On the striate area of the human isocortex. A Golgi- and pigmentarchitectonic study.

The distribution pattern of the pigment in various layers of the primary visual cortex of man is described by means of a method for the stereomicroscopical demonstration of neurolipofuscins in sections up to 1,000 mum thick. This paper presents the striate area as being composed of 12 cellular layers, which can be clearly delineated by a successive examination of both the Nissland the pigment preparations. Layers I, II, and III resemble more or less the corresponding laminae of other isocortical fields. The pyramids within the deep portion of layer III are unusually small and additionally are intermingled with thorny stellate cells which are a characteristic component of layer IV. Accordingly, this band of cells is called IIIc-IVa. The subjacent layers IVb and IVcalpha are poorly pigmented. In Nissl-preparations layer IVb, which contains only a few cells, is followed by a broad band of cells tightly packed together, which includes layers IVcalpha, IVcbeta, IVd, and Va. These layers cannot be reliably delineated in Nissl-preparations but appear in pigment preparations as distinct and sharply limited laminae. Particularly, layer IVcbeta, which is built up by minute thorny stellate cells, is marked by coarse and intensely stained lipofuscin granules, whereas IVd is mainly populated by minute pyramids which are almost devoid of pigment deposits. A remarkably narrowed layer Va, the pyramids of which store a medium number of lipofuscin grains, completes this series (IVcalpha, IVcbeta, IVd, Va). The cell-sparse layer Vb is almost devoid of pigment granules. Layer VIa has specialized pyramidal cells containing finely grained pigment. The relatively broad layer VIb shows loosely arranged cells poorly endowed with lipofuscin granules.