Sperm Bundles in the Seminal Vesicle of the Crematogaster victima (Smith) Adult Males (Hymenoptera: Formicidae).

This study establishes the presence of spermatodesm in the seminal vesicles of sexually mature males of Crematogaster victima (Smith). In this species, the spermatozoa are maintained together by an extracellular matrix in which the acrosomal regions are embedded. This characteristic has not yet been observed in any other Aculeata. However, the sperm morphology in this species is similar to that described for other ants. The spermatozoa measure on average 100 µm in length, and the number of sperm per bundle is up to 256. They are composed of a head formed by the acrosome and nucleus; this is followed by the flagellum, which is formed by the centriolar adjunct, an axoneme with a 9 + 9 + 2 microtubule pattern, two mitochondrial derivatives, and two accessory bodies. The acrosome is formed by the acrosomal vesicle and perforatorium. The nucleus is filled with compact chromatin with many areas of thick and non-compacted filaments. Both mitochondrial derivatives have the same shape and diameters. The presence of sperm bundles in sexually mature males differentiates C. victima from other ants; however, the similarities in the sperm ultrastructure support the monophyly of this insect group.

Sperm morphology of the Prorops nasuta (Waterston, 1923) (Hymenoptera: Bethylidae).

In the present study, spermatozoa of the Prorops nasuta (Hymenoptera: Bethylidae) parasitoid were described morphologically. This is the first publication to describe a species belonging to the superfamily Chrysidoidea. Light and transmission electron microscopy were used. The spermatozoa of P. nasuta are linear, with a mean length of 665microm. The acrosome is composed of an acrosomal vesicle and a perforatorium. The nucleus measures approximately 17microm in length and is circular at its cross-section; however, its anterior extremity is oval. The chromatin is electron-dense and compact, although there are clear areas in the posterior peripheral regions. In the nucleus-flagellum transition region, the cross-section of the centriole adjunct is oval, with a pleated border and an E-PTA-positive peripheral region. The axoneme shows a 9+9+2 microtubule arrangement. The microtubules are E-PTA positive and, at the posterior extremity, the accessories are the last to terminate. The diameters and shapes of the two mitochondrial derivatives are almost identical. One begins beside the nuclear base and the other after the centriole adjunct. Posteriorly, they terminate together, immediately before the axoneme. Both have mitochondrial cristae and a region of paracrystalline material; however, the format and arrangement of this material differs from those of all other species previously studied. The paracrystalline material is more strongly E-PTA positive than the cristae region. Accessories bodies are electron-dense and located between the mitochondrial derivatives and the axoneme. In general, P. nasuta spermatozoa are similar to those of the majority of Hymenoptera; however, they have various exclusive characteristics that may be useful for studying the phylogeny and taxonomy of the superfamily Chrysidoidea and of Hymenoptera in general.

Morphology of the male reproductive system and spermiogenesis in Hypanthidium foveolatum (Alfken, 1930) (Hymenoptera: Apidae: Megachilinae).

The morphological aspects of male reproductive tract, spermiogenesis and spermatozoa are typical for each species and reflect its evolution, establishing a unique source of characters, which has been used to help solve phylogenetic problems. In Hypanthidium foveolatum the reproductive tract is composed of the testes comprising 28 testicular tubules, deferent ducts, seminal vesicles, accessory glands and an ejaculatory duct. The differentiation of spermatids occurs within cysts of up to 128 germ line cells each one. During the early spermatid phase, the nucleus resembles that of somatic cells. There follows a gradual chromatin condensation with an increase in nuclear electron density. In the spermatozoon, the nucleus contains heterogeneous chromatin with a loose appearance. The acrosome, shaped with the active participation of the Golgi complex, shows an electron-dense perforatorium involved by four electron-lucent acrosomal vesicle projections. The sperm tail presents an axoneme with a 9+9+2 microtubule pattern and two mitochondrial derivatives, which appear with different sizes. A dense crystalloid is formed initially in the mitochondrial matrix of the large derivative. The mitochondrial derivatives' differentiation occurs concomitantly with an axoneme outgrowth. The centriolar adjunct is observed near the axoneme, anterior to the smaller mithocondrial derivative and exhibits an approximately triangular shape in cross-sections. Microtubules were observed around the head region and flagellar components during spermiogenesis.

