Search

The spermatozoa of Bephratelloides pomorum are very long and fine. Each spermatozoon measures about 620 μm in length by 0.38 μm in diameter and, when seen under the light microscope, appears to be wavy along its entire length. The head, which is approximately 105 μm, comprises a small acrosome and a nucleus. The acrosome is made up of a cone-shaped acrosomal vesicle surrounding the perforatorium and the anterior end of the nucleus. Innumerable filaments radiate from it. The perforatorium has a diameter equal to that of the nucleus at their junction, where it fits with a concave base onto the rounded nuclear tip. The nucleus is helicoidal and completely filled with homogeneous compact chromatin. It is attached to the tail by a very long and quite electron-dense centriolar adjunct that extends anteriorly from the centriole in a spiral around the nucleus for approximately 8.5 μm. The tail consists of an axoneme with the 9+9+2 microtubule arrangement pitched in a long helix, as well as a pair of spiraling mitochondrial derivatives (with regularly arranged cristae) that coil around the axoneme, and two small accessory bodies. As well as the spiraling of the nucleus, mitochondrial derivatives and axonemal microtubules, the sperm of B. pomorum present other very different morphological features. These features include the acrosome and centriolar adjunct, both of which differentiate the spermatozoa from the majority of sperm found in other Hymenoptera. In addition these structural variations demonstrate that the sperm of chalcidoids provide characteristics that can certainly prove useful for future phylogenetic analysis at the subfamily level and, possibly, the genus too.

The ultrastructure of the mature sperm of the mayfly, Dolania americana Edmunds and Traver (Ephemeroptera : Behningiidae), is described from scanning and transmission electron microscopy. The head is 0.7–1 μm wide and 4.6–6.9 μm long, rodlike, and topped by a short, rounded acrosome 0.4 μm long and 0.6 μm wide. The flagellum is 5–6 times the head length and is flattened, except for a thin, tubelike terminal portion. The axoneme pattern is 9-9-1 (9 outer singlet microtubules, 9 doublet microtubules, and a central dark element) and is new for Ephemeroptera. The inner dynein arms are conspicuous and outer arms are lacking, and radial spokes and a central sheath are prominent. A densely-staining and bi-lobed accessory body lies adjacent to the axoneme. A mitochondrial derivative with regularly arranged transverse-to-oblique cristae lies adjacent to the accessory body.

Spermiogenesis of Anthonomus grandis Boheman, the cotton boll weevil, was studied by transmission electron microscopy. The basic morphologic features investigated and illustrated were: acrosome, nucleus, fibrous masses, microtubules, and mitochondrial derivatives. A centriole adjunct was observed to surround the basal body (centriole derivative) early in spermiogenesis, but it subsequently disappeared. In the sperm tail, one mitochondrial derivative developed into a rod-like structure that inserted into a concavity at the base of the nucleus and terminated near the end of the tail. This mitochondrial derivative may provide a rigid base for the undulating membrane. In addition, the attachment of the rod to the nucleus may serve in a manner analogous to the function that has been suggested for the centriole adjunct: it may anchor the head to the tail. A possible abnormal condition may arise when the mitochondrial derivative rod fails to insert into the sperm nucleus.

To provide a basis for subsequent studies of the effect of X-rays on Dermestes frischii (Coleoptera : Dermestidae), the ultrastructure of the somatic and germ cells of the testes of this species is described. The somatic cells are of 3 types, the apical, cyst wall, and follicle wall cells. The follicle wall consists of a single continuous layer of epithelial cells lying on a basal lamina, which in the germarium is subdivided and contains a discontinuous cell layer. With the exception of the dividing cells, details are given of all the germ cell stages. The pattern of spermatogenesis is generally typical of that observed in other Insecta but several novel observations are reported. In particular, large arc-shaped tubules associated with the nucleus and acrosome in the developing spermatid are reported for the first time and an unusual arrangement in which the axoneme is connected by amorphous strands to the mitochondrial derivatives and plasmalemma is described. The acrosome is very distinctive; the inner cone possesses a ball that fits into a corresponding socket in the nucleus. Details are given of centriole duplication in the primary spermatocyte and the stages leading to the formation of the definitive sperm plasmalemma. Where possible comparisons are made with other Coleoptera.