The reinnervation pattern of crural pacinian corpuscles was examined b
y light and electron microscopy in eight adult cats of both sexes 3-18
months after sciatic nerve crush. Normal pacinian corpuscles are each
supplied with a single myelinated axon and a single cylindrical axon
terminal which may branch in the distal part of the inner core. Reinne
rvation of these vibroreceptors was very satisfactory after sciatic ne
rve crush: in a sample of 68 corpuscles examined 3-18 months after the
operation, 92.6% were found reinnervated, while only 7.4% remained de
nervated. At the nerve entry, 84.2% of the reinnervated corpuscles wer
e supplied with a single myelinated axon, while 15.8% received two mye
linated axons; some of the axons branched before or after entering the
inner core. Near the mid-level of the inner core, 60.3% of 63 reinner
vated corpuscles were innervated with a single axon terminal, 22.2% we
re biterminal, while 17.5% had three or more terminals. Regenerated ax
on terminals induced the formation of thin lamellar layers in the axia
l region of the original core and, exceptionally, also at the outer as
pect of the original core. In monoterminal corpuscles, the shape and u
ltrastructure of regenerated endings resembled those of normal control
s, whereas in multiterminal corpuscles their shape and profiles were v
ariable. In contrast to previous reports, reinnervated corpuscles did
not ultimately become monoterminal. On the contrary, the mean number o
f 1.3 terminals found in reinnervated crural corpuscles at 3-5 months
increased to 1.9 terminals per corpuscle 6-18 months after axotomy.