Structural and ultrastructural characterization of male reproductive tracts and spermatozoa in fig wasps of the genus Pegoscapus (Hymenoptera, Chalcidoidea).

The three Pegoscapus species present the same internal reproductive tract features comprising testes with a single testicular tubule, seminal vesicles, vasa deferentia, accessory glands and an ejaculatory duct. The seminal vesicle shows two morphologically distinct portions although they do not resemble the separate chambers found in other Chalcidoidea. The anterior portion of the seminal vesicle shows a prominent epithelium and stores the mature spermatozoa, while the posterior region is formed by a thicker muscular sheath that participates on ejaculation. The sexual maturation in Pegoscapus is achieved at emergence, when the testicular degeneration occurs. The spermatozoa of Pegoscapus reveal a basic structure similar to that of other Chalcidoidea. In Pegoscapus sp1. and Pegoscapus sp2. they present the same features, whereas Pegoscapus tonduzi comprises some different characteristics. It measures approximately 160 microm in Pegoscapus sp1. and Pegoscapus sp2., while in P. tonduzi the spermatozoa measure about 360 microm. The extracellular sheath thickness is another difference among the species. While Pegoscapus sp1. and Pegoscapus sp2. show a thick extracellular sheath, in P. tonduzi this sheath is very thin resulting in a large space intervening between the extracellular sheath and the nucleus. Despite these differences, the three species analyzed share some characteristics that allow the establishment of an identity to the spermatozoon of the genus Pegoscapus: the seminal vesicle not divided in chambers; the absence of acrosomal structures in the spermatozoa; the length of the extracellular sheath; the central microtubules being the firsts to terminate in the sequence of microtubular cutoff at the final axonemal portion.

Structure and ultrastructure of the spermatozoa of Halictidae (Hymenoptera, Apoidea).

The spermatozoa in Halictidae are sometimes observed in spermatodesmata in the seminal vesicle. They are linear, long, slender and their lengths vary from 213 microm to about 330 pm. The head region consists in the anterior acrosomal complex, formed by a conical acrosomal vesicle that shows an inner paracrystalline perforatorium extending into the nucleus. The nucleus, measuring about 16 microm to 46 microm, is linear and strongly electron-dense, however some electron-lucent lacunae with electron-dense granules homogeneously organized were observed. The nucleus is attached to the flagellum by the centriolar adjunct, which is compact and electron-dense. It begins at the nuclear base and finishes just above the smaller mitochondrial derivative. The flagellum consists of two mitochondrial derivatives, an axoneme and two accessory bodies. Halictidae have an axoneme with 9+9+2 microtubule pattern which gradually disorganizes towards the final region. The mitochondrial derivatives are asymmetric in both length and diameter and only the larger presents the paracrystalline region. The typical pattern for Halictidae spermatozoa here described may provide useful additional information for future phylogenetic analysis of the superfamily Apoidea.

Sperm morphology of mud dauber Sceliphron fistularium dahlbom (Hymenoptera: Apoidea: Sphecidae), as an indication of bees relation.

The morphology of spermatozoon of Sceliphron fistularium is very similar to that described for bees. In particular, the response to E-PTA stains is similar to that observed in corbiculated Apidae, especially Meliponini bees. Spermatozoa measure 285 microm and are composed of 1) a bilayered acrosome (acrosomal vesicle and perforatorium); 2) a homogeneous and compact nucleus; 3) a 9+9+2 axoneme; 4) a rod-shaped centriolar adjunct; 5) two asymmetrical mitochondrial derivatives with paracrystalline material exclusively in the larger one, and 6) two accessory bodies. Only the accessory microtubules of axoneme and the paracrystalline material are E-PTA positive. Comparison of S. fistularium sperm to data on Hymenoptera corroborates their proximity with bees.

