（一）微小病变型肾病： LM ：肾小球基本正常 IF ：阴性 EM ：广泛肾小球脏层上皮细胞足突融合 原发性肾病综合征的病理类 型及临床特征
This is a normal glomerulus by light microscopy. The glomerular capillary loops are thin and delicate. Endothelial and mesangial cells are normal in number. The surrounding tubules are normal. Life is good.
（二）系膜增生性肾小球肾炎 ■ LM ：肾小球系膜细胞、系膜基质弥漫增 生 ■ IF ： IgA 或 IgM 、 IgG 、 C 3 于系膜区、系 膜区及毛细血管壁颗粒样沉积 ■ EM ：系膜区，有时内皮下见到电子致 密物
This is Berger's disease, or IgA nephropathy. The IgA is deposited mainly in mesangium, which then increases mesangial cellularity as shown at the arrow. Patients with IgA nephropathy usually present with hematuria.
（二）系膜增生性肾小球肾炎 ■ LM ：肾小球系膜细胞、系膜基质弥漫增生 ■ IF ： IgA 或 IgM 、 IgG 、 C 3 于系膜区、系 膜区及毛细血管壁颗粒样沉积 ■ EM ：系膜区，有时内皮下见到电子致 密物
This immunofluorescence micrograph demonstrates positivity with antibody to IgA. Note that the pattern is that of mesangial staining. This is IgA nephropathy.
（三）系膜毛细血管性肾小球肾 炎 病理： LM ：系膜细胞及基质弥漫增生，毛细 血管袢呈 “ 双轨征 ” IF ： IgG 、 C 3 呈颗粒状系膜区及毛细血 管壁沉积 EM ：系膜区、内皮下电子致密物沉积
This is membranoproliferative glomerulonephritis (MPGN). Those that are idiopathic are divided into types I and II by pathologic findings. As seen here, the glomerulus has increased overall cellularity, mainly mesangial.
This electron micrograph demonstrates a mesangial cell at the lower left that is interposing its cytoplasm at the arrow into the basement membrane, leading to splitting and reduplication of basement membrane that is piled up above the mesangial cytoplasm in this micrograph. This is MPGN type I. These characteristic EM changes occur when the mesangial cell (which has a macrophage-like function) goes after subendothelial immune deposits, but makes a mess of the basement membrane in the process.
This electron micrograph demonstrates the dense deposits in the basement membrane of MPGN type II. There are dark electron dense deposits within the basement membrane that often coalesce to form a ribbon-like mass of deposits.