membranous: part occcipital, part temporal, parietal, frontals

116
Q

Viscerocranium

Surronds what?

Cartilagionous portion:

A ( parts?)

B (parts?)

Membrnous portion

A

Surrounds oral cavity and pharynx

Cartilaginous portion forms

Pharyngeal arch I (mechel cartialge malleus, incus)

Pharyngeal arch II (reichert cartilge, stapes styloid)

Membranous: part temporal, zygomatic, maxillary, nasal, lacrimal, alatine, vomar, pterygoind paltes, mandible, typanic ring

117
Q

The mesenchyme that forms teh viscerocranium is mostly from what?

A

NEural crest

118
Q

How many pairs of pharyngeal arches?

Each pharyngeal arch consists of four components:

A

6

Skeletal element

Muscles

A branch of specific CN

Artery

119
Q

Pharyngeal arch I associate with

120
Q

PHaryngeal arch II assocaited with?

121
Q

Fontanelles and Sutures

What allows continual growth?

Separated by what?

Elongation due to A?

Intersection of more than 2 bones is?

What is expressed in all sutures?

What does it suppress, and prevent?

A

Ossification centers

Separated by synchondroses

Elongation of primary center by Shh

Intersection of more than 2 bones= fontanella

Noggin in all sutures

Suppress BMP which otherwise leads to closure of sutures

122
Q

Myogenic cells

Originate?

Restricted?

Type of cells?

A

Originate in somites

REstricte to muscle forming line

Mitotic cells

123
Q

Myoblasts

derived from?

type of cell?

A

myogenic cells

postmitotic

124
Q

Myotubes

form when?

characterized by presence of what?

FOrmation of what?

What move where

A

Formed when myoblasts line up and adhere

Characteric by actin, myosin, troponin, tropomyosin

Formation myofibrils with sacromeric arrangment

Nuclei move to periphery

125
Q

Primary myotubes

formed by?

differentiation occurs?

A

Formed by fusion of earliest myoblast

Differentiation occurs before innervation

126
Q

Secondary myoblasts

Compared to primary?

FOrmed where?

Presence of waht is necessary to form what?

Contained within?

Are what?

A

Smaller than primary

Formed along side primary from late myoblasts

Presence of motor axons may be necessary to form secondary myotues

Contained within same basal lamina

Are electronically coupled

127
Q

Satellite cells role (4)

Located

Type

Function

Note

A

Located between sacrolemma and basal lamina of myofiber

Mitotic and myogenic

Able to fuse with muscle fibers and provide for grwoth

NOte taht satellite cells do not form new msucle fibers

128
Q

Molecular regulation of muscle development

Maintain myogenic cells in labile state

A

FGF adn TGF beta

129
Q

Molecular regulation of muscle development

Does loss of mitotic capability

130
Q

Molecular regulation of muscle development

What convert non-muscle cells to cells capable to expressing muscle proteins

A

MyoD family

131
Q

Molecular regulation of muscle development

Separately can actiavte MyoD and cause mygoenic cellst o become myoblasts

A

Pax3 and Myf5

132
Q

Molecular regulation of muscle development

Increasing levels of what resutls in expression of myoblast genes by myoblast

Which express what?

A

MyoD and Myf5

Myogenin

133
Q

Results in expression of myotube gnes and myf-6

134
Q

Leads to expression of myofiber genes

135
Q

Actual morphogeneis of muscles is dependent on what?

A

Associated connective tissue framework

136
Q

Epaxial muscles arise from

A

Dorsal lip of myotome

137
Q

Expaxial tendons arise from

A

syndetome layer of somites

138
Q

Hypaxial muscles from

A

Ventral buds of myotome

139
Q

Hypaxial tendoms from

A

Lateral plate mesoderm

140
Q

Limb muscles arise from

A

Ventrolateral dermomyotome

141
Q

Muscles of head and neck from

A

Derived from paraxial somitomeres

142
Q

Extraocular muscles arise from

A

Prechordal plate

143
Q

Cranial musculature from

A

unsegmented paraxial mesoderm

144
Q

Some cranial musculature (lowe jaw) is from

A

Splanchnic mesoderm

145
Q

Cardaic muscle is derived from

Early cardiac muscualture does not express?

A

Splanchinc mesoderm

MyoD

146
Q

Remove half of limb disc

A

Remaining half will form complete limb

147
Q

Vertically dividing the limb disc into two halves adn physically separate teh two halves

A

Each half will form a complete limb

148
Q

Fuse two limb discs together

A

A single normal limb will form

149
Q

Initiation of Limb Development

Initated by

Caues to express

Each does what?

Which leads to expression of?

