The phylum Apicomplexa has been defined by the presence of the apical complex, a structure composed of secretory organelles and specific cytoskeletal elements. A conspicuous feature of the apical complex in many apicomplexans is the conoid, a hollow tapered barrel structure composed of tubulin fibers. In Toxoplasma gondii, the apical complex is a central site of convergence for calcium-related and lipid-mediated signaling pathways that coordinate conoid protrusion, microneme secretion, and actin polymerization, to initiate gliding motility. Through cutting-edge technologies, great progress has recently been made in discovering the structural subcomponents and proteins implicated in the biogenesis and stability of the apical complex and, in turn, these discoveries have shed new light on the function and evolution of this definitive structure.

顶叶复合体是由根尖复合体的存在定义的，该复合体由分泌性细胞器和特定的细胞骨架成分组成。圆锥形复合体在许多蜂复合体中的显着特征是圆锥形，由微管蛋白纤维组成的空心锥形桶状结构。在弓形虫中，根尖复合体是钙相关的和脂质介导的信号传导途径汇聚的中心部位，这些信号传导通路协调类固醇突突，微neme分泌和肌动蛋白聚合，从而启动滑行运动。通过尖端技术，最近在发现与根尖复合体的生物发生和稳定性有关的结构亚成分和蛋白质方面取得了重大进展，这些发现又为这种最终结构的功能和进化提供了新的思路。