Branching projection of the nucleus "k" neurons to the rabbit cerebellar paramedian lobule: a retrograde fluorescent tracing study.
The nucleus "k", in the reticular core of the rabbit caudal pons, is divided into a large medial (composed of dorsal k1 and ventral k2) and a small lateral (k3) subdivision. In this study, the nucleus "k" subdivisions were examined in the rabbit with respect to projections to the cortex of rostral (rPML; face-forelimb region) and caudal (cPML; hindlimb region) paramedian lobule of the cerebellum. The retrograde fluorescent labeling method with Fast Blue (FB) and Diamidino Yellow (DY) was used. Numerous single FB or DY labeled neurons were found in defined regions of all nucleus "k" subdivisions bilaterally, with an ipsilateral preponderance. The distribution of these neurons indicated that afferents originating from different nucleus "k" subdivisions terminated in overlapping regions within the rPML and the cPML rather than in separate domains. Apart from this, double FB + DY labeled neurons (n = 104) were intermingled within a common region of single labeling, but exclusively on the ipsilateral side. Such neurons occupied predominantly the central and lateral regions of the caudal two thirds of the k1 subdivision, and were scattered in the caudal half of k2 as well as throughout the entire rostrocaudal extent of the k3 subdivision. The size of labeled perikarya varied from 20 to 40 microm in diameter. The number of neurons with branching axons was considerably lower than those with single projections to the rPML and the cPML. It amounted to about 3% in k1 and k3, and 2% in the k2 subdivision. However, this population may form an intralobular link between two somatotopically non-corresponding PML regions. The present study provides a morphological basis for further investigations for comparison with other species using both anatomical and electrophysiological methods, also with respect to other connections of the nucleus "k".
Department of Neurobiology, University School of Physical Education, 55 Grunwaldzka St., 60-352 Poznań, Poland. bukowska@awf.poznan.pl
Dorota
D
Bukowska
Leszek
L
Zguczyński
Jan
J
Celichowski
D000818:Animals; D001370:Axonal Transport; D002529:Cerebellar Nuclei / Q000033:anatomy & histology*; D005260:Female; D005456:Fluorescent Dyes; D008297:Male; D009474:Neurons / Q000166:cytology*; D011817:Rabbits / Q000033:anatomy & histology*
D005456:Fluorescent Dyes