238 GUTH
of the synapse provided the first unequivocal proof of cellular discon
tinuity at the synapse, the concept which was a cornerstone of the
“neuron doctrine” for which Santiago Ramón y Cajal had received the
Nobel Prize some 50 years earlier. In other papers, Palay played a leading
role in resolving the controversy over the ultrastructural identification of
astrocytes and oligodendrocytes.^11 These findings provided baseline
information essential for many subsequent biochemical and physiologi
cal investigations on neurons and neuroglia.Cammermeyer
Cammermeyer was an experimental neuropathologist and a very astute
microscopist. He spent much of his first decade at the NIH investigating
the effects of various fixatives (administered by immersion or perfusion)
on brain volume in an effort to eliminate the swelling or shrinkage that
occurs during histological procedures for preparing tissues for light micro
scopy. For this purpose, he made painstaking measurements of swelling
and shrinkage at each stage of the fixing, dehydrating, embedding, sec
tioning and staining steps. These studies required expert microscopical
analysis. Cammermeyer’s scientific expertise and helpful attitude made
him an important resource for other scientists in the laboratory. As an
example, he called me into his laboratory one day and showed me an
autoradiograph made with tritiated thymidine which clearly revealed
silver grains over the nucleus of a large neuron. I was dumbfounded to
see this evidence of a dividing adult neuron. Before I could say anything
that might betray my ignorance, he told me to focus up and down with
the fine adjustment. All at once it became apparent that the silver grains
were not over the neuron’s nucleus but over that of a glial cell located
beneath the neuron. I learned that day why his motto was “one must
always be cautious,” and how much pleasure can be derived from teaching
others to enjoy the art, craft, and science of histology and histopathology.Rasmussen
During the 1940s, Rasmussen had discovered the olivocochlear bundle,
an efferent pathway within the auditory system. For a long while the
very existence of this pathway was disputed, but during his years at the
NIH the issue was resolved in his favor. Its function was eventually