) and at the inferior margin of the hemisphere the third occipital sulcus. The latter might already be referred to as the third temporal sulcus here (s.o.III). selleck compound The collateral fissure (coll.) is again visible adjacent to the inferior part of the stratum sagittale externum. On the medial aspect the fissure calcarina (f.c.) and the occipito-parietalis sulcus (o.) are abutting just after they have merged. The cross-section of the precuneus shows the posterior elongation of the calloso-marginal sulcus (cm.). The occipital horn in this particular specimen is rather wide in its anterior half. In comparison to the previous section, it gained in width and formed a prominent dorsal surface, which is protruding

convex into the ventricle dorsally due to the protrusion of the dorsal part of the forceps. The dorsal part of the forceps (1.) gained significantly in size and continues at the lateral surface of the occipital horn (2.) into the vertically ascending fibres. These fibres appear as longitudinally cut under the microscope (compare figure 3 and 9). The forceps fibres underneath the occipital horn are cut longitudinally where they reach for the stratum sagittale internum and are cut transverse where they are close to the ventricle (Fig 3.7.). The inferior part of the forceps (4.) is still located at the inferior margin of the occipital selleck horn. The connection

between this and the dorsal part is formed by a thin layer of fibres that are cut transversely and that run along the inner surface of the occipital horn, namely the medial forceps layer (3.). The stratum sagittale internum (5.) disappeared where the calvar avis is penetrating the white matter and is not visible in this specimen under the microscope. The part of it that is located lateral to the occipital horn is formed by transversely cut fibres, whilst its fibres dorsal and inferior to the forceps are cut longitudinally and constitute the addition to this layer that comes from the cortex of the medial occipital lobe. The beak-like extension of the stratum into the gyrus lingualis, which was already present on the previous section, can still Isotretinoin be visualised here.

The beak appears as a transversally cut fibre bundle under the microscope. The stratum sagittale externum (6.) is similar to the internum in its shape. Its inferior part is further thinned and bend due to the collateral sulcus. On the lateral aspect it is already visible to the naked eye that the layer is disappearing due to the various penetrations of thin bundles of fibres designated to reach the forceps. In the inferior part the fibres are transversely cut whilst in the dorsal part they are cut aslant. When comparing this section to the previous one, the formation of bundles from forceps fibres is evident in the region between the stratum sagittale internum and the externum. The strata priopria of the interparietal sulcus (10.) and the collateral sulcus (12.) are clearly distinct from deep layers of the cortex (9.