The suprachiasmatic nucleus (SCN) is the
primary circadian pacemaker in mammals.
Ralph and colleagues/14/provided recent new
evidence for this by transplanting SCNs between
golden hamsters with different genetically
determined periods and producing circadian
rhythmsof running wheel activity with periods
characteristic of the donor. We have extended
these studies in order to evaluate the age range
of donor tissue that can be used for transplantation.
SCN of hamsters from embryonic day 11
through postnatal day 12 can serve as functional
grafts to restore rhythmicity to arrhythmic SCN
lesioned animals. The time between SCN transplantation
and onset of rhythmicity does not
depend on the age of the donor. The presence of
patches containing vasoactive intestinal peptide
(VIP) immunoreactive cells is a good indicator
of graft success, while its absence is correlated
with a lack of transplant effect. The 18 day span
during which SCN tissue can be harvested for
transplantation should expand the uses to which
this technique can be put. Our results also
suggest that it would be advantageous to
examine the age range of neural tissue that ca’n
be used in other transplantation models