Drawing by Camillo Golgi of a hippocampus stained with the silver nitrate method

Drawing of a Purkinje cell in the cerebellum cortex done by Santiago Ramón y Cajal, clearly demonstrating the power of Golgi's staining method to reveal fine detail

A human neocortical pyramidal neuron stained via Golgi technique. The hippocampus is a part of the Forebrain, located in the medial Temporal lobe. For the cells of the Electrical conduction system of the heart, see Purkinje fibers Purkinje cells (or Purkinje neurons) are a class of The cerebellum ( Latin: "little brain" is a region of the Brain that plays an important role in the integration of sensory perception The cerebellum ( Latin: "little brain" is a region of the Brain that plays an important role in the integration of sensory perception A pyramidal cell (or pyramidal neuron, or projection neuron) is a multipolar Neuron located in the Hippocampus and Cerebral Notice the apical dendrite extending vertically above the soma and the numerous basal dendrites radiating laterally from the base of the cell body.

Golgi's method is a nervous tissue staining technique discovered by Italian physician and scientist Camillo Golgi (1843-1926) in 1873. Nervous tissue is the fourth major class of Vertebrate tissue. Staining is an auxiliary Technique used in Microscopy to enhance contrast in the microscopic image Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest A physician, medical practitioner or medical doctor who practices Medicine, and is concerned with maintaining or restoring human Health A scientist, in the broadest sense refers to any person that engages in a systematic activity to acquire Knowledge or an individual that engages in such practices Camillo Golgi ( July 7, 1843 &ndash January 21, 1926) was an Italian Physician and Scientist. Year 1873 ( MDCCCLXXIII) was a Common year starting on Wednesday (link will display the full calendar of the Gregorian calendar (or a Common 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. Spain () or the Kingdom of Spain (Reino de España is a country located mostly in southwestern Europe on the Iberian Peninsula. Neuroanatomy is the science for localizing function in the Human brain. Santiago Ramón y Cajal ( May 1 1852 &ndash October 17 1934) was a Spanish histologist, Physician, and The neuron doctrine is the now fundamental idea that Neurons are the basic structural and functional units of the Nervous system.

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. An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell Dendrites (from Greek δένδρον déndron, “tree” are the branched projections of a Neuron that act to conduct the electrochemical 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. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain The spinal cord is a long thin tubular bundle of Nerves that is an extension of the Central nervous system from the brain and is enclosed in and protected

Golgi's staining is achieved by impregnating fixed nervous tissue with potassium dichromate and silver nitrate. Potassium dichromate, K2Cr2O7 is a common inorganic chemical reagent most commonly used as an Oxidizing agent in various laboratory Silver nitrate also known as lunar caustic is a soluble Chemical compound with Chemical formula Ag[[Nitrogen N]] O 3 Cells thus stained are filled by microcrystallization of silver chromate. Crystallization is the (natural or artificial process of formation of solid Crystals precipitating from a homogeneous --> identical Solution Silver chromate (Ag2CrO4 is a brown-red Monoclinic crystal and is a chemical precursor to modern Photography.

Technique

According to SynapseWeb [1], 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. Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl Paraformaldehyde, also known as polyoxymethylene, is the Condensation product of Formaldehyde with a typical chain length of 8 - 100 units Glutaraldehyde is a colorless liquid with a pungent odor used to sterilize medical and dental equipment Potassium dichromate, K2Cr2O7 is a common inorganic chemical reagent most commonly used as an Oxidizing agent in various laboratory Filter paper is a semi-permeable Paper barrier placed Perpendicular to a liquid flow
3. Immerse the block into a 2% aqueous solution of silver nitrate for another 2 days. Silver nitrate also known as lunar caustic is a soluble Chemical compound with Chemical formula Ag[[Nitrogen N]] O 3
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. [2]

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.

See also

• Silver staining

External links

• Photomicrograph of a cortex cell stained with Golgi's. Silver staining is the use of Silver to stain Histologic sections This kind of staining is important especially to show Proteins (for example type III IHC Image Gallery.
• Golgi impregnations. Images of the brain of flies.
• Visualization of dendritic spines using Golgi Method. SynapseWeb. Includes a time-lapse study of Golgi impregnation.
• Berrebi, Albert: Cell Biology of Neurons: Structure and Methods of Study. (in PDF)
• Valverde, Facundo. Golgi Atlas of the Post Natal Mouse Brain.
• BrainMaps at UCDavis Golgi-stained neurons