Exocytotic release of neurotransmitters from nerve fibers in the endocrine pancreas (Brockmann body) of the teleost, Takifugu niphobles.

Exocytotic release of neurotransmitters was ultrastructurally investigated in the endocrine pancreas (Brockmann body) of the teleost, Takifugu niphobles. Exocytotic figures of large cored vesicles were found not only on the surface of nerve fibers facing the endocrine cells directly, but also on their surface facing the space of connective tissues including the blood capillaries. The results indicate that some 'neurotransmitters' are released non-synaptically in the endocrine pancreas and that some 'neurotransmitters' may enter the blood stream as 'neurosecretory hormones.'