PALLIDOFUGAL FIBERS IN THE MONKEY

Abstract

In a series of rhesus monkeys (Macaca mulatta) lesions were placed in the lateral part of the hypothalamus. Subsequent microscopic examination showed that the pallidofugal fibers of the ansa and fasciculus lenticularis had been interrupted and that the cells of the medial division of the globus pallidus had disappeared. Observations made on this material and on the brains of normal monkeys are briefly reported here. MATERIAL AND METHODS The operative procedures and the location of the lesions have been described elsewhere (Ranson1). The 11 animals used in this study were allowed to live for periods ranging from twenty-nine to seventy-eight days. The basal ganglia and mesencephalon were fixed in formaldehyde, embedded in pyroxylin, cut serially and alternate sections stained by the Weil method for fibers and with cresyl violet for cells. The extent and location of the lesions and the retrograde degeneration seen in the pallidofugal fibers have been