The cells of origin of the incertofugal projections to the tectum, thalamus, tegmentum and spinal cord in the rat: A study using the autoradiographic and horseradish peroxidase methods

Abstract

Efferent projections of the zona incerta were examined in the rat using the autoradiographic and horseradish peroxidase methods, with special reference to the cytoarchitectonic structure of the zona incerta. Autoradiographic experiments showed that the incertofugal fiber systems reach ipsilaterally to the thalamus (lateral dorsal, central lateral, ventral lateral geniculate, parafascicular, subparafascicular and reuniens nuclei, and posterior nuclear complex), to the hypothalamus (dorsal, lateral and posterior hypothalamic areas), to the tectum (medial pretectal area, deep pretectal and pretectal nuclei, superior colliculus and periaqueductal gray) and to the midbrain tegmentum, pons and medulla oblongata (subcuneiform, cuneiform and red nuclei, nuclei of the posterior commissure and Darkschewitsch, interstitial nucleus of Cajal, pedunculopontine tegmental nucleus, oral and caudal pontine reticular nuclei, nucleus raphe magnus, gigantocellular reticular nucleus, pontine gray and inferior olivary complex). Contralaterally, incertal efferent fibers reach to the zona incerta. Cells of origin of the incertofugal fiber systems to the tectum, thalamus, tegmentum and spinal cord were examined using the retrograde horseradish peroxidase method. Cells of origin of the incertotectal pathway are located mainly in the ventral and causal parts of the zona incerta and partly in the antero-polar, dorsal and postero-polar parts. Cells projecting to the thalamus (at least to the lateral dorsal and central lateral nuclei) are situated in the ventral and caudal parts of the zona incerta, but they are rare in the other incertal structures. Cells of origin of the incertotegmental system are located mainly in the dorsal, magnocellular and caudal parts and partly in the antero- and postero-polar parts, but they are not situated in the ventral part. Cells of the magnocellular part project more caudally to the medulla oblongata and spinal cord than those of the other parts of the zona incerta. Forel's field contains many cells projecting to the tegmentum. The results provide good evidence that the cells of origin of efferent projections are topographically organized and are related to cytoarchitectonic areas within the zona incerta.

"Calciosome," a cytoplasmic organelle: the inositol 1,4,5-trisphosphate-sensitive Ca2+ store of nonmuscle cells?

“…Countings over pictures chosen at random (28 and 49 cellular profiles for HL-60 and PC12) showed the average concentration (number per unit area) in the cytoplasm to be 0.1 and 0.08 per ILm2 , respectively. Assuming each CS-positive structure to be a discrete organelle (see Discussion), the total number in a PC12 cell [for which a morphometric study is available (23)] can be calculated to be around 5000. In rat hepatocytes (Fig.…”

Glucose Utilization During Interictal Intervals in an Epilepsy Model Induced by Pilocarpine: A Qualitative Study

“…The pretectal area is interconnected with superior colliculus and zona incerta (19). These structures receive projections from the cortex and have widespread projections that may influence seizure activity.…”

Projections of somatosensory cortex and frontal eye fields onto incertotectal neurons in the cat

“…11). Cells in vZI are known to project to the SC, nucleus of Darkschewitsch, and the thalamic posterior and lateral posterior nuclei [cat: May et al (1997) and Onodera and Hicks (1998); rat: Watanabe and Kawana (1982), Roger and Cadusseau (1985), Romanowski et al (1985), and Power and Mitofanis (1999a)]. The projections of dZI have mainly been described in the rat.…”

“…The projections of dZI have mainly been described in the rat. They include projections to the parafascicular nucleus and the pontomedullary tegmentum (Watanabe and Kawana, 1982;Romanowski et al, 1985;Power and Mitofanis, 1999b). The dZI is also the source of a GABAergic projection to layer I of cerebral cortex (Lin et al, 1990;Nicholelis et al, 1992).…”

“…rat: Watanabe and Kawana (1982), Lin et al (1997), and Power and Mitrofanis (1999a)]. In contrast, the cells of origin for the incertotectal projection are primarily found in the vZI [cat: Ficalora and Mize (1989); May et al (1997); monkey: May (2006); rat: Wantanabe and Kawana (1982), Romanowski et al (1985)].…”