module 10: tetrapod limb development

0.0(0)
Studied by 0 people
call kaiCall Kai
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
GameKnowt Play
Card Sorting

1/15

encourage image

There's no tags or description

Looks like no tags are added yet.

Last updated 4:01 PM on 4/30/26
Name
Mastery
Learn
Test
Matching
Spaced
Call with Kai

No analytics yet

Send a link to your students to track their progress

16 Terms

1
New cards

stylopodium

1st single element in limb, more proximal

2
New cards

zeugopodium

2 elements/bones, middle of axis

3
New cards

autopodium

more diversified

support weight

carpals, digits

more distal

4
New cards

homologous elements in tetropod limbs

  • hox clusters determine domains of expression

  • stylopodium, zeugopodium, autopodium

<ul><li><p>hox clusters determine domains of expression</p></li><li><p>stylopodium, zeugopodium, autopodium</p></li></ul><p></p>
5
New cards

distal dominance

hox genes expressed more distally override more proximal hox expression

<p>hox genes expressed more distally override more proximal hox expression</p>
6
New cards

limb fields

  • center = free limb/limb proper

  • shoulder girdle

  • peribrachial flank tissue

  • ring of cells with limb potentiality

<ul><li><p>center = free limb/limb proper</p></li><li><p>shoulder girdle</p></li><li><p>peribrachial flank tissue</p></li><li><p>ring of cells with limb potentiality </p></li></ul><p></p>
7
New cards

what components does the limb come from?

  1. cells coming from paraxial mesoderm —> limb muscle

  2. cells from lateral plate mesoderm→ limb bones

8
New cards

progress zone Pz

  • mesenchymal cells

9
New cards

apical ectodermal ridge

  • expresses fgf8 (mutfgf8 = stops limb growth)

  • part of ectoderm

<ul><li><p>expresses fgf8 (mutfgf8 = stops limb growth)</p></li><li><p>part of ectoderm</p></li></ul><p></p>
10
New cards

zone of polarizing activity ZPA

  • expresses ssh

    • thumb to pinky gradient

    • mutation — polydactyly, mirrored fingers

<ul><li><p>expresses ssh</p><ul><li><p>thumb to pinky gradient</p></li><li><p>mutation — polydactyly, mirrored fingers </p></li></ul></li></ul><p></p>
11
New cards

events of limb development

  1. induction of limb bud: high RA, no fgf8

  2. outgrowth: fgf8 expression distally

  3. cell specification: as fgf8 increases, RA decreases

<ol><li><p>induction of limb bud: high RA, no fgf8</p></li><li><p>outgrowth: fgf8 expression distally</p></li><li><p>cell specification: as fgf8 increases, RA decreases</p></li></ol><p></p>
12
New cards

limb bud induction: FORELIMB

  • forelimb develops in RA permissive field

  • (mesoderm) high RA → +TBX5 (TF) → + wnt2b → (ectoderm) +fgf10 → +Wnt3a → + fgf8

    • + feedback loop: fgf8 → + fgf10 → + TBX5

  • TBX5 = forelimb identity

  • fgf10 = cell division

<ul><li><p>forelimb develops in RA permissive field</p></li><li><p>(mesoderm) high <strong>RA </strong>→ +<strong>TBX5 </strong>(TF) → + wnt2b → (ectoderm) +<strong>fgf10 </strong>→ +Wnt3a → + fgf8</p><ul><li><p>+ feedback loop: fgf8 → + fgf10 → + TBX5</p></li></ul></li><li><p>TBX5 = forelimb identity </p></li><li><p>fgf10 = cell division</p></li></ul><p></p>
13
New cards

limb bud induction: HINDLIMB

  • starts with signal NOT RA

  • (mesoderm)? -→ + pitx1 OR Islet1 -→ + TBX4 →+ wnt2b → +(ectoderm) fgf10 → +wnt3a → + fgf8

    • + feedback loop: fgf8 → + fgf10 → + TBX5

  • TBX4 = hindlimb identity

<ul><li><p>starts with signal NOT RA</p></li><li><p>(mesoderm)? -→ + pitx1 OR Islet1 -→ + <strong>TBX4 </strong>→+ wnt2b → +(ectoderm) <strong>fgf10 </strong>→ +wnt3a → + fgf8</p><ul><li><p>+ feedback loop: fgf8 → + fgf10 → + TBX5</p></li></ul></li><li><p>TBX4 = hindlimb identity</p></li></ul><p></p>
14
New cards

2 paths to Fgf10 expression

  1. TBX5 → wnt2b → Fgf10

  2. fgf8 → fgf10 → TBX5/TBX4

    1. fgf8 = sufficient to induce ectopic chimera limb

15
New cards

apical ectodermal region mutations

knowt flashcard image
16
New cards

heterochronic transplantation

  • transplant young Pz into old limb bud embryo = duplicated elements

  • time is important → determines signaling environment