Supraoptic Commissure

In both postnatal and adult brains, ERRbeta immunoreactive fibers were distributed in a pattern which perfectly matched the retinal efferent projections: optic tract, supraoptic commissure, hypothalamic suprachiasmatic nucleus, ventral and dorsal geniculate nuclei, pretectal nuclei, and superior colliculus.  

After BDA injections into nucleus rotundus, retrogradely labelled neurons were observed consistently within the following neuronal groups in the midbrain and the diencephalon: (i) the stratum griseum centrale of the optic tectum; (ii) the nucleus subpretectalis in the pretectum; (iii) the nucleus ansa lenticularis posterior, the posterior nucleus of the ventral supraoptic commissure, and the posteroventral nucleus, in the dorsal thalamus and (iv) the lateral suprachiasmatic nucleus and part of the reticular complex in the ventral thalamus.  

Fibers cross the midline in the supraoptic commissure by E12, other arrive in the lateral geniculate region, and a branch of the MFB extends toward the mammillary area.  

A high concentration of tenascin was found in areas bordering the developing visual pathway, such as the optic disc, the outer surface of the optic nerve, and the supraoptic commissure.  

An additional case proved that this projection courses through the ventral supraoptic commissure.  

At the earliest stages no axon bundles are recognizable in the stalk, but fibers of the supraoptic commissure are already beginning to cross the midline in the diencephalon.  

Birds submitted to visual Wulst ablation or supraoptic commissure lesion performed in much the same way.  

Four days after treatment, the numbers of CA terminals and axons were significantly reduced in the paraventricular hypothalamic nucleus, periventricular hypothalamic nucleus, supraoptic commissure (SOC), and dorsomedial hypothalamic nucleus as assessed by a morphometric quantitation on fluorescence microscopy micrographs; CA axons were gradually increased in numbers after the treatment. The number of CA varicosities in the supraoptic commissure was restored to 96% of control 180 days after the 6-OH-DA lesion, whereas the actual numbers of CA varicosities in the paraventricular, periventricular, and dorsomedial hypothalamic nuclei were attained at 79, 79, and 68% of control values, respectively. Our results indicate that CA fibers in the supraoptic commissure possess more regenerative potential than the three other hypothalamic regions studied, suggesting a regional difference in CA nerve sprouting during neuroplasticity within the hypothalamus. The favorable regeneration of CA axons in the supraoptic commissure implies to us that some trophic features along that pathway, particularly near the third ventricle, may have been stimulated after chemical lesion using 6-OH-DA, and gradually released in the distal field of the supraoptic commissure to attract CA stumps to sprout. These factors may thus induce both regenerative sprouting and collateral sprouting resulting in vigorous regrowth of CA fibers in the supraoptic commissure..  

Experiments were done in urethane anesthetized rats to identify single units in the region of the parabrachial nucleus (PBN) projecting directly to 'cardiovascular' responsive sites in either the paraventricular nucleus of the hypothalamus (PVH) or the supraoptic commissure and nucleus (SOC-SON) region.  

Crossed fibers of the nucleus tegmenti pedunculopontinus pars compacta were observed sparsely at the levels of the thalamus and posterior commissure, and to a greater degree through the supraoptic commissure of Meynert.  

Evidence was obtained suggesting that the short-latency component is generated by activity that reaches the VMN directly through the ventral supraoptic commissure, while the long-latency response involves substations in the amygdala and the bed nucleus of the stria terminalis.  

As in studies from other laboratories, we observed many LHRH cells in the periventricular medial preoptic area, diagonal band of Broca and septal nuclei, and fewer positive cells in the anterior hypothalamic area and the region of the supraoptic commissure.  

The principal ascending bundle projects to the nucleus rotundus, three components of the ventral geniculate nucleus and the nucleus ventromedialis anterior ipsilaterally, before it crosses in the supraoptic commissure and terminates in the contralateral nucleus rotundus, ventral geniculate nucleus and a hitherto unnamed region dorsal to the nucleus of the posterior accessory optic tract.  

The question of age as a possible factor influencing the regenerative response of catecholaminergic varicosities in the hypothalamus was investigated in the supraoptic commissure and the paraventricular, periventricular, and dorsomedial hypothalamic nuclei of rats that had received intraventricular injections of the neurotoxin 6-hydroxydopamine when they were (1) neonates, (2) young adults, or (3) senescent adults.  

HRP injections into the pretectal area, lateral geniculate body, suprachiasmatic nucleus and lateral hypothalamic area resulted in the labeling of neurons in the middle subgroup only when the supraoptic commissure and optic tract were injured by a pipette used in injections. Electrolytic lesions of the supraoptic commissure combined with collicular HRP injections resulted in no labeling of cells of the middle subgroup. From these findings, it could be concluded that neurons of the dorsal and ventral subgroups sent axons to the ipsilateral superior colliculus, and that fibers of neurons of the middle subgroup coursed through the supraoptic commissure to the contralateral superior colliculus..  

Similarly, the retrochiasmatic area sends its efferents through the ventral supraoptic commissure to the amygdala, the anterior periventricular nucleus contributes to the periventricular fiber system and to the external lamina of the median eminence, and the accessory supraoptic neurons project to the internal lamina of the median eminence..  

The third commissural projection arises more rostrally and crosses in the dorsal supraoptic commissure to enter the contralateral medial forebrain bundle.  

Some labeled axons continue through the bed nucleus of the stria terminalis into the stria itself, and hence to the amygdala, where they join other fibers which follow a ventral amygdalopetal route from the lateral hypothalamic area and ventral supraoptic commissure. A lesser number of rostrally directed fibers from the VMH crosses the midline in the ventral supraoptic commissure and contributes a sparse projection to the contralateral amygdala. Descending fibers from the VMH take three routes: (i) through the medial hypothalamus and medial forebrain bundle; (ii) through the periventricular region; and (iii) bilaterally through the ventral supraoptic commissure. The ventral supraoptic commissure fibers leave the hypothalamus closely applied to the medial edges of the two optic tracts.  

Other AHA efferents distributed to the periventricular thalamus, to the medial amygdala via the stria terminalis or supraoptic commissure, and to the lateral habenula through the stria medullaris.  

Decussating fibers in both the ascending and descending pathways cross in the ventral supraoptic commissure.  

Throughout the ascending course of the path from the locus coeruleus, axons were given off to the pretectal area, the medial and lateral geniculate nuclei and the amygdala; fibers passed contralaterally through the posterior commissure, the midline thalamus, and the supraoptic commissure.  

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