ABSTRACT
Annulate lamellae (AL) in oocytes of eel, Anguilla japonica have been observed with electron microscopy. Two types of AL have been found in the cytoplasm of these cells, one of which is the common type, characterized by a stack of parallelly arranged lamellae with annuli (or rings) as shown in figure 1, another is a rare one, which appears as alternative arrangement of parellel lamellae with annuli and membrane-like structures as shown in figures 2～4. The only difference between them is the presence of membrane-like structure in the latter. The origin and function of the membrane-like structure have not been found out yet. It is suggested that this structure might be similar to above-mentioned lamellae in origin and might be a "buffer" in function.