Electron microscopic observations of a possible tubulin synthesis-polymerization complex in oocytes of a pond-skater.

Maturing oocytes of Gerris najas display, in ultrathin sections, protein fibrils extending from ribosomes, which are often arranged on ring-like cisternae of rough endoplasmic reticulum. In some cases, the fibrils apparently continue into typical microtubules. The possibility is discussed that the huge amount of microtubules of the egg cell is synthesized and polymerized in the form of specific ribosome-tubulin-filament-microtubule complexes.