The Dopaminergic Innervation Of The Brain Stem And Spinal Cord: An Anatomical Study on the Distribution of the Neurotransmitter Dopamine and Its D2 Receptor

Until the first half of the 19th century, the anatomy of the nervous system was studied mainly by means of macroscopic methods, like dissection, while microscopy was hampered by the lack of adequate staining techniques. However, when reliable fixation and staining techniques (like the Weigert and Golgi stains and the silver impregnation technique for degenerating fibers) became available, the knowledge of the nervous system rapidly increased. Since then a multitude of new research methods employed by an ever increasing number of scientists involved in studying the nervous system, have led to a rapid progress in our knowledge and - to some extent - our understanding of the nervous system. The classical anatomical studies and especially the findings of Ramon y Cajal (1909), the great advocate of the neuron theory, have laid the foundation of our present knowledge of the nervous system. Cytoarchitectonic studies of this period, made a big impact on neuroscience and served as the basis of the nomenclature of the central nervous system as it is still used today. Data on the chemical identity and the specific function of (groups of) nerve cells became available more recently. Often the data complemented, but sometimes it conflicted with, the cytoarchitecture based subdivisions of the brain. This induced the introduction of alternative nomenclatures, not based on cytoarchitecture, but on pharmacological or functional characteristics. This thesis, which describes an anatomical study of the dopamine innervation of the brain stem and spinal cord and one of the receptors involved, i.e. of a chemically identified system characterized by containing the transmitter dopamine, reflects some of these great changes, which transformed classical neuroanatomy into a dynamic, functional science. In this chapter the subject will be introduced by a short description of the anatomy of the spinal cord and the brainstem, followed by a description of the chemical anatomy of the nervous system, with the main emphasis on the doparninergic system and its receptors. Subsequently, we will provide insight into the scope of this thesis.