What is embryological origin of digestive tract, tooth and pancreas?

1.	What is embryological origin of digestive tract, tooth and pancreas?
Answer» The gastrointestinal tract (GIT) arises initially during the process of gastrulation from the endoderm of the trilaminar embryo (week 3) and extends from the buccopharyngeal membrane to the cloacal membrane. The tract and associated organs later have contributions from all the germ cell layers.While crown formation is accomplished during\xa0embryonic\xa0development,\xa0tooth\xa0root formation occurs in mice molar\xa0teeth\xa0at postnatal stages and lasts for up to three weeks. During root formation, cemento blasts are formed from the mesenchymal\xa0tooth\xa0compartment and secrete cementum, which surrounds the forming\xa0tooth\xa0root.As part of\xa0embryonic\xa0development, the\xa0pancreas forms as two buds from the fore gut, an\xa0embryonic tube that is a precursor to the gastrointestinal tract. It is therefore of endodermal\xa0origin.\xa0Pancreatic development begins with the formation of a dorsal and ventral\xa0pancreatic\xa0bud.

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