All are true about Somites except:-
The post otic pa of paraxial mesoderm form bilateral solid cord of cells extending along the side of notochord beneath the neural tube. It undergoes segmentation to form series of paired somites. The somites are differentiated into ventro medial (sclerotome)and dorso lateral pa (dermomyotome) The somites appear between 20-30 days of development and by the end of first month, 44 pairs of somites are laid down. Thus, the 4th week of development is known as somite period. Out of 44 pairs of post otic somites: 4 are occipital, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 8-12 coccygeal.
4th week is called somite period
Dorsi-lateral pa forms the sclerotome
44 pairs are present by the end of 1st month.
Post otic pa of each paraxial mesoderm is subdivided into a number of cubical blocks known as somites.
General Embryology 2