Myelination in the chorda tympani of the postnatal rat: a quantitative electron microscope study.
We determined the course of myelination of the chorda tympani in rats aged from 4- to 30-days-old, the interval of the most rapid developmental changes in neurophysiological taste responses and behavioral discrimination among chemical stimuli. The overall number of axons in rats aged from 16- to 30-days-old and in mature 120-day-old animals were the same and averaged 1,500. By 30 days, rats had 80% of the total number of myelinated axons observed in adults, but the average thickness of the myelin sheath per neuron and the proportion of the total cross-sectional area that were only about 60% of adult values. Observed increases in myelination closely parallel decreasing response latencies of single chorda tympani fibers to tongue stimulation with salts.
D000818:Animals; D002814:Chorda Tympani Nerve / Q000254:growth & development* / Q000648:ultrastructure; D005260:Female; D008854:Microscopy, Electron; D009186:Myelin Sheath / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013650:Taste Buds / Q000254:growth & development