During the pupal stage of moths, a mass of connective tissue develops on the dorsal side of the abdominal nerve cord . The cells, which secrete the fibrous matrix, are originally close together, but as they secrete the matrix, they are pushed apart, with a corresponding decrease in their size . As the process proceeds, it was noticed that there is a gradual development of desmosomes where the membranes of two cells remain adjacent, and of hemidesmosomes where cell membranes adjoin the fibrous tissue. The desmosomes and hemidesmosomes are similar in structure and are of a type which, at present, appears to be confined to insects and other arthropods. Desmosomes are found between many different cells, for example, between the blood cells forming a capsule around