Golgi

Golgi

[gawl-jee]
Golgi, Camillo, 1844-1926, Italian physician, noted as a neurologist and histologist. He shared with Ramón y Cajal the 1906 Nobel Prize in Physiology or Medicine for work on the structure of the nervous system. He introduced (c.1870) a method of staining nerve tissue with silver nitrate that he used (1883) to demonstrate certain nerve cells (Golgi cells) in the central nervous system. He observed (1909) the Golgi apparatus, a part of the cytoplasm distinguishable by special staining and known as the Golgi bodies when in the form of separate particles. He recognized that the three types of malaria are caused by different protozoan organisms. Golgi taught at the Univ. of Pavia from 1875.

Camillo Golgi, 1906.

(born July 7, 1843/44, Corteno, Italy—died Jan. 21, 1926, Pavia) Italian physician and cytologist. He devised a way to stain nerve tissue and with it discovered a neuron, now called the Golgi cell, that has many short, branching extensions (dendrites) and connects other neurons. This led to identification of the neuron as the basic structural unit of the nervous system. He also discovered the Golgi tendon organ (the point at which sensory nerve fibres branch out within a tendon) and the Golgi apparatus (a cell organelle that packages large molecules for transport). He shared a 1906 Nobel Prize with Santiago Ramón y Cajal (b. 1852—d. 1934).

Learn more about Golgi, Camillo with a free trial on Britannica.com.

Camillo Golgi, 1906.

(born July 7, 1843/44, Corteno, Italy—died Jan. 21, 1926, Pavia) Italian physician and cytologist. He devised a way to stain nerve tissue and with it discovered a neuron, now called the Golgi cell, that has many short, branching extensions (dendrites) and connects other neurons. This led to identification of the neuron as the basic structural unit of the nervous system. He also discovered the Golgi tendon organ (the point at which sensory nerve fibres branch out within a tendon) and the Golgi apparatus (a cell organelle that packages large molecules for transport). He shared a 1906 Nobel Prize with Santiago Ramón y Cajal (b. 1852—d. 1934).

Learn more about Golgi, Camillo with a free trial on Britannica.com.

Golgi's method is a nervous tissue staining technique discovered by Italian physician and scientist Camillo Golgi (1843-1926) in 1873. It was initially named the black reaction (la reazione nera) by Golgi, but it became better known as the Golgi stain or method later.

Golgi' staining was famously used by Spanish neuroanatomist Santiago Ramón y Cajal (1852-1934) to discover a number of novel facts about the organization of the nervous system, inspiring the birth of the neuron doctrine.

Mechanism

The cells in nervous tissue are densely packed and little information on their structures and interconnections can be obtained if all the cells are stained. Furthermore, its thin filamentary extensions—the axon and the dendrites—are too slender and transparent to be seen with normal staining techniques. Golgi's method stains a limited number of cells at random in their entirety. The mechanism by which this happens is still largely unknown. Dendrites, as well as the cell soma, are clearly stained in brown and black and can be followed in their entire length, which allowed neuroanatomists to track connections between neurons and to make visible the complex networking structure of many parts of the brain and spinal cord.

Golgi's staining is achieved by impregnating fixed nervous tissue with potassium dichromate and silver nitrate. Cells thus stained are filled by microcrystallization of silver chromate.

Technique

According to SynapseWeb , this is the recipe for Golgi's staining technique:

  1. Immerse a block (approx. 10x5 mm) of formol-fixed (or paraformaldehyde- glutaraldehyde-perfused) brain tissue into a 2% aqueous solution of potassium dichromate for 2 days
  2. Dry the block shortly with filter paper.
  3. Immerse the block into a 2% aqueous solution of silver nitrate for another 2 days.
  4. Cut sections approx. 20-100 µm thick.
  5. Dehydrate quickly in ethanol, clear and mount (e.g., into Depex or Enthalan).

This technique has since been refined to substitute the silver precipitate with gold by immersing the sample in gold chloride then oxalic acid, followed by removal of the silver by sodium thiosulphate. This preserves a greater degree of fine structure with the ultrastructural details marked by small particles of gold.

Quote

Cajal said of the Golgi method:

I expressed the surprise which I experienced upon seeing with my own eyes the wonderful revelatory powers of the chrome-silver reaction and the absence of any excitement in the scientific world aroused by its discovery.
Recuerdos de mi vida, Vol. 2, Historia de mi labor científica. Madrid: Moya, 1917, p. 76.

Notes

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