Hematopoiesis II

Question 1

Red Marrow

Answer 1

Found in Flat bones (skull, sternum, ribs, vertebrae and plevis) Long Bones (spongy/ cancellous, trabecular bone at epiphysis)

Question 2

Yellow Marrow

Answer 2

Found in shaft of long bones just fat

Question 3

Reticular Cells

Answer 3

Reticular Cells produce reticulin fibers that exten into the hematopoietic compartments and form a meshwork on which hematopoietic cells rest

Question 4

T or F? Adipocytes are stromal cells

Answer 4

True

Question 5

Osteoblast-Hematopoietic Stem Cell Interaction

Answer 5

CXCR4 is expressed on HSC SDF-1 is expressed by osteoblasts in stromal niche Mobilization: GCSF causes releases of cathepsn G and elasate, MMP9 from neutrophils These enzymes cleave and inactive SDF-1 causing HSC to leave Honing: CXCR4 are chemoattracted to SDF-1 expressed by Osteoblasts and migrate from blood vessel.

Question 6

Stromal Cells

Answer 6

Fibroblasts - secrete extracellular matrix Endothelial Cells - secrete cytokines IL5 and adhesision molecule E-selectin Macrophages- recycle and regulation of hematopoiesis Osteoblasts - regulation of micro envt via SDF-1 Adipocytes - express leption, osteocalcin receptros and influence osteogenesis