The projection field of the stria terminalis in the rat brain. An experimental study

Abstract

The problem of the stria terminalis projection field has been examined by use of two versions of the cupric‐silver technique as well as variations of the Fink‐Heimer and Nauta‐Gygax techniques applied to material fixed under different conditions using brains from very young rats surviving 30 hours to four days after production of lesions at different levels of the course of the stria terminalis and related structures. The findings are as follows: A dorsal subventricular portion of the stria terminalis divides into retrocommissural and supracommissural contingents which together account for degenerating terminals seen in the ipsilateral bed nuclei of the stria terminalis and of the anterior commissure, and in the medial preoptic‐hypothalamic junction area. The supracommissural bundle also disseminates into the laterobasal septum, nucleus accumbens, olfactory tubercle, the posterior and medial divisions of the anterior olfactory nucleus, and the granular layer of the accessory olfactory bulb. Additional fibers end in the paucicellular capsule of the ventromedial hypothalamic nucleus, also in a small lateral parvocellular tuberal nuclear area, and throughout the premammillary nuclei. A small truly commissural division of the dorsal component was traced to the contralateral cortical amygdaloid nucleus and to small clusters of medial amygdaloid cells. A ventral juxtacapsular portion of the stria terminalis was traced to the ipsilateral strial bed nucleus, medial preoptic‐hypothalamic junction area, the entire ventromedial hypothalamic nucleus, the lateral tuberal area and the premammillary nuclei. The lateralmost fibers of the dorsal strial component as well as those of the ventral component which lie lateral to the “commissural bundle” appear to terminate exclusively in the lateral portions of the bed nucleus of the stria. A “commissural bundle” or component, after crossing the midline in the anterior commissure, ends in the bed nucleus of the posterior limb of the latter, in the olfactory tubercle, prepiriform cortex, lateral amygdaloid nucleus and the strial bed nucleus. It is thus a decussation rather than a commissure. No contribution from stria terminalis to stria medullaris could be identified.