Mesoderm segmentation

What does this image display?

primitive pit, groove and ridge of the chick embryo, critical for AP axis establishment in the chick

Where does the mesoderm form and at what developmental stage?

at the primitive streak during gastrulation

Describe the process by which cells obtain a specific fate at the primitive streak

cells re-emerge below the epiblast and migrate, depending on where they re-emerge determines their fate, mesoderm cells migrate laterally

What are 4 different origins of mesodermal tissues?

axial, paraxial, intermediate and lateral

What originates from intermediate mesoderm?

kidney and gonads

What originates from axial mesoderm?

notochord and pre-chordal mesoderm

What originates from paraxial mesoderm?

head and somites → sclerotome (cartilage), syndotome (tendons), myotome (skeletal muscle), dermatome (dermis, skeletal muscle), endothelial cells

What originates from lateral plate mesoderm?

splanchnic (circulatory system), somatic (body cavity, pelvis, limb bones), extra-embryonic

What is another name for paraxial mesoderm, informing on its specification?

somitic mesoderm

What are somites?

segmented stereotypical paraxial mesoderm tissues, earliest evidence of segmentation in vertebrates

What does this show about mesoderm segmentation throughout evolution?

highly conserved across vertebrates and invertebrates - dark strip shows engrailed 1 expression which shows conserved expression and formation of somites

What does somite number dictate? How does it differ between humans and chick/mouse/zebrafish?

Describe the formation of somites

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