Dynamic changes in Hox Gene Expression during Somite and Neural Tube Development

Abstract

"Mammalian embryonic development is when body pattern is established and all organs are formed. Hoxa5 is expressed in lung, neural tube, somites, diaphragm, foregut, midgut, and patterns the cervical-thoracic region of the axial skeleton while Hoxa11 is expressed in the neural tube, somites, and zeugopod during early development of the embryo. The dynamic changes in Hoxa5 and Hoxa11 expression during somite differentiation and neural tube patterning has yet to be determined. This study investigated Hoxa5 and Hoxa11 expression in mice at various time points between E9.5-E12.5 using whole-mount visualization and cryosectioning. Hoxa5 was observed throughout the sclerotome and hypaxial lip of dermomyotome contributing to proper vertebral formation, rib placement and fibroblast populations. Hoxa5 was also shown in precursor cells of the central nervous system and motor neurons which later become useful for innervating the diaphragm. Hoxa11 was observed in the somites present at the posterior end of hindlimb bud and into the tail as well as sclerotome progenitors for the proper formation of the sacral and caudal vertebrae and myotome progenitors necessary to pattern the zeugopod. Hoxa11 was also shown in precursor cells of the central and peripheral nervous system and motor neurons."