This causes expression of what

A

Initiated by paraxial mesoderm using retinoic acid based on HOx code

Causes limb mesoderm to epress Tbx5 or Tbx4

  • Tbx5= forelimb
  • Tbx4= hindlimb

Tbx5 0r 4 caues mesoderm to express FGF10

FGF10 causes expression FGF8

FGF8 maintains expression FGF10

150
Q

Transplant a limb disc to opposite side

A

The AP axis is reversed but not the DV axis

A normal limb will form but its AP axis is reversed

151
Q

Rotate a limb disc 180 degrees

A

Both the AP axis and the DV axis will be reversed

A normal limb will form but only its AP axis is reversed

152
Q

Transplant a strip of flank tissue from just posterior to the limb disc to an ectopic site just anterior to the limb disc

A

The resulting limb consists of two posterior halves arranged in a mirror-image fashion

Conclusion: the strip of flank tissue just posterior to the limb disc organizes the posterior edge of the disc

153
Q

Formation of Anterior-Posterior Axis

A induces expression of B

B determines position of what via highest conc

Posterior organizting region express C?

C activates D

Anterior posterior axis is fixed by expression what in where?

A

Retinoic acid induces expression Hoxb8

Hoxb8 determiens postion ZPA

Post. organize region express Retionic acid

Retinoic acid activates Shh

Anterior posterior axis is fixed by expression of Gli-3 in anterior limb and Hand-2 in posterior limb bud

154
Q

Shh?

Function

Induce

INhibits

A

Maintains structure and function AER
Induce expression gremlin

INhibits GLi-33 in poster limb bud

155
Q

Gli-3

Active wehre?

Inhibits what?

A

Active in ant. part of limb bud

Inhibits Shh in anterior limb bud

156
Q

Formation of Dorsal Ventral Axis

Dorsal limb ectoderm –> A

A does what

Ventral limb bud ectoderm –> B

B does what?

A

Dorsal limb bud ectoderm signals Wnt-7a

Wnt7a induces dorsal limb mesoderm to express Lmx-1b

Ventral limb bud ectoderm signals En1

En-1 inhibits Wnt-71

157
Q

Formation of Proximal distal axis

Apcial ectodermal ridge uses A and B to keep cells in teh underlying lim bud in proliferative state

Cells that get left behind?

Morphology of limb due to ?

A

FGFs and Wnts

Become postmitotic and differrentiate

Morphology due to Hox

158
Q

AER/ LImb mesoderm interactions

Structure of developing imb is determiend by?

Effect of limb mesoderm on overylying ectoderm?

Mesoderm produce what to maintain AER

AER maintains

What carves shape of limb/ separation digits

A

nature of mesodermal componets

instructive induction, mutant AER will not form AER

apical ectodermal maintance factor AEMF

Necrotic zones

159
Q

LImb bud mesenchyme cells from

Gives rise to?

What cuses cartialge to be restrained to central core

A

Lateral plate mesoderm

appendicualr skeletal elements

CT

BV

Wnt-7a

160
Q

Hypertrophic cells express?

A

Indian hedhog (ihh)

161
Q

Limb muscle devleopment

Migrate pre-muscles express

Before migrationg pre muscle cells in somite express which is the receptor for?

Differentiation into muscle depends on ?

What is expressed by CT and is assocated with what?

A

Pax3 adn N-cadherin

Express c-met, receptor for scatter factor

Wnt-6

Tcf-4, associated with muscle masses

162
Q

Axons originate from more medial lcoates in teh spinal cord grow into teh

A

Ventral muscle mass

163
Q

Axons originating from teh more lateral locations in spinal cord grow into

A

dorsal muscle mass

164
Q

If the forelimb rudiment of a salamander embryo is removed so that the limb fails to develop:

A

The nerve of the brachial plexus ramin smaller (thinner) than they would have been if the limb were still there

Spinal ganglia three, four, and five (associated with the brachial plexus in the salamder) are also smaller. The number of cells in each ganglion may be reduced by as much as 50%

165
Q

If an additional limb rudiment is transplanted to the flank of a salamander embryo

A

The local spinal nerves supply the innervation to the transplanted limb and these local nerves increase in thickness

Ganglia associated with the nerves increase in size; the increase in number of cells may be as much as 40%

166
Q

If the forelimb rudiment of an amphibian embryo, prior to the outgrowth of nerves, is cut out and transplanted to a position very near the original one:

A

The brachial nerves will deviate from their normal paths and will be deflected in the direction of the transplanted limb. If the distance of the transplanted limb from the original position is not too great, the brachial nerves will penetrate into the limb and ramify. The limb becomes fully functional

167
Q

If an additional limb is transplanted into the immediate vicinity of the host limb:

A

The brachial nerves will develop branches running out to the additional limb and will supply it

168
Q

If the normal path of the nerves is blocked by some obstacle:

A

The outgrowing nerves may avoid the obstacle, go around it, and still reach their normal destination

Hamburger inserted a piece of mica into a frog embryo between the spinal cord and the region where the hindlimb rudiments were to develop. The nerves formed loops around the mica plate and still reached the hindlimb rudiments

169
Q

The A and B centers are interchangeable.

