In the leech, synapse regeneration in adults and synapse formation during embryonic development can be studied in single, identifiable cells that make precise connections with their targets. Certain cellular components, such as synaptic targets and glia, were selectively destroyed to study how the regenerating axons locate their targets, what triggers axons to start growing and what stops them....

The Leech lattice is the exceptional lattice in dimension 24. Soon after its discovery by Leech [9], it was conjectured that it is extremal for several geometric problems in R: the kissing number problem, the sphere packing problem, and the sphere covering problem. In 1979, Odlyzko and Sloane and independently Levenshtein solved the kissing number problem in dimension 24 by showing that the Lee...

The Retzius neuron from the leech, growing in culture on the plant lectin concanavalin A as substrate, produces broad flat growth cones and thick bundles of processes. The same cell extends fine straight processes with numerous branches when grown on a laminin-like substrate extracted from leech central nervous system extracellular matrix, referred to as "leech laminin extract." Cells growing o...