1. 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

2. 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. 14.3 Neural 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 HeadSomites 1. Paraxial

3. 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 hox6hox9hox10

4. 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 4. _____________________- somites form 1)cartilage of ____________ and ribs 2)___________ of rib cage, limbs and back 3)dermis of the dorsal _________

5. 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 What proteins are involved??

6. 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

7. Osteogenesis (Bone development) What dictates the bone development? There are three lineages that produce bone- 1)________ (vertebrae/ribs) 2)________________ (limbs)- Not yet discussed 3)Cranial _____________ (head/face) Osteogenesis occurs by two mechanisms 1)_______________ossification- bone without cartilage precursor 2)_________________ ossification- cartilage converted to bone ___________cells Mesenchyme Cell _____________ Differentiate into _________ (secrete collogen- proteoglycan matrix) Differentiate into __________ (bone cell) 1. Intramembrane ossification

8. Mechanism of ___________________ ossification) Transcription factor ________ plays a key role BMP proteins also are important MesenchymeDifferentiate into osteoblast _______ Activates expression of several _________________ genes ________ KO- all ossification prevented Fig. 14.12 Blue- cartilage Red- Bone WTCFB1A -/- Human disease- _____________________ (CCD)- due to mutations in the ______ gene 1. Intramembrane ossification (cont.)

9. 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 CDE Fig. 14.13 F 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 Recall lineages Fig. 12.4 Fig. 14.1- mesoderm lineages IntermediateParaxial Lateral Head Kidney, gonads Somite Cartilage, skeletal, dermis Circulatory, Body cavity, extraembryonic Kidney development Three stages

12. 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

13. 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.)

14. 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.