Annulate Lamellae: Structure And Functions Review

Annulate lamellae (AL) are found in the cytoplasm and consist of stacks of flattened membrane cisternae perforated by numerous and densely packed pore complexes lacking both chromatin and a lamina. AL are frequently observed in rapidly growing or differentiating cells, such as male and female gametes, tumor ceils, and virally infected cells. Nuclear and annulate lamellae pores appear morphologically indistinguishable in their basic structure when viewed by a number of different electron microscopy techniques. Since AL are relatively easier to observe in germ cells, most of our knowledge concerning this organelle and speculations as to the proposed function of these cytomembranes has arisen from morphological studies of annulate lamellae during the course of germ cell maturations. Most cells have an inherent propensity towards AL formation . Even though annulate lamellae are not a ubiquitous feature of terminally differentiated cells, it is possible to induce the formation of the AL network in cells. The purpose of this review is to acquaint or reacquaint the reader with this inracellular membrane network and to adres a number of basic questions concerning the orgin, function, and fate this rather intriguing cellular organelle.