Development of the digestive system Development of the digestive system The development of the digestive system concerns the epithelium of the digestive system and the parenchyma of its derivatives, which originate from the endoderm. Connective tissue, muscular components, and peritoneal components originate in the mesoderm. Different regions of the gut tube such as the esophagus, stomach, duodenum, etc. are specified by a retinoic acid gradient that causes transcription factors unique to each region to be expressed. Differentiation of the gut and its derivatives depends upon reciprocal interactions between the gut endoderm and its surrounding mesoderm. Hox genes in the mesoderm are induced by a Hedgehog
The Hardest Part Is the Night The Hardest Part Is the Night "The Hardest Part Is the Night" is a single by American rock band Bon Jovi. It is taken from their second album, "7800° Fahrenheit". It is notable for being the first Bon Jovi single to be released in the UK, where it charted at #68. It was the only single from the album not to chart in the U.S. Among Bon Jovi's early songs, "The Hardest Part is the Night" is the one that expresses most clearly Jon Bon Jovi's concerns with working class issues and the struggles of the underdog, a theme that