Fig. 1.

a A hypothetical model for differentiation of the SGC and GC lineage, respectively, in the HPT of freshwater crayfish. Type I cells represent a pluripotent stem cell, Type II cells are SGC and GC precursors while Type III and Type IV represent GC precursors, and finally Type V is a precursor of SGC. The specific marker proteins are indicated at the side of the different cell types. b The location of the HPT in freshwater crayfish is indicated by an arrow and is located at the dorsal part of the stomach underneath the carapace. c Isolated HPT cells cultured for 3 days in culture medium containing Ast1. This figure was originally published in Lin and Söderhäll (2011). © by the American Society of Hematology