Discovering the Structure of Nerve Tissue: Part 2: Gabriel Valentin, Robert Remak, and Jan Evangelista Purkyně

Marcello Malpighi: the nervous system under a microscope

The longstanding study of gross anatomy experienced a considerable improvement with the advent of the microscope in the early 17th century. The representative personality of this new era certainly was Marcello Malpighi, seen as "founder of microscopic anatomy". He studied, with a rudimentary compound microscope, numerous tissues and organs of several classes of animals, as well as plants. He described, for the first time, the microscopic structure of the nervous system, identifying in the gray matter of its various levels minute elements he took as "glands". It should be reminded that the concept of "cell" (and "nerve cell") was unknown at his time. Many researchers followed, performing microscopic studies, but without better results, and Malpighi's view was maintained until the beginning of the 19th century, when new histological processing and staining techniques appeared, as well as improved microscopes.

An Early History of Neuroglial Research: Personalities

Neuroscience, like most other divisions of natural philosophy, emerged in the Hellenistic world following the first experimental discoveries of the nerves connecting the brain with the body. The first fundamental doctrine on brain function highlighted the role for a specific substance, pneuma, which appeared as a substrate for brain function and, being transported through the hollow nerves, operated the peripheral organs. A paradigm shift occurred in 17th century when brain function was relocated to the grey matter. Beginning from the end of the 18th century, the existence of active and passive portions of the nervous tissue were postulated. The passive part of the nervous tissue has been further conceptualised by Rudolf Virchow, who introduced the notion of neuroglia as a connective tissue of the brain and the spinal cord. During the second half of the 19th century, the cellular architecture of the brain was been extensively studied, which led to an in-depth morphological characterisation of multiple cell types, including a detailed description of the neuroglia. Here, we present the views and discoveries of the main personalities of early neuroglial research.

Jan Evangelista Purkyně (1787-1869) and his instruments for microscopic research in the field of neuroscience

The findings obtained by the famous nineteenth-century Czech scientist Jan Evangelista Purkyně (1787-1869) in the field of microscopic structure of animal and human tissues, including the brain, spinal cord, and nerves, have already been described in depth in a number of older and newer publications. The present article contains an overview of the instruments and tools that Purkyně and his assistants used for microscopic research of tissue histology. Some of these instruments were developed either by Purkyně alone, such as the microtomic compressor, or together with his assistant Adolph Oschatz, such as the microtome. A brief overview of the development of the cutting engines suggests that the first microtome, a prototype of modern sliding microtomes, was designed and constructed under the supervision of Purkyně at the Institute of Physiology in Wrocław. Purkyně and his assistants, thus, not only obtained important findings of animal and human nervous and other tissues but also substantially contributed to the development of instruments and tools for their study, a fact often forgotten today.

Vincenc Alexandr Bohdálek (1801-1883): Czech anatomist and neuroscientist of the nineteenth century

Vincenc Alexandr Bohdálek (Vincenz Alexander Bochdalek) was a well-known anatomist and pathologist in the nineteenth century. Today, however, his name is all but forgotten. Bohdálek described a number of anatomical structures; some of them became eponyms. Unfortunately, his findings concerning the innervation of the eye, upper jaw, hard palate, auditory system, and meninges are little known today. This current overview is based on available archival sources and provides an insight into his results in the field of nervous system research, which account for almost half his work. Bohdálek can clearly be considered a pioneer in the field we now call functional anatomy, as he tried to find a physiological explanation for the anatomical and pathological findings he observed. The work and results of this truly outstanding neuroscientist of his time are thus again available to current and future generations of neuroscientists and neuroanatomists.

Discovering the structure of nerve tissue: Part 3: From Jan Evangelista Purkyně to Ludwig Mauthner

The previous works of Purkyně, Valentin, and Remak showed that the central and peripheral nervous systems contained not only nerve fibers but also cellular elements. The use of microscopes and new fixation techniques enabled them to accurately obtain data on the structure of nerve tissue and consequently in many European universities microscopes started to become widely used in histological and morphological studies. The present review summarizes important discoveries concerning the structure of neural tissue, mostly from vertebrates, during the period from 1838 to 1865. This review describes the discoveries of famous as well as less well-known scholars of the time, who contributed significantly to current understandings about the structure of neural tissue. The period is characterized by the first descriptions of different types of nerve cells and the first attempts of a cytoarchitectonic description of the spinal cord and brain. During the same time, the concept of a neuroglial tissue was introduced, first as a tissue for "gluing" nerve fibers, cells, and blood capillaries into one unit, but later some glial cells were described for the first time. Questions arose as to whether or not cells in ganglia and the central nervous system had the same morphological and functional properties, and whether nerve fibers and cell bodies were interconnected. Microscopic techniques started to be used for the examination of physiological as well as pathological nerve tissues. The overall state of knowledge was just a step away from the emergence of the concept of neurons and glial cells.