An immunohistochemical study of the insulin-, glucagon- and somatostatin-immunoreactive cells in the developing pancreas of the chicken embryo

The distributions and relative frequencies of insulin-, glucagon- and somat ostatin-immunoreactive cells were studied in dorsal, ventral, third and spl enic lobes of developing chicken pancreas during embryonic periods (10 days of incubation to hatching) by immunohistochemical methods. The regions of pancreas were subdivided into three regions: exocrine, light and dark islet . Round, oval and spherical shaped immunoreactive cells were detected in al l four lobes. According to developmental stages, the types of lobes and the regions of pancreas showed various distributions and relative frequencies. In the splenic robes, insulin, glucagon and somatostatin-immunoreactive ce lls were detected in exocrine, dark islet and light islet from time differe ntiation of splenic lobes, 13 days of incubation. The insulin- and somatost atin-immunoreactive cells of the third lobes were detected in exocrine and light islets from 10 days of incubation, and in dark islets from 15 and 11 days of incubation respectively. Glucagon-immunoreactive cells were detecte d in exocrine, dark and light islets from 16, 11 and 19 days of incubation respectively. These immunoreactive cells of the ventral lobes were detected in exocrine and light islets, However, dark islets were not found in this lobe. Insulin-immunoreactive cells were demonstrated from 10 days of incuba tion in these two regions. Glucagon-immunoreactive cells were detected from 17 days of incubation in exocrine and 16 days of incubation in the light i slets. Somatostatin-immunoreactive cells were demonstrated from 11 days of incubation in exocrine and 14 days of incubation in the light islets. In th e dorsal lobes, insulin-immunoreactive cells were demonstrated in exocrine, dark and light islets from 12, 14, and 13 days of incubation, respectively . Glucagon- and somatostatin-immunoreactive cells were detected in dark and light islets from 13 and 14 days of incubation, respectively. Glucagon- an d somatostatin-immunoreactive cells were demonstrated from 10 and 11 days o f incubation in exocrine respectively, Generally, insulin-immunoreactive ce lls were increased in light islets but decreased in light islets with devel opmental stages. However, glucagon-immunoreactive cells were decreased in l ight islets but increased in dark islets. In addition, somatostatin-immunor eactive cells showed the same frequencies in light and dark islets with dev elopmental stages except exocrine which increased with developmental stages . (C) 2000 Harcourt Publishers Ltd.