The nucleus corporis pontobulbaris of the North American opossum

Abstract

The nucleus of the pontobulbar body (PBu) in the North American opossum is located, for the most part, adjacent to the motor root of the trigeminal nerve. Material prepared by degeneration and autoradiographic methods shows that the PBu receives projections from the facial motor-sensory cortex, red nucleus, spinal cord and cerebellum. The latter fibers probably take origin within the fastigial nucleus. Each of the afferent connections ends in a restricuted part of the PBu, but there is considerable overlap. Use of the horseradish peroxidase technique reveals that the PBu projects to the spinal cerebellum (anterior lobe, pyramis and paramedian lobules), to visual-auditory areas of the vermis and to the lobus simplex as well as to crus I and II of the hemispheres. Although there is some topography to such projections, it is not sharply defined and many regions of the PBu contain labelled neurons after injections of horseradish peroxidase into widely separate areas of the cerebellar cortex. Because of its embryogenesis and position, the PBu is often considered part of the dorsolateral basilar pons. It appears from our material, however, that the organization of PBu afferent and efferent connections is different from that of the adjacent basilar pons, and arguments for considering the PBu a separate precerebellar nucleus are presented.

Inputs from identified jaw‐muscle spindle afferents to trigeminothalamic neurons in the rat: A double‐labeling study using retrograde HRP and intracellular biotinamide

“…Although the location of these neurons is near the nucleus of the pontobulbar body (PBu) described in the opossum by Martin and coworkers (19771, its precise location and connectivity are different. Rostrally, the nucleus of the pontobulbar body is located on the ventral surface of the lateral pons between the motor root and spinal tract of the (Martin et al, 1977). In contrast to PBu, the region we have designated as AVM is located immediately ventral to Vmo and medial to Vp.…”

“…More caudally, PBu occurs ventral to the ventral pole of Vp just medial to the exiting fascicles of the trigeminal motor root. The nucleus of the pontobulbar body receives input from the cerebral cortex, red nucleus, spinal cord, and cerebellum and projects to the cerebellum (Martin et al, 1977). In contrast to PBu, the region we have designated as AVM is located immediately ventral to Vmo and medial to Vp.…”

Topographical and cellular distribution of perineuronal nets in the human cochlear nucleus

“…In stark contrast to what we will describe below for the VCN, we never observed perineuronal nets within the PBB. In summary, the arrangement of neurons along the pontomedullary junction associated with the vestibulocochlear nerve is complex and includes many neurons associated with functions beyond hearing or vestibular function (Martin et al, 1977;Terr and Sinha, 1987).…”