Physological and anatomical study of the developmental process of rat trigeminal sensory branch.

点击翻译按钮获取中文摘要

Primary sensory afferents that connect the peripheral to the central nervous system navigate through a variety of substrates and across considerable distances before making contact with target cells, yet these fibers succeed in conveying the spatial organization of the sensory periphery to central relay nuclei with remarkable precision. Understanding how this mechanism is programd in development has been a major issue in neurobiology for many years.In this study, we showed that one of carbohydrate antigens which has 9-O-acetylated GD3-like structure might be involved in the fasciculation of nerve fibers which innervate whiskers in the same portion. The above molecule might be working as a recognition molecule for sensory nerves to distinguish itself from motor nerves when sensory and moter nerves travell together in the periphery.In the tigeminal nuclei where tigeminal primary afferents terminate, the barrel structure is formed after birth. In this perinatal period (E19-PO) of rat, the terminal arborization of fibers from different branches of the tigeminal nerve (maxillary vs.mandibular) occupy areas with overlap. The proportion of overlap between these two nerve terminals, however, decreases around perinatal period, suggesting fine pruning begin to take place before birth. After birth, as barrel structure is formed, the territories occupied by two branches of the trigeminal nerve are more clearly separated.In vitro study using co-culture system showed that there must be adhesion molecules which are specific to the tigeminal neurite elongation. We have not identified such molecules yet, however, cells in the embryonic skin tissue express molecules with more affinity for tigeminal neurites than that are expressed in retinal cells.