Chapter 14- Mesoderm-paraxial and intermediate

1. Fig. 14.1- mesoderm lineages 3. ________ 1. ______ 2. __________ Circulatory, Body cavity, extraembryonic Head Somites Kidney, gonads Cartilage, skeletal, dermis 24hr Fig. 14.2- mesoderm lineages in chick 48hr Chapter 14- Mesoderm-paraxial and intermediate Recall lineages: Notochord Fig. 12.4

2. Neural tube Head Somites Cartilage, skeletal, dermis Chapter 14- Mesoderm-paraxial and intermediate Fig. 14.3 1. Paraxial mesoderm 1. Paraxial a. 4 components of somite formation • __________________- • somites form from ____________ in regular intervals • total number of somites is __ in chicks, __ in mice • 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

3. 1. Paraxial mesoderm 4 components of somite formation (cont.) 3. ___________________________ • Distinct somites give rise to distinct __________ • Specific ___ gene expression predicts the type of vertebra formed Somites hox5 hox6 hox9 hox10 Fig. 11.40-Mouse somites mapped to vertebrate regions and to specific_____ gene expression

4. 1. Paraxial mesoderm (cont.) Sclerotome cells Fig. 14.7 4 components of somite formation (cont.) • 4. _____________________- somites form • cartilage of ____________ and ribs • ___________ of rib cage, limbs and back • dermis of the dorsal _________ Some somite cells become mesenchymal cells again to form ___________________- these will become _____________ of vertebrae and ribs

5. 1. Paraxial mesoderm (cont.) 4 components of somite formation 4. Differentiation-(continued) Somites have three ________________ regions that follow distinct fates: b. ______ muscles a. _______ A Fig. 14.9 c. Body wall __________ B Sclerotome What proteins are involved?? A ___________ produces NT-3 and ____ proteins that influence somite cell fate ____________ produces ___________________ to influence sclerotome fate B

6. Myogenesis What dictates the muscle phenotype? ______ is a transcription factor that activates transcription factors Myf5 and MyoD Wnt? Pax3 Myf5 + MyoD Muscle-specific genes MyoD binding site 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

7. Osteogenesis (Bone development) What dictates the bone development? • There are three lineages that produce bone- • ________ (vertebrae/ribs) • ________________ (limbs)- Not yet discussed • Cranial _____________ (head/face) • Osteogenesis occurs by two mechanisms • _______________ossification- bone without cartilage precursor • _________________ ossification- cartilage converted to bone 1. Intramembrane ossification Mesenchyme ___________cells Cell _____________ Differentiate into _________ (secrete collogen-proteoglycan matrix) Differentiate into __________ (bone cell)

8. 1. Intramembrane ossification (cont.) Mechanism of ___________________ossification) Transcription factor ________ plays a key role BMP proteins also are important _______ Mesenchyme Differentiate into osteoblast Activates expression of several _________________ genes WT CFB1A -/- ________ KO- all ossification prevented Blue- cartilage Red- Bone Fig. 14.12 Human disease- _____________________ (CCD)- due to mutations in the ______ gene

9. 2. Endochondral ossification A B C Pax Mesenchyme _______ Differentiate into__________ E D Proliferation ceases, ______ is modified __________ invade, Chondocytes die Proliferate and form _____ of bone by producing an EM F Adjacent cells (not chondrocytes) differentiate into __________ to fill in bone A B C D E Fig. 14.13 F

10. ______________ - 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

11. Intermediate Mesoderm Fig. 14.1- mesoderm lineages Recall lineages Lateral Intermediate Paraxial Circulatory, Body cavity, extraembryonic Kidney, gonads Head Somite Fig. 12.4 Cartilage, skeletal, dermis Kidney development Three stages

12. Kidney development Three stages 1. ________________ arises from intermediate mesoderm just ventral to anterior somites and migrates toward tail Pronephros Nephric Duct 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 Fig. 14.18

13. Kidney development Three stages Pronephros Stage 3. (cont.) Nephric Duct • The ________________produces: • ______________ stem cells • __________ carrying tubes (In some mammals) The ______________tubules are formed from mesenchyme, which induces ____________ buds (these become ureters that transport urine from _______________) Fig. 14.18

14. Ureteric bud and metanephrogenic mesenchyme interact to become the kidney- called _______________________ 1. __________________ mesenchyme (MM) formed 2. MM secretes GDNF and ____ to induce ___________________ formation 5. MM induces __________ of ureteric bud 4. Ureteric bud secretes _____ to induce mesenchyme cells to aggregate and become ___________ Mechanism of ______________________ Fig. 14.19 3. Ureteric bud secretes ____ and _____ to prevent _________ of MM 6. _______________ and growth of the ureteric bud.