Figure 9
From: Mechanism of primitive duct formation in the pancreas and submandibular glands: a role for SDF-1
Development and banching morphogenesis of the pancreas. Pancreatic specification of polarized endodermal cells leads to the formation of a multilayered and then globular mass of epithelial cells with a central duct lumen (pancreatic bud). This lumen, connected to the gut tube lumen, forms extensions within the pancreatic bud, and is surrounded by several layers of cells, linked by adherens junctions (E-cadherin), but lacking tight junctions (ZO-1). Around e11.5, before remodeling of the mass, some cells at the periphery acquire apico-basal polarity and delineate blind lumina (secondary lumina). Initial branching morphogenesis events result from the coalescence of secondary and central lumina, allowing the progression towards epithelial monolayers.