5
THE ENDOCRINE PANCREAS
AUGUST EPPLE
I. Introduction . . . . . . . . . . . . 275
11. The Phylogeny of the Endocrine Pancreas of Fishes . . . . 277
A. The Occurrence and Action of Insulin in Invertebrates . . 277
B. General Trends in Pancreas Evolution . . . . . . 278
C. Cytological Characteristics and Nomenclature of the Islet Cells . 279
D. ‘Comparative Islet Histophysiology of the Fishes . . . . 279
E. Variations in Structure and in Biological and Immunological
Activities of the Islet Hormones in Fishes . . . . . 287
111. Function and Metabolism of the Islet Cells in Fishes . . . 291
A. Synthesis, Storage, and Release of Insulin . . . . . 291
B. Metabolic Pathways of the Islet Tissue . . . . . . 293
C. Enzymes of the Islet Tissue . . . . . . . . 293
IV. The Physiological Role of the Islets in Fishes . . . . . 296
A. Islet Changes under Normal Conditions
. . . . . 296
B. Experimental Islet Studies . . . . . . . . 297
C. Effects of Exogenous Islet Hormones in Fishes . . . . 302
V.Summary
. . . . . . . . . . . . 305
References
. . . . . . . . . . . . . 307
I. INTRODUCTION
In the history of islet research the fishes play an important role. In
1846, Stannius and Brockmann described the Brockmann bodies in teleosts
(see Section 11, D, 5, c). An internal secretion of the pancreas, however,
was not the issue of these days. About 20 years later, when Langerhans
(1869) discovered the islets in the rabbit pancreas, he felt that he even
had “to refrain from a hypothesis on the character and value of our cells.”
When again Langerhans (1873) found the islet tissue in ammocoetes, he
considered it as “the (exocrine) pancreas” of this animal. After Diamare
275