In the inferior olivary nucleus, labeled cells were located in the subnucleus b of the medial accessory nucleus.. 
Since MAO, by its name (medial accessory nucleus) is already identified as a subdivision of IO, we suggest that the term 'subgroup' is appropriate to specify further subdivisions of this nucleus.
Both retrograde and anterograde studies confirmed that the prearcuate cortex in the concavity of the arcuate sulcus, including the frontal eye field, and, to a lesser extent, suprarcuate rostral dorsal area 6 cortex and the dorsomedial convexity (area 9), project to the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) in the dorsal region of the prerubral field, nucleus of Darkschewitsch (ND), medial accessory nucleus of Bechterew (NB) and dorsomedial parvocellular red nucleus (dmPRN).
The densest 5HT immunostaining is present in subnucleus b of the caudal medial accessory nucleus. Fine beaded fibers arborize throughout the neuropil of all the olivary nuclei except in subnucleus b of the caudal medial accessory nucleus where they also circumscribe neuronal cell bodies. In addition, a distinct population of large beaded fibers are occasionally encountered in the neuropil of the medial accessory nucleus. The majority of the labeled profiles were in juxtaposition to small-diameter dendrites (less than 2 microns) except in the caudal medial accessory nucleus, where they also were found in apposition to olivary cell bodies. Further, boutons containing 5HT primarily interact with the distal dendrites of olivary neurons except in the caudal medial accessory nucleus where cell bodies are in apposition to 5HT varicosities..
Caudally, there are terminal fields over the paramedian reticular formation, the caudal part of the medial accessory nucleus of the inferior olivary complex, the nucleus prepositus hypoglossi, and the nucleus reticularis paragigantocellularis dorsalis caudal and ventromedial to the abducens nuclei.
In the rabbit and cat, maximum CA nerve terminals were detected in the dorsal accessory nucleus, while in the monkey, they were detected in the medial accessory 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.
At caudal medullary levels, the mojority of the labeled axons comprising the predorsal bundle pass ventrally to end quite profusely with the subnucleus b of the medial accessory nucleus of the inferior olivary complex.
This projection originates within the deep layers of the superior colliculus, descends within the contralateral tecto-spinal tract, and terminates within the caudal 1/3 of the medial accessory nucleus.
Evidence for a small projection from the fastigial nucleus to the caudal medial accessory nucleus is also available. 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.
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