The Journal of physiology
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The Journal of physiology · Jun 1983
Neuromuscular transmission and correlative morphology in young and old mice.
1. Age changes in spontaneous and evoked transmitter release, in receptor number and in ultrastructure at the neuromuscular junction were studied in the CBF-1 mouse strain, which stays physically active and relatively free of organ pathology into advanced age.2. Spontaneous miniature end-plate potentials (m.e.p.p.s) were recorded in the following young (8-12 months) and old (29-33 months) mouse muscles: extensor digitorum longus (e.d.l.), soleus (sol.), gluteus maximus (g.m.), diaphragm (diaph.) and extensor digitorum communis (e.d.c.).3. ⋯ Since no evidence of denervation was found by physiological criteria, it is concluded that in 34-month mice, nerve terminals withdraw from some synaptic gutters but do not abandon any junction entirely. The large presynaptic ultrastructural changes contrast with the physiological data showing no deficit and even increases in transmitter release. Therefore, under these conditions, these profound structural changes are either not functionally significant or are well compensated.