Dorsolateral dermatome and medial ventral
myotome. Dermatome cells migrate o ectoderm at segmental level, collaborate
with LPM to form dermis. Myotome to epimere and hypomere. Epi, deep muscles of
back including the erector spninae and transverso spinalis groups. Thoracic
hypomere 3 layers of anterior lateral muscle of latral and ventral body wall
in thorax and abdomen. Intercostals in the thorac and external oblique,
internal oblique and transversus abdominus and rectus adomis mucles that flank
midline. Rectus coloum is usually confined to abdomen but may sneak up to
thorax as sternalis muscle. Page 85 in text. Tendons and internal connective
tissue of muscle from somatopleure.
Cranial expression of hox genes in mice
parallel their sequence on the chromosomes and sensitivity to retinoic acid.
Combinatorial code – specify a somite or small group of somites but where from
between somites or recombined caudal and cranial halves is not known.
REMEMBER TO POINT OUT PROGRESS ZONE
MESENCHYME HAS MEMORY OF HOW LONG IT
SPENT IN THE PROGRESS ZONE
Mirror image suggests diffusible
substance, morphogen, that establishes a concentration gradient.