The fine structure of zoospores of Harpochytrium hedinii

Abstract

The fine structure of the Harpochytrium hedinii Wille zoospore is reexamined using serial sections. All of the major organelles are located in the posterior two-thirds of the zoospore; the anterior region contains only a few vacuoles and a network of filaments. The basal body complex is located at the center of the posterior end of the zoospore. The nucleus and "nuclear cap" are located directly anterior to the basal body complex on one side of the zoospore. All of the microbodies, lipid globules, and mitochondria are arranged into a complex associated with the rumposome along the opposite side of the zoospore. A spore-wide system of cisternae, the vesicular system, is continuous throughout the posterior region of the zoospore. The overall arrangement of organelles in the H. hedinii zoospore most closely resembles the internal morphologies of certain chytridialean zoospores. This suggests that Harpochytrium may be more closely related to the chytrids than has been previously assumed.