McMullen N T, Smelser C B, de Venecia R K
Department of Anatomy, University of Arizona College of Medicine, Tucson 85724.
J Comp Neurol. 1994 Nov 22;349(4):493-511. doi: 10.1002/cne.903490402.
Parvalbumin (PV) is a calcium-binding protein present in GABAergic cells in the cerebral cortex and in thalamic relay neurons. In the present study, parvalbumin immunocytochemistry (PVi) and stereological methods were used to obtain estimates of cortical volume, total neuron number, laminar density, and the percentage of PV-immunoreactive neurons in auditory neocortex. PVi clearly delineated the primary auditory cortex (AI), which was characterized by two PV+ bands: dense terminal-like labeling within lamina III/IV and PV+ somata in lamina VIa. Stereological analysis of Nissl-stained sections revealed that the total number of neurons in rabbit AI was 1.48 x 10(6) with a mean neuronal density of 55 x 10(3)/mm3. Based on a mean cortical thickness of 1.92 mm, there are approximately 106,000 neurons in a 1 mm2 column of auditory cortex. PVi yields an extraordinary Golgi-like staining of nonpyramidal cells in all cortical layers. PV+ nonpyramidal cells constitute approximately 7.0% of the neurons in AI. There were significant differences in the morphology and density of PV+ neurons across layers. Although only 5% of cells in lamina I were PV+, three nonpyramidal cell types were present. Lamina II had the highest numerical density within AI but the lowest percentage of PV+ neurons (3.3%). Lamina II, however, contained the greatest diversity of PV+ nonpyramidal cell types, which included small multipolar cells, bipolar cells, and, less frequently, large cells of the bitufted, bipolar, and stellate varieties. Lamina IV had one of the highest numerical densities (67.6 x 10(3) neurons/mm3) and contributed nearly 27% of the total neuron number in AI. The numerical density of PV+ nonpyramidal cells was also greatest within lamina IV (7.1 x 10(3)/mm3) where they formed 10.4% of the neuronal population. PV+ nonpyramidal cells in lamina IV and lamina III were predominantly large basket-type cells with bitufted dendritic domains and tangentially oriented local axonal plexuses. The terminal-like label within lamina III/IV derived in part from the basket-cell axons, which formed pericellular arrays around unstained somata. Cell-sparse lamina V contained the largest PV+ nonpyramidal cells in AI. These cells, which formed 11% of the neuron population in lamina V, were notable for their tangentially oriented dendritic fields and local axonal arbors. PVi partitioned lamina VI into VIa and VIb. Large multipolar nonpyramidal cells were distributed throughout lamina VI and made up approximately 6% of the total population. Lamina VIa contained a band of lightly labeled PV+ pyramidal neurons that formed 15% of the neuronal population.(ABSTRACT TRUNCATED AT 400 WORDS)
小白蛋白（PV）是一种存在于大脑皮层GABA能细胞和丘脑中继神经元中的钙结合蛋白。在本研究中，采用小白蛋白免疫细胞化学（PVi）和体视学方法来估计听觉新皮层的皮质体积、神经元总数、层密度以及PV免疫反应性神经元的百分比。PVi清晰地勾勒出初级听觉皮层（AI），其特征为两条PV+带：III/IV层内密集的终末样标记和VIa层中的PV+胞体。对尼氏染色切片的体视学分析显示，兔AI中的神经元总数为1.48×10⁶，平均神经元密度为55×10³/mm³。基于平均皮质厚度1.92mm，听觉皮层1mm²柱内约有106,000个神经元。PVi对所有皮质层中的非锥体细胞产生了类似高尔基染色的非凡染色效果。PV+非锥体细胞约占AI中神经元的7.0%。PV+神经元在各层的形态和密度存在显著差异。虽然I层中只有5%的细胞是PV+，但存在三种非锥体细胞类型。II层在AI中具有最高的数字密度，但PV+神经元的百分比最低（3.3%）。然而，II层包含了最丰富多样的PV+非锥体细胞类型，包括小多极细胞、双极细胞，以及较少见的双簇、双极和星状的大细胞。IV层具有最高的数字密度之一（67.6×10³个神经元/mm³），占AI中神经元总数的近27%。IV层中PV+非锥体细胞的数字密度也最大（7.1×10³/mm³），它们占神经元群体的10.4%。IV层和III层中的PV+非锥体细胞主要是大篮状细胞，具有双簇树突域和切向排列的局部轴突丛。III/IV层内的终末样标记部分来自篮状细胞轴突，这些轴突在未染色的胞体周围形成细胞周阵列。细胞稀疏的V层包含AI中最大的PV+非锥体细胞。这些细胞占V层神经元群体的11%，以其切向排列的树突场和局部轴突分支而显著。PVi将VI层分为VIa和VIb。大型多极非锥体细胞分布在整个VI层，约占总人口的6%。VIa层包含一条轻度标记的PV+锥体神经元带，占神经元群体的15%。（摘要截断于400字）
