The vascular system of principal islets: semithin-section studies in teleosts fixed by perfusion

The angioarchitecture of clearly zonated principal islets (central B-cell and peripheral A-cell region) from teleosts has been analyzed in five islets following perfusion fixation and serial sectioning. In contrast to the similar cell-type distribution in the species studied (Gadus morrhua , Myoxocephalus scorpius , Agonus cataphractus , Limanda limanda ) there were three different types of vasculature characterized by centripetal blood flow, centrifugal blood flow, or an intermediate type. The vascular pattern (and the development of the organ capsule) showed inter- and even intraspecies differences. It is suggested that differences in angioarchitecture reflect individually variable interactions of exocrine and endocrine tissue during organogenesis rather than mutual cell-type control via the vascular system.