Sperm ultrastructure of the bees Exomalopsis (Exomalopsis) auropilosa Spinola 1853 and Paratetrapedia (Lophopedia) sp. Michener & Moure 1957 (Hymenoptera, Apidae, Apinae).

The spermatozoa of Exomalopsis auropilosa and Paratetrapedia (Lophopedia) sp. are long and slender, measuring about 374 microm and 370 microm in length of which the head region measures approximately 25.8 and 28.3 microm, respectively. The head consists of an acrosome formed by an acrosomal vesicle covering a perforatorium, which presents a paracrystalline organization in Paratetrapedia (Lophopedia) sp. and a nucleus. This latter measures about 24 microm in Exomalopsis auropilosa and 27 microm in Paratetrapedia (Lophopedia) sp., and has compact chromatin. The nucleus is attached to the flagellum by an electron dense material and centriolar adjunct is observed between it and smaller mitochondrial derivative. In this flagellar region only one accessory body is observed, which occurs between the larger mitochondrial derivative and the axoneme. The flagellum consists in a typical axoneme, 9+9+2 microtubules, two mitochondrial derivatives and two accessory bodies. The two mitochondrial derivatives are asymmetric in both length and diameter, and paracrystalline material appears only in the larger mitochondrial derivative. The structure and ultrastructure of the spermatozoa of the bee species here described are similar to the majority of sperm found in the other Hymenoptera and may be a contribution for future phylogenetic analysis of Apidae.

Sperm ultrastructure of the honey bee (Apis mellifera) (L) (Hymenoptera, Apidae) with emphasis on the nucleus-flagellum transition region.

The flagellum of Apis mellifera (Hymenoptera, Apidae) consists of two mitochondrial derivatives, an axoneme and two accessory bodies. The mitochondrial derivatives are of unequal size and lie parallel to the axoneme. In the larger derivative four regions can be distinguished while in the smaller, only three. The region occurring only in the larger derivative consists of paracystalline material. The smaller mitochondrial derivative terminates anterior to the larger one. An extremely long centriolar adjunct is observed between the nucleus and the smaller mitochondrial derivative. This adjunct is compact, very electron dense and gradually tapers from base toward apex, finishing at the anterior extremity of the axonemal microtubules. In this flagellar region, there is only one accessory body present between the larger mitochondrial derivative and the axoneme. Anteriorly, the tips of the axonemal microtubules are inserted in a well developed mass of granular appearance. This material surrounds the nuclear base, separating it from the anterior end of the larger mitochondrial derivative. We believe that the structure identified here as a centriolar adjunct is homologous to that observed in Formicidae, Ichneumonoidea and Symphyta. Therefore, very probably, it is common to most Hymenoptera.

Microfibrils: neglected components of pressure-bearing tendons.

Some tendons wrap around joints and receive compressive forces besides transferring the tension forces from muscle to bone. These tendons develop a fibrocartilaginous structure which enables them to withstand pressure. This article describes the existence and distribution of microfibrils (or preelastic fibers) in the pressure-bearing tendons of rabbits and dogs by the application of histochemical assays and transmission electron microscopy. Rabbit and dog tendons possess no mature elastic fibers. The rabbit tendon exhibits some response to Weigert's method prior to oxidation which indicates the existence of the so-called elaunin fibers, especially in the pressure zone. Oxidation with peracetic acid or oxone discloses intricate aspects of the oxytalan fiber distribution in both tension and pressure zones of the dog and rabbit tendons. Bundles of 12 nm microfibrils were demonstrated in the rabbit tendon by electron microscopy after fixation in the presence of tannic acid. The existence of preelastic fibers in the pressure-bearing tendons has been neglected and they are assumed to have importance in the microarchitecture of the tissue and in the ability of the tendon to support tension and compression forces.