The monolayer columnlike epithelia constitute the proximal convoluted tubule and its nucleolus that located in the middle part of cell is roundness and there are abundant mitochondria in cytoplast.

• 近曲小管由单层柱状上皮细胞构成，细胞核圆形，位于细胞中部，胞质内含有丰富的线粒体；