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How did Camillo Golgi use the black reaction to study nerve cells?

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Diagram of the Golgi apparatus showing its stacked, curved membranes with labeled parts including cisternae, cis face, trans face, lumen, and various vesicles involved in cellular transport and secretion. — Golgi apparatus A membrane-bound organelle of eukaryotic cells, the Golgi apparatus is made up of a series of flattened, stacked pouches called cisternae that function as a series of compartments that progressively refine and direct cellular products to their proper destinations. .

To study nerve cells, Camillo Golgi developed a staining technique known as the reazione nera, or "black reaction" (now called the Golgi stain).

In this process, he fixed nervous tissue with potassium dichromate and then suffused it with silver nitrate. This method was revolutionary because it allowed for the visualization of the fine structure of the nervous system, which was previously difficult to observe clearly. By using this stain, Golgi was able to demonstrate the existence of specific nerve cells—later named Golgi cells—that possess numerous short, branching extensions known as dendrites.12

Furthermore, while examining neurons prepared with his black reaction, Golgi identified an "internal reticular apparatus" within the cells, which is now recognized as the Golgi apparatus. His work provided the foundational evidence that helped establish the nerve cell as the basic structural unit of the nervous system.12