IMMUNOCYTOCHEMICAL STUDY ON THE PP CELL OF RAT PANCREATIC ISLETS DURING POSTNATAL DEVELOPMENT / 解剖学报

ABSTRACT

The pancreatic polypeptide (PP) cells of rat pancreatic islets were demonstrated by immunocytochemical method. The distribution and morphology of PP cells were investigated in order to observe their changes during postnatal development. At the lst day and 7th day of rat after birth, the PP cells of islets were different from that in adult, the processes of PP cells were not evident, and the immunoreactivity was weaker. In addition, the PP cells were also presented in the duodenum epithtlium. After 18th day, the distribution and morphology of the PP cells did not show obvious difference from that in adult. The percentage of PP cells of islets was less in lst day, and approximated to adult level in 18th day, and over adult level in 28 th day. The above changes of percentage of the PP cells showed mainly in islets in the head of pancreas. The changes of volume density and numerical density per area corresponded with the changes of percentage of the PP cells. Immunoelectron microscopic study showed that the secretory granules (SGs) and gold la belled particles on the SGs of the PP cells in 7th day were less than that in 28th day and adult. Based upon the morphology of the SGs, the PP cells can be classified into two types. The type Ⅰ cells contained SGs with medium electron density or empty-like cores, and larger SGs were more. The type Ⅱ cells contained SGs with lower electron density cores, and small SGs were more. The gold labelled particles in SGs in the type Ⅰ were more than that in the type Ⅱ. The results suggest that the PP cells of rat islets continue to change after birth.