From phylogeny into ontogeny with Claes Hellerström

My research career started with snakes. For a year, from 1965 to 1966, Claes Hellerstr€ om and I worked together in herpetology (the branch of zoology that deals with amphibians, including frogs, toads, and reptiles). We joined forces with an SAS pilot, Captain Florin, who, between the flights to Los Angeles, was chairman of the Uppsala Herpetological Society. In his spare time, he collected rattlesnakes in the Californian deserts, transported them in the cockpit of his plane, and delivered them to us. Our second supplier was a herpetologist located close to Arlanda airport. Vipers on demand—as we needed snakes, he went out into the forest and collected them for us. Why snakes? In histology textbooks from the 1950s, the pancreatic islets were described as being composed of three cell types: alpha (A), beta (B), and delta (D). It had long been known that the beta cells produce insulin. Although a substance with hyperglycemic properties—glucagon—had been detected in pancreatic extracts as early as 1923 (1), it was not until the early 1950s that it was discovered that alpha cells produce glucagon (2). In 1960, Claes Hellerstr€ om and his PhD supervisor Bo Hellman described a silver impregnation technique that made it possible to distinguish between two types of alpha cells, which they termed A1 and A2 cells (3,4). They made the case that the A2 cells were the glucagon producers. The question then remained: what is the function of the A1 cells? This is where phylogenetic studies, including those on reptiles, came into the picture.