You can?

Limbs transplanted to the head may be supplied by?

Can be seen to?

A

Fore and hind limb

You can transplant forelimb buds in place of hindlimb bud

fibers of the cranial nerves, and then they can be seen to move synchronously with the respiratory movements of the jaws and gills

170
Q

If the limb rudiment transplant is placed further away from the normal limb site, or if the obstacle between the spinal cord and limb rudiment is too great:

A

The nerve fibers fail to be attracted to the limb

If the limb rudiment is placed on the flank of the embryo, it will attract the local spinal nerves. These nerves will grow into the limb, but they cannot provide for the normal limb function

It appears that only the areas of the spinal cord from which the nerves of the brachial and lumbar plexuses originate possess the properties necessary for controlling the functioning of the limbs

171
Q

An eye was transplanted into the side of an embryo after the forelimb rudiemnt was removed

A

The brachial nerves were deflected form their normal path and grew out toward the transplanted eye

Having approached the eye, however, the brachial nerves fial to penetrate into the eye and establish an actual connection with it

It would seem then that the attraction of the outgrowing nerves to peripheral organs seems to be unspecific to a very high degree; possibly any growing mass of tissue will attract a nerve that is sufficiently near to it Connections between a nerve and the end organ can be made only if the two correspond to each other

172
Q

If metaphase plate is perpendicualr to inner margin of neural tube (next to lumen)?

A

Two daughter cells will remain proliferative

173
Q

If metaphase palte is parallel to inner margin

A

Daughter cells closest to lumen will remain proliferative

Daughter cell further from lumen will:

express notch receptor

become post mitotic

MOve to external limiting membrane

become neuroblast (pre-neuron)

174
Q

Ventral signaling

Induces formation floor plate via A

A produced by floor plae induces formation of what

A

Notochord induces formation floor palte of neural tube

Via sonic hedgehog

Shh produces formation of motor neurons

175
Q

Dorsal SIgnaling

What uses A to induce B in teh future neural crest and later to maintain C and D to create what effect?

Expression of C and D is suppressd by E from floor plate to suppress dorsaling effect in teh basal plate

A

Ectoderm flanking neural plate uses BMPs to induce

Snail2 in future neural crest

Later maintain Pax 3 and Pax7 to create a dorsalizign effect

Expression of Pax3 and Pax7 is suppressed by Shh from floor plate to suppress dorsalizing effect in basal plate

176
Q

Regional Differentation of Neural Tube

What is located between midbrain and hindbrain

Does what?

Acts by production of A (anteriorly) and B (posteriorly)

It is a what?

Principle signaling molecule is C?

D/E induce expression of:

A

Isthmic organizer

signaling center

Organizes and polarizes dorsal midbrain and cerebellum

Acts by production of Wnt-1 adn FGF-8

Principle signaling moleucles is FGF-8

FGF-8/Wnt-1 induces expression of:

En1, En2, Pax2 adn Pax5

177
Q

Dorsoventral patterning of midbrain

Primarily due to A located where?

A restricts expression of B

B is realted to formation of what

C is expressed of what of what

C function

A

Primarily due to Shh located ventrally

Shh restricts expression of Pax7

Pax7 is related to formation of alar plate

Pax6 is expressed in alar palte of diencephalon and is “master gene” of eye formation

178
Q

Cranial Nerve V (arch I)

what rhombomere?

axons of what join what?

A

Rhombomere 2

Axons of rhombomere 3 join rhombmere 2

179
Q

Cranial N VII

rhombomere?

what arch?

what rhomomere joins?

A

Rhomomere 4

Arch II

Rhombomere 5 joins

180
Q

Cranial nerve IX

Rhomomere?

arch?

what rhomomere joins?

A

Rhomomere 6

Arch 3

Rhombomere 7 joins

181
Q

Influence of local environment (4)

A

Chemoattraction

Contract attraction

Chemorepulsion

Contact repulsion

182
Q

Microenvironment cues: (4)

A

Cuadal half of somite

Fibronectin and laminin

Integrins

Cadherins

183
Q

What is teh master gene of eye formation

184
Q

Sympathetic preganglionic motor neurons?

A

Arise from intermediate (lateral) horns of gray matter

Neural tube

185
Q

Parasympathetic preganglionic motor neurons?

A

Arise from intermediate (lateral) horns of gray matter or from nuclei of hind brain

Neural tube

186
Q

Preganglionic axons synapse with?

A

cell bodies of postsynaptic sympthateic motor enurons wiithin ganglin

neural tube

187
Q

All autonomic ganglia are derived from

A

neural crest cells

188
Q

All postgagnlionic autonomic neurons are derived from

A

neural crest cells

189
Q

What is responsibel for the conversion of postganglionic sympathetic neurons from the typical form to the used inthe innervation of sweat glands

A

Cholinergic differential factor

Aubrey- Embryology (7 decks)

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