Intrinsic organization of the paramedian pontine reticular formation of the cat.

Abstract

Listen

Translate article

A morphoquantitative analysis was carried out to clarify the cytoarchitectural organization of the paramedian pontine reticular formation (PPRF) which is considered to be an important site in the control of eye movements. The study was carried out on the cat, using the Golgi staining method. The topographic position and detailed structure of the neurons were demonstrated using morphoquantitative methods. On the basis of their neuronal arborization, fusiform neurons and two types of multipolar cells were identified. Fusiform neurons show dendrites which are given off from the two poles of the small- to medium-sized cell body. The arborization generally runs caudorostrally, ending inside the PPRF. These neurons are ubiquitous. Type 1 multipolar neurons, the most frequent elements of the neuronal population (60%), have a small- to large-sized cell body from which 2 or 3 primary spiny dendrites and the axon emerge. Their dendritic field is oval and generally oriented in the vertical plane. These neurons are scattered everywhere in the PPRF. Type 2 multipolar cells are large neurons endowed with numerous primary spiny dendrites constituting a wide round dendritic field and with a thick axon. They are located almost exclusively at the boundaries of the PPRF and preferentially in the caudal region. The characteristics of the neurons suggest that the fusiform cells may play an interneuronal role, while the multipolar neurons could have both a projective function and an important receptive role for the afferent fibers to the PPRF. The lack of homogeneity found among the multipolar neurons is in agreement with the variety of projective elements shown by functional investigations.(ABSTRACT TRUNCATED AT 250 WORDS)