The Studies Of The Fine-structure Of Hippocampal CA1 Axospinous Synapses In Mouse

Dendritic spines were first described at the end of the 19th century by Ramon y Cajal. Cajal proposed that these small protrusions emerging from the dendrites of many neurons were sites of neuronal contact and suggested that changes in spine morphology might affect the activity of neurons. From then on, studies based on both light and electro microscopy have confirmed that spines are indeed sites of synaptic input, with over 90% of excitatory input ending on dendritic spines, and that spines are one of the most important stu- ctrure of the axospinous synapses. There fore, the density and morphology of dendritic spines at a given locus could be interpreted as a readout of the num- ber and state of potentiation of a population of synapses. Since its conception, this dogma has been supported by indirect, correlative and anecdotal obser- vations; for instance, an enriched environment enhances spine for mation, and men- tally retarded children express immature spines. As excitatory synapses reside on spine heads, and synapses have been shown to express plastic properties similar to those that are thought to take place during learning and the formation of memory, it was natural to assume that spine morphology is correlated with memory storage.Many studies have showed that the hippocampal CA1is associated with learning and memorying. So we observed the fine-structure of hippocampal CA1 axospinous synapses of C57BL/6 mouse, analyzed the construction features, described the correlation characteristic of the axospinous synapses of the normal,aged and FMR1 knock-out mouse, and provided some neuro- anatomic data for the studies of the plasticity of dendritic spines.Results of the studies as follow:1 Correlations of the spine head with its postsynaptic density of axopinous synapses in mouse CA1...