| Genomics and gene expression information provide us with most if not all building blocks of living organisms. However, the details of function of individual organ systems are only gradually understood, depending on their complexity. We are interested in the architecture and development of the mammalian central nervous system. Knowledge about the number and properties of individual neuronal cell types is constantly accumulating, however neurophysiologic, morphologic and molecular approaches are poorly integrated. In this work, a novel strategy for the genetic tagging and morphological analysis of neuronal cell types is described. Using available as well as newly created knock-in and transgenic mouse lines, the reporter gene Alkaline Phosphatase is induced in individual neurons. The reporter gene labels by a simple and reliable color substrate technique individual cell morphologies, and allows classification of neurons based on morphological criteria. It can be detected in immature, developing neurons, and is expressed in progenitors of neuroblasts in which the reporter has been induced. Neurites projecting over long distances are labeled. Using this novel staining approach, a classification of mouse retinal cell types was derived. Neurons were classified using criteria based on measurements of their neurite arbors. A few novel cell types as well as unreported features of others were uncovered, proving that this technique is a useful addition to the panoply of instruments available for the study of neuronal cell types and their development. |
