Examination of the inferior olivary complex at both the light and electron microscopic levels has revealed a consistent sparing of neurons within the nucleus beta, the genu of the principal nucleus and the caudal portion of the medial accessory olive following long-term (120 days) 3-AP treatment. 
In the rat, the highest concentration was observed in the dorsal lamella of the principal nucleus and in guinea pig ventral lamella.
Enkephalin-like immunoreactivity was found in the medial and dorsal accessory nuclei, but was sparse in the principal nucleus.
Additional thalamic components were traced to specific sites within the "posterior group," including a medial component largely traversed by lemniscal axons and a caudolateral component lying between the principal nucleus of the medial geniculate and ventral nucleus of the lateral geniculate.
A topographic organization of projections to the ipsilateral principal nucleus of the inferior olivary complex was demonstrated. Injections involving the oral end of the rostral red nucleus elicited label overlying the medial accessory olive in addition to the principal nucleus.
However, the subparafascicular terminals are more abundant in the rostral and intermediate parts of the medial accessory nucleus and the rubral terminals are concentrated within the dorsal lamella of the principal nucleus.
For example, although dentate fibers end extensively within the principal nucleus some of them also distribute to portions of the medial accessory nucleus and perhaps the dorsal accessory nucleus as well.
In the rat, the highest concentration of catecholamine varicosities was seen within the dorsal lamella of the principal nucleus. The lateral lamella of the principal nucleus contained the highest concentration seen in the rhesus monkey, a finding which contrasts to the minimal number of varicosities seen in this area in the rat and cat.
-
[ View All ]
