A pair of achromatic lenses L2 ( f = 100 mm) and 元 ( f = 50) form a 4F configuration to relay the image at A to the image sensor. The imaging signal collected by the microscope objective, OBJ, is focused by a doublet achromatic lens (L1, f = 200 mm) to form a conjugate imaging plane where a mechanical pupil (A) is placed to control the aperture size. A Hamamatsu ORCA-Flash 2.8 CMOS camera (Hamamatsu Photonics, Hamamatsu, Japan) with 1920 × 1440 pixels is used as the image sensor to acquire bright-field microscopic images. 5, a high-power white LED light source is placed above the sample stage of the microscope in a transmission configuration to provide bright-field illumination.
The position detection path and the laser-trapping beam are built around a wide-field microscope. Indeed, the definitive disproof of the reticular doctrine and confirmation of the neuron doctrine had to await the electron microscope. When they shared the Nobel Prize in 1906, Golgi and Cajal's addresses were violent attacks on one another, and the reticular concept did not entirely disappear for a few more decades. This extension of cell theory to the nervous system is known as the “neuron doctrine.” Cajal further demonstrated that neurons come in a great variety of specific shapes that are characteristic of their location and often constant from animal to animal and species to species. Yet, by using Golgi's silver stain the great Spanish anatomist Salvadore Ramón y Cajal (1852–1936) was able to demonstrate that each nerve cell with its dendrites and axon is an independent unit.
Gerlach (1820–96) is usually considered the founder of this reticular doctrine, and Camillo Golgi (1844–1920) its most famous advocate. Nerve cells were thought to be nodes of this reticular structure and the fibers originating from them to anastomose completely. Even after RA Von Kolliker (1817–1905) demonstrated that nerve fibers came from nerve cells and OFK Deiters (1834–63) distinguished axons from dendrites, the nervous system was thought to consist of an interconnected network.
Until then, and even somewhat after, nerves were considered to be hollow as Galen had suggested, gray matter was made up of “globules,” and the relationship between the fibers of white matter and globules was unclear.Īlthough MJ Schleiden in 1838 pointed out that cells were the basic unit of plant life and T Schwann in 1839 extended this idea to animals, the nervous system resisted an interpretation in terms of their cell theory for at least another 60–70 years. Gross, in Reference Module in Neuroscience and Biobehavioral Psychology, 2017 From Globules to NeuronsĬells were first described (in plants) by Robert Hooke (1635–1703) and in what he called nerve fibers by Anton van Leeuwenhoek (1632–1723), but it was not until the development of achromatic lenses and methods of embedding and staining in the middle of the 19th century that the study of the fine structure of the nervous system could begin.
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