In the present study, the monoclonal antibody Alz-50 has been used to
determine and compare the immunohistochemical localization of phosphor
ylated tau proteins in the developing and normal adult spinal cord. At
all stages of fetal life Alz-50 fiber immunoreactivity was observed i
n the dorsal roots, in the dorsal and dorsolateral funiculi, and in re
stricted regions of the dorsal horn. Alz-50 immunoreactivity was also
demonstrated in the dorsal root ganglion neurons. In the adult spinal
cord a consistent pattern of Alz-50 fiber immunoreactivity was localiz
ed in the superficial layers of the dorsal horn (lamina I and II) but
not in dorsal and dorsolateral funiculi and in the dorsal root ganglio
n. Comparable results in fetal specimens have been obtained employing
PHF-1, a monoclonal antibody generated against paired helical filament
proteins from Alzheimer brains,while no significant immunostaining fo
r PHF-1 was observed in the adult spinal cord. In addition, the staini
ng with monoclonal and polyclonal anti-tau antibodies overlapped with
that of Alz-50. The transient, selective pattern of Alz-50 and PHF-1 i
mmunoreactivity may disclose some relevant functions of tau proteins d
uring somatosensory pathway development.