Chapter 14- Mesoderm-paraxial and intermediate

Recall lineages:

Fig. 12.4

Fig. 14.1- mesoderm lineages

Fig. 14.2- mesoderm lineages in chick

24hr

48hr

Kidney, gonads

2. __________

Cartilage,skeletal, dermis

Head Somites

1. ______

Circulatory,Body cavity,

extraembryonic

3. ________Notochord

Chapter 14- Mesoderm-paraxial and intermediate

a. 4 components of somite formation

1. __________________-

• total number of somites is __ in chicks, __ in mice

• somites form from ____________ in regular intervals

1. Paraxial mesoderm Fig. 14.3Neural tube

Mechanism? Involves the _______ gene_____ gene expression correlates with positioning of somites

•This effect is _____________ of all surrounding tissue

2. __________________- mesenchyme is converted to epithelium prior to final somite formation

• EM proteins fibronectin and N-cadherin link cells into clustered units

Cartilage,skeletal, dermis

Head Somites

1. Paraxial

4 components of somite formation (cont.)

3. ___________________________

•Distinct somites give rise to distinct __________

1. Paraxial mesoderm

Fig. 11.40-Mouse somites mapped to vertebrate regions and to specific_____ gene expression

•Specific ___ gene expression predicts the type of vertebra formed

hox5

Somites

hox6 hox9 hox10

Paraxial

Head Somite

Cartilage,skeletal, dermis

4 components of somite formation (cont.)

1. Paraxial mesoderm (cont.)

Some somite cells become mesenchymal cells again to form ___________________- these will become _____________ of vertebrae and ribs

Fig. 14.7

Sclerotome cells

Paraxial

Head Somite

Cartilage,skeletal, dermis

4. _____________________- somites form 1) cartilage of ____________ and ribs2) ___________ of rib cage, limbs and back 3) dermis of the dorsal _________

4 components of somite formation

1. Paraxial mesoderm (cont.)

4. Differentiation- (continued)

Fig. 14.9

Somites have three ________________ regions that follow distinct fates:

a. _______

c. Body wall __________

b. ______ muscles

Sclerotome

___________ produces NT-3 and ____ proteins that influence somite cell fate

____________ produces ___________________ to influence sclerotome fate

A

A

B

B

Paraxial

Head Somite

Cartilage,skeletal, dermis

What proteins are involved??

Myogenesis

What dictates the muscle phenotype?______ is a transcription factor that activates transcription factors Myf5 and MyoD

Pax3Wnt? + MyoDMyf5

MyoD binding site Muscle-specific genes

Signaling pathway to activate muscle-specific genes (Figure not in text)

Introduction of ______ into other cell types converts them to ______

Myoblasts fuse to form ___________ to produce muscle ______

Fig. 14.10

Osteogenesis (Bone development)What dictates the bone development?

There are three lineages that produce bone-1) ________ (vertebrae/ribs)2) ________________ (limbs)- Not yet discussed3) Cranial _____________ (head/face)

Osteogenesis occurs by two mechanisms1) _______________ossification- bone without cartilage precursor2) _________________ ossification- cartilage converted to bone

___________cells Mesenchyme Cell _____________

Differentiate into _________ (secrete collogen-

proteoglycan matrix)

Differentiate into __________ (bone cell)

1. Intramembrane ossification

Mechanism of ___________________ ossification)

Transcription factor ________ plays a key role

BMP proteins also are important

Mesenchyme Differentiate into osteoblast_______

Activates expression of several _________________ genes

________ KO- all ossification prevented

Fig. 14.12

Blue- cartilageRed- Bone

WT CFB1A -/-

Human disease- _____________________ (CCD)- due to mutations in the ______ gene

1. Intramembrane ossification (cont.)

Mesenchyme _______

Proliferate and form _____ of bone by producing an EM

Pax

2. Endochondral ossification

Differentiate into__________

__________ invade,

Chondocytes die

Proliferation ceases, ______

is modified

Adjacent cells (not

chondrocytes) differentiate

into __________ to fill in bone

A

A B

B

E D

C

C D E

Fig. 14.13

F

F

______________ - cells which hollow out bones to form cavities

• Osteoclasts enter through _____________• Osteoclasts are likely form blood-lineage ____________

The disease ___________ occurs if too ______ osteoclast activity- bones become brittle

The disease ___________ occurs if too ___________ osteoclast activity- bones are not hollowed out enough

Intermediate Mesoderm

Recall lineages

Fig. 12.4

Fig. 14.1- mesoderm lineages

Intermediate Paraxial Lateral

HeadKidney, gonads

Somite

Cartilage,skeletal, dermis

Circulatory,Body cavity,

extraembryonic

Kidney development

Three stages

Kidney development

Three stages

1. ________________ arises from intermediate mesoderm just ventral to anterior somites and migrates toward tail

2. _________________ cells induce mesenchyme to form ______________(tubules)

3. Pronephric tubules degenerate, but a new set of _____________ tubules are formed (approx 30 in humans) further down

Pronephros

Nephric Duct

Fig. 14.18

Kidney development

Three stages

The ________________produces:a. ______________ stem cells b. __________ carrying tubes (In

some mammals)

Pronephros

The ______________tubules are formed from mesenchyme, which induces ____________ buds (these become ureters that transport urine from _______________)

Nephric Duct

Fig. 14.18

Stage 3. (cont.)

Fig. 14.19

Ureteric bud and metanephrogenic mesenchyme interact to become the kidney- called _______________________

Mechanism of ______________________

1. __________________ mesenchyme (MM)

formed

3. Ureteric bud secretes ____ and _____ to prevent _________ of MM

2. MM secretes GDNF and ____ to induce ___________________ formation

4. Ureteric bud secretes _____ to induce mesenchyme cells to aggregate and become ___________

5. MM induces __________ of ureteric bud

6. _______________ and growth of the ureteric bud.