A microtubular crystal associated with the Golgi field of Pleurochrysis scherffelii.

In young vegetative cells of the Chrysophycean alga Pleurochrysis scherffelii, a characteristic array of microtubules is associated with the Golgi apparatus. This novel structure is described from frozen-etched preparations. The microtubular crystals flank the Golgi stack at either side at an oblique angle and lie in between the Golgi and the periplastidal ER and a parietal vacuole. The microtubules have an outer diameter of 195-230 Å and are spaced in a hexagonal pattern with center-to-center distances of 300-330 Å. The crystals lie free in the cytoplasm and are not surrounded by a membrane although they frequently associate with membraneous elements of the parietal vacuole or periplastidal ER. The microtubules are interconnected by bridge-like links. Possible functions of these crystals, especially in relation to secretion and protoplast rotation, are discussed.