Endocrine G cells, primarily located in the gastric antrum, secrete gastrin. Gastrin induces acid secretion and gastric motility, and stimulates mucosal proliferation.
During embryonic development of the pancreas, gastrin-producing G-cells are transiently relatively abundant. At E14.5, approximately 0.6% of the cells expressed gastrin (compared to 0.7% of the cells that expressed insulin). Gastrin expression declines gradually to below detection threshold by post-natal day 7.
As in alpha cells, the development of these cells requires expression of Nkx2.2 and Arx in addition to Ngn3. However, gastrin-producing cells are unique in that their development does not depend on Pax6 or Pax4.
Controversy remains with regards to the exact developmental process of these cells, as it has been postulated that gastrin+ cells may originate
from alpha, epsilon or PP cells. Since G-cells can arise in the absence of these cells types, it seems unlikely, but requires further lineage-tracing experimentation.
Pathological pancreatic gastrin expression can be observed in gastrin-secreting neuroendocrine tumors (gastrinomas).