A study of the oocytes of the earthworm, Pheretima posthuma, examined fresh under the phase-contrast and interference microscopes as well as by histochemical techniques, has revealed that there are two types of lipid bodies in the cytoplasm. The lipid bodies of the first type (L1) are smaller, appear as homogeneous, dark granules under the phase-contrast microscope, and have a protein-phospholipid core surrounded by a thick sheath of phospholipids only. The lipid bodies of the second category (L2), which arise as a result of growth and chemical change in L1 bodies, have a pure phospholipid core surrounded by a thick triglyceride sheath. They give a ringed appearance under the phase-contrast microscope. The study under the interference microscope shows that this ringed appearance is an optical artifact. The lipid spheres present in the follicular epithelium contain phospholipids only.
The mitochondria are in the form of minute granules. They remain unchanged throughout oogenesis.
Some vacuoles devoid of any lipids, proteins, or carbohydrates have been observed. They also remain unchanged.
Pure triglyceride spheres, yolk globules, nucleolar extrusions, as well as cholesterols and cholesteryl esters are absent.
