Myotome

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Myotome
Scheme showing the manner in which each vertebral centrum is developed from portions of two adjacent segments. (Myotome labeled in upper right.)
Transverse section of a human embryo of the third week to show the differentiation of the primitive segment. ao. Aorta. m.p. Muscle-plate. n.c. Neural canal. sc. Sclerotome. s.p. cutis-plate. ("Muscle-plate" is an older term for "myotome.")
Gray's subject #17 80
Carnegie stage 13/14
Precursor somite
Gives rise to muscle

In vertebrate embryonic development, a myotome is a group of tissues formed from somites that develop into the body wall muscle.

Each myotome divides into a dorsal epaxial part and a ventral hypaxial part.

The epaxial muscle mass loses its segmental character to form the extensor muscles of the neck and trunk.

The myoblasts from the hypaxial division form the muscles of the thoracic and anterior abdominal walls.

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Mammalian development of embryo and development and fetus (some dates are approximate - see Carnegie stages) - edit - discuss

Week 1: Zygote | Morula | Blastula/Blastomere/Blastosphere | Archenteron/Primitive streak | Blastopore | Allantois | Trophoblast (Cytotrophoblast | Syncytiotrophoblast | Gestational sac)

Week 2: Yolk sac | Vitelline duct | Bilaminar disc

Week 3: Hensen's node | Gastrula/Gastrulation | Trilaminar embryo Branchial arch (1st) | Branchial pouch | Meckel's cartilage | Somite/Somitomere | Germ layer (Ectoderm, Endoderm, Mesoderm, Chordamesoderm, Paraxial mesoderm, Intermediate mesoderm, Lateral plate mesoderm)

Histogenesis and Organogenesis

Circulatory system: Primitive atrium | Primitive ventricle | Bulbus cordis | Truncus arteriosus | Ostium primum | Foramen ovale | Ductus venosus | Ductus arteriosus | Aortic arches | Septum primum | Septum secundum | Cardinal veins

Nervous system: Neural development/Neurulation | Neurula | Neural folds | Neural groove | Neural tube | Neural crest | Neuromere (Rhombomere) | Notochord | Optic vesicles | Optic stalk | Optic cup

Digestive system: Foregut | Midgut | Hindgut | Proctodeum | Rathke's pouch | Septum transversum

Urinary/Reproductive system: Urogenital folds | Urethral groove | Urogenital sinus | Kidney development (Pronephros | Mesonephros | Ureteric bud | Metanephric blastema) | Fetal genital development (Wolffian duct | Müllerian duct | Gubernaculum | Labioscrotal folds)

Glands: Thyroglossal duct

Uterine support: Placenta | Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) | Amniotic sac (Amnion, Chorion)

Limb development: Limb bud | Apical Ectodermal Ridge/AER