In the early 60s, Giorgio Gabella, a senior lecturer in Anatomy, become my supervisor in Torino. He was stern and serious, but intellectually sharp. Underneath was a genuinely warm person hidden under strong social restraints. It is one of my most rewarding experiences to have re-established close and warm contacts with Giorgio in recent times.
As an anatomy student, I was immediately attracted by the beautiful geometrical architecture of the plexuses which could be studied ‘in toto’ (whole) in flat preparations consisting of the full thickness of the gut wall. My first task was to stain a segment of guinea pig small intestine with the established method of silver impregnation. This classic staining for neurons was developed in the late 19th Century by another Nobel prize-winner, Camillo Golgi. Being an amateur photographer, he used silver salts to develop films. His method was later used extensively by Spaniard Santiago Ramon y Cajal, to describe systematically the histology of the nervous system of many living organisms. In 1906, both were awarded Nobel prizes in Medicine, although for opposing hypotheses!
Golgi claimed that the nervous system consisted of a continuous net of nerve elements (a reticular theory), whereas Ramon y Cajal maintained that separate nerve cells made up the nervous system. His neuron theory was eventually proven correct. His arguments were based on studies of development and degeneration. He was aware of the experiments of Charles Sherrington who, at the turn of the 20th Century, achieved accurate timing of spinal reflexes, leading to the conclusion that there must have been a gap (synapse) between input and output neurons.
In my first preparations of the intestinal plexuses with silver impregnation, only a subset of nerve cells stained. Golgi’s method was an incomplete and unsatisfactory way of visualising the full complexity of the plexuses. Many decades later, work on the immunohistochemistry of neurofilaments revealed that the partial staining was due to the fact that not all neurons contain the specific class of neurofilament which is impregnated by silver.
One of Marcello’s first attempts to visualise nerve cells in the wall of the intestine, using a method developed in the late 19th century. Only a few nerve cell bodies and processes were stained.