Journal of Neuroscience, Vol 2, 503-512, Copyright © 1982 by Society for Neuroscience
Patterns and kinetics of neurite extension from sympathetic neurons in culture are age dependent
V Argiro and MI Johnson
Long term (2- to 3-week) cultures of superior cervical ganglia (SCG) were
established from rats and rat embryos ranging in age from 15 days of
gestation (E15) to 279 days postnatal (P279). Cultures were grown on a
collagen substratum and fed a serum-containing medium with added nerve
growth factor. Radial outgrowth of neurites was measured as a function of
time for up to 2 to 3 weeks. Computer-aided analysis generated estimates of
onset time, initial rate, and subsequent changes in the rate of growth of
these neurites. The explants from perinatal rats showed the fastest growth
onset time (5 to 13 hr), fastest initial rate of growth (370 to 660
microns/d), and a decline in growth rate during the first 2 weeks in
culture. The outgrowth from these perinatal explants was composed of many
small fascicles. Neurites from the prenatal explants (E15 to E20) began to
grow within 22 hr in vitro. Their rate of growth was lower initially (150
to 300 microns/d) but increased to equal the perinatal explant initial rate
before again falling to an intermediate level (200 to 300 microns/d). The
outgrowth from prenatal explants contained fewer larger fascicles.
Postnatal explants had low initial rates of growth (70 to 176 microns/d)
but exhibited an increasing growth rate in vitro, again approaching an
intermediate rate of 200 to 250 microns/d after 2 to 3 weeks. Neurite
outgrowth from the postnatal explants was delayed by an amount roughly
correlated with the age of the animal advancing postnatal age but reached
an asymptote of about 50 to 150 microns/d at about P30. The outgrowth was
initially sparse but became denser with time in culture. Thus, in a culture
system in which medium composition and growth substratum are held constant,
marked differences can be observed in pattern, latency, initial rate, and
subsequent changes in rate of neurite extension among SCG explants from
different ages of rats and rat embryos.