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. 2020 Jan 22;25:102192. doi: 10.1016/j.nicl.2020.102192

Fig. 2.

Fig 2

Fiber dissection of the acallosal brain. (A) The medial surface of the acallosal brain. We could not discriminate the beak of the corpus callosum (CC). CC had a relatively thickened anterior part, while the posterior part was attenuated (arrows). The splenium was absent. CC = corpus callosum. (B) In the acallosal hemisphere, the thickened anterior corpus callosum was a mass of white matter consisting of variously oriented fibers. Thus, this mass is compatible with the Probst bundle (PB). It pushed down the ependyma and crus of the fornix to the thalamic surface. The ependyma was discontinuous (arrows) along the lamina affixa to which the choroid plexus attached. The PB fibers and fornix made a mass of fibers, which was large enough to bury almost the entire anterior horn of the lateral ventricle (PB/F). CC = corpus callosum, E = ependyma, T = thalamus, F = fornix, AC = anterior commissure, PB = Probst bundle, CG = cingulate gyrus. (C) The subcallosal area was indicated by the stippled lines in the acallosal brain. The area was located between the inferior surface of the corpus callosum (CC) and the superior margin of the caudate nucleus (CN). Although the subcallosal areas in the acallosal brain were rather narrow, they were within the normal variations and did not show a different organization from the control fibers. The thalamic peduncles originated from the thalamus, ran through the caudate nucleus and curved acutely to anterior at the superior boarder of the caudate nucleus. The posterior peduncle bundle flanked medially to the anterior bundle and, thus, a narrow ceiling of the caudate nucleus was made by the peduncular bundles. This ceiling was triangular in a coronal view and measured approximately 3 mm base x 3 mm height. CC = corpus callosum, CN = caudate nucleus, T = thalamus, TP = thalamic peduncles. (D) After exposing the total subcallosal areas, only antrorse TP fibers (arrows) in the anteroposterior direction could be found. And removing the corpus callosum (CC) to expose the area above the subcallosal area, no association fibers could be found. CC = corpus callosum, CN = caudate nucleus, T = thalamus, TP = thalamic peduncles.