Ca. Boillat et al., ULTRASTRUCTURAL-CHANGES IN THE DEEP CORTICAL PYRAMIDAL CELLS OF INFANT RATS WITH INHERITED HYDROCEPHALUS AND THE EFFECT OF SHUNT TREATMENT, Experimental neurology, 147(2), 1997, pp. 377-388
Pathological changes in the cortical gray matter in infantile hydrocep
halus vary with the age at onset and may not be reversible with shunt
treatment, We have used electron microscopy to investigate the sequenc
e of pathological change and the effect of shunt treatment on layer VI
pyramidal cells from infant II-Tx rats with inherited early-onset hyd
rocephalus. Tissue was prepared from the frontal and visual cortex of
control and hydrocephalic rats at 4, 11, and 21 days after birth, toge
ther with al-day rats previously treated with ventriculosubcutaneous s
hunts at 4-5 or 10-11 days after birth. Both cortical regions gave sim
ilar results but the effects were more severe in the visual cortex. In
the early stages of hydrocephalus, the pyramidal cells were in cluste
rs with fewer mature dendrites and less cytoplasmic organization than
those in control rats, and some neuronal processes were vacuolated. In
intermediate hydrocephalus the changes were more severe, with vacuola
ted cytoplasm, fewer cytoplasmic organelles, frequent swollen processe
s, and infrequent synapses. In advanced hydrocephalus at 21 days, many
neurons showed degenerative changes, with edematous Golgi and dilated
endoplasmic reticulum, distorted mitochondria, and single ribosomes.
The neuropil contained many spongy areas with distended profiles. Shun
t treatment prevented most of the changes if carried out at 4 days. Sh
unt treatment at 11 days also gave a dramatic recovery at the cellular
level, but there were more immature pyramidal cells and edematous pro
cesses in the neuropil than in the 4-day-treated rats. The changes in
hydrocephalus are consistent with progressive neuronal damage, which i
s largely prevented by early shunt treatment. (C) 1997 Academic Press.