The Neuron Doctrine
The Neuron Doctrine is a concept that led scientists to the realization that the brain consists of many specialized regions and cells. However, during the process, scientists had to overcome obstacles such as the minute size of the cell, the jello-like consistency of brain tissue, and the similar cream- colored pigmentation of tissue cells. Advances in technology over the years, though, helped to solve these problems: the development of the compound microscope, the discovery of how to harden, or “fix,” tissues by immersing them in formaldehyde, the creation of a special device called a microtome to make very thin slices, the introduction of stains (Nissl stain) that could selectively color some, but not all, parts of the cell in brain tissue,
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He discovered that by soaking brain tissue in a silver chromate solution, now called the Golgi stain, a small percentage of neurons became darkly colored in their entirety. The Golgi stain shows that neurons have at least two distinguishable parts: a central region that contain the cell nucleus (cell body or soma), and numerous thin tubes (neurites) that radiate away from the central region. The neurons consisted of two types: axons and dendrites. Axons were recognized by histologists of the day to act like “wires” that carry the output of the neurons while dendrites were thought to act as the antennae of the neuron to receive incoming signals, or input. However, Santiago Ramon y Cajal, after learning about Golgi’s method in 1888, used the Golgi stain to work out the circuitry of many regions of the brain. While Golgi championed the view that the neurites of different cells are fused together to form a continuous reticulum, or network, similar to the arteries and veins of the circulatory system, Cajal argued forcefully that the neurites of different neurons are not continuous with one another and must communicate by contact, not continuity. Cajal’s contribution to neuroscience led to the ideas of the neuron doctrine. It was the scientific proof by the electron microscope 50 years later, though, that proved that the neurites of different neurons are not continuous with one another, but must be the individual
He discovered that by soaking brain tissue in a silver chromate solution, now called the Golgi stain, a small percentage of neurons became darkly colored in their entirety. The Golgi stain shows that neurons have at least two distinguishable parts: a central region that contain the cell nucleus (cell body or soma), and numerous thin tubes (neurites) that radiate away from the central region. The neurons consisted of two types: axons and dendrites. Axons were recognized by histologists of the day to act like “wires” that carry the output of the neurons while dendrites were thought to act as the antennae of the neuron to receive incoming signals, or input. However, Santiago Ramon y Cajal, after learning about Golgi’s method in 1888, used the Golgi stain to work out the circuitry of many regions of the brain. While Golgi championed the view that the neurites of different cells are fused together to form a continuous reticulum, or network, similar to the arteries and veins of the circulatory system, Cajal argued forcefully that the neurites of different neurons are not continuous with one another and must communicate by contact, not continuity. Cajal’s contribution to neuroscience led to the ideas of the neuron doctrine. It was the scientific proof by the electron microscope 50 years later, though, that proved that the neurites of different neurons are not continuous with one another, but must be the individual