ULTRASTRUCTURAL-STUDY OF APYRENE SPERMATOZOA OF ALABAMA-ARGILLACEA (INSECTA, LEPIDOPTERA, NOCTUIDAE) WITH TANNIC-ACID CONTAINING FIXATIVE

The lepidopterans produce two kinds of spermatozoa, the eupyrene and t he apyrene cells. The ultrastructural organization of the apyrene sper matozoa of the noctuid moth Alabama argillacea is described, as reveal ed by use of a special tannic acid-fixative (Afzelius, 1988). At the a nteriormost tip of this kind of sperm, there is only a short electron- dense cap instead of the nucleus. This cap also covers the peripheral tubules that gradually form a centriole-like structure. The proximal e nd of the flagellar membrane is covered by a thin fuzzy coat, probably reminiscent of the dense cap. The tubular pattern of the complete axo neme is 9+9+2, typical of most insect orders. At the middle piece of t he flagellum, the number of wall protofilaments of the central tubules , and of subtubules A and B of the doublers is identical to that of ot her insect spermatozoa. The large peripheral accessory tubules have 16 protofilaments in their walls as usual for many insect species. Their lumina are filled with 8-9 electron lucid subunits in a regular arran gement. The intertubular material between the accessory tubules is dif ferentiated in two regions, a thicker and a thinner one. The two mitoc hondrial derivatives apposed to the axoneme are equal in size and form , and present a usual V disposition; they have a partially crystallize d matrix. At the distal end of the flagellum, the mitochondrial deriva tives may end or not at the same level. In the axoneme, the accessory tubules are the last ones to disorganize, maintaining their substructu re.