纺锤体是真核细胞有丝分裂或减数分裂过程中形成的中间宽两端窄的纺锤状细胞结构，主要由大量纵向排列的微管构成。纺锤体一般产生于早前期（PreProphase），并在分裂末期（Telophase）消失。纺锤体主要组件包括极间丝、着丝点丝、星体丝及区间丝四种微管和附着在微管上的动力分子分子马达以及一系列复杂的超分子结构组成。

动物细胞内的纺锤体两端具有由中心粒构成的“星体”，所以动物细胞的纺锤体也称为“星纺锤体”。高等植物的细胞的纺锤体则不含中心体，称为“无星纺锤体”。而真菌细胞的纺锤体含纺锤极体（Spindle Pole Body），一般被视为中心体的同源细胞结构。

In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell.