Renata Viscuso

Structure of spermatodesms of Orthoptera Tettigonioidea

Examination of spermatodesms collected from the male and female genital tracts of numerous Orthoptera Tettigonioidea revealed an overall morphological and ultrastructural organization that is generally similar in individuals of the same sex but considerably different between males and females of even the same species. In the male genital tracts each spermatodesm is composed of a limited number of spermatozoa whose nuclei and acrosomes are covered by a mucous cap. The spermatozoa inside each bundle are mainly arranged in parallel rows and are always distinctly separate. The number of spermatozoa per spermatodesm may vary within the same individual although it does not seem to exceed a maximum value that we could only determine exactly in Tettigoniidae species. The most characteristic feature of spermatozoa of all the species examined is a conspicuous elongation of the plasma membrane in the acrosomal region that is not present in the female genital tracts. In addition, spermatodesms from females are composed of highly numerous tightly packed spermatozoa that are linked together via the acrosomal region. This characteristic of spermatodesms, never previously reported in other insect species, would involve their reorganization during transfer from the male to the female genital tracts and would seem to take place in the spermatophore. The probable role of spermatodesms in the reproductive physiology of Tettigonioidea might be related to the degree of maturity of the sex cells transferred to the female; the reorganization of the spermatozoa out of the male genital tracts seems to support this hypothesis.

Ultrastructural changes in sperm of Eyprepocnemis plorans (Charpentier) (Orthoptera: Acrididae) during storage of gametes in female genital tract

Summary We studied the sperm changes occurring during storage in the female genital tract of Eyprepocnemis plorans (Orthoptera: Acrididae). In this species the spermatheca consists of a long duct with two terminal diverticula: a preapical one with a U-bend and a straight apical one. After copulation the spermatozoa reach the diverticula where they undergo a peculiar uncoating process which leads to the complete re moval of the glycocalyx. This prepares the spermatozoa to interact with the female gametes. A different role is performed by the two diverticula in sperm storage. In the preapical one most sperm are stored until fertilization of the egg; in the apical diverticulum a limited number of spermatozoa are stored but most are progressively dismantled. These modifications may reduce any excess of spermatozoa or operate a mechanism of selection, aiming to favour sperm from the last mating.

Morphological and ultrastructural organization of the male genital apparatus of some Aphididae (Insecta, Homoptera)

Ultrastructural investigations on the amphigonic reproductive mechanisms in Aphidoidea (Homoptera, Sternorryncha) species, of which little is known in the literature, can provide useful information on their reproductive biology. Morphological and ultrastructural investigations were carried out on the reproductive tract and on spermatozoa from sexually mature males of five species belonging to three subfamilies of Aphidoidea. The organization of the reproductive tract and of spermatozoa appears simple and similar in the examined species. Each testis consists of three follicles containing many cysts arranged in a progressive order of maturation from the distal to the proximal tract; spermiogenesis only occurs in sexually mature males, ending with the organization of sperm bundles. Gametes are neatly arranged in each bundle and kept together by a cap showing a particular organization. The distal tract of each spermiduct is enlarged and full of gametes; close to the testis the two spermiducts merge together, except in Drepanosiphum platanoidis where the spermiducts run independently. The various tracts of each examined gland showed no peculiar differences either in the same species or among the species. Some interesting hypotheses are proposed in this work about the probable roles of the investigated structures in the reproductive mechanisms of these insects.

Structure and function of seminal vesicles of Orthoptera Tettigonioidea

Abstract The epithelium of seminal vesicles of seven species of Orthoptera Tettigonioidea was examined. Results revealed an epithelium that is always monolayered and devoid of cuticular intima, thus reflecting its mesodermic origin. In some species epithelial secretory activity is intense and seems to be effected via both apocrine and merocrine mechanisms. A peculiar characteristic observed in most of the species examined consists in the presence of spermiophagic activity, never previously recorded in insect seminal vesicles which have usually been attributed the function of synthesizing the substances that maintain sperm viable during their storage therein. The probable role of this spermiophagic activity in relation to the reproductive biology of Orthoptera Tettigonioidea is discussed.

Mode of transfer of spermatozoa in Orthoptera Tettigoniidae

A morphological and ultrastructural study was carried out on the spermatophore and spermatodoses of some species of Orthoptera Tettigoniidae. From the results concerning the spermatophore it emerged that this structure has a morphological and ultrastructural organization represented by a dilated ampulla and a peduncle or neck. From the examination of freshly deposited spermatophores and those at various time intervals thereafter, it was seen that these structures other than allowing gamete transfer, represent the site where spermatodesms, organized in the male genital tracts, undergo reorganization to acquire their definitive morphological and structural characteristics as found in the female genital tracts. The spermatodoses, in the same way as the spermatophore, represent capsules containing spermatodesms, which are originated in the spermatheca, their specific morphology seems to diversify according to the species considered. As regards their role, it is hypothesized that these structures represent a long-term conservation mechanism for spermatozoa inside the seminal receptacle.

Spermiolytic activity of the epithelium of the spermathecal duct of Rhacocleis annulata fieber (Orthoptera : Tettigoniidae)

Abstract This study reports, for the first time, lytic activity in the distal and median regions of the spermathecal duct of Rhacocleis annulata Fieber (Orthoptera: Tettigoniidae). Lysis is more pronounced in recently mated females, and appears to take place in a progressive sequence originating in the cells underlying the cuticular intima. These cells exhibit large heterogeneous vesicles resembling lysosomes, which would participate in the partial dismantling of the cuticular intima. Consequently, the sperm found in the lumen of the latter organ penetrate the cells, probably pushed by the pressure exerted on the luminal walls, and then, together with the cells themselves, undergo lysis. Degradation of spermatozoa seems to follow a strict sequence of events, which ends with the dismantling of the microtubules of the axoneme, as reported previously for Locusta (Cantacuzene, 1971) and for some pulmonate gastropods (Bayne, 1970). We propose that lysis is part of the mechanism dealing with capture and subsequent elimination of surplus sperm transferred to the female during copulation. Accordingly, fertilization activity would occur exclusively within the seminal receptacle. No evidence of a similar phenomenon in the latter organ has previously been reported for Rhacocleis annulata.

Morphological and ultrastructural organization of the spermatheca of some Tettigoniidae (Insecta, Orthoptera)

Abstract A morphological and ultrastructural study of the spermatheca of some species of Orthoptera Tettigoniidae was carried out to understand the role of this female organ in the reproductive biology because no literature exists about it in this insect group. In all the examined species, the spermatheca is of ectodermal origin and is composed of a seminal receptacle, mainly involved in the collection and storage of the spermatozoa, and of a spermathecal duct. In both these organs, the epithelium of the wall is made up of two different cell types: cuticle-forming cells, underlying the cuticular intima, and gland cells. Both of these cell types have secretory features that differ among the species and also within the same species, in relation to the tracts examined. In particular, the ultrastructure of the distal tract of the spermathecal duct indicates a more marked secretory activity than in the other tracts of the duct. This activity is often accompanied by ultrastructural aspects, suggesting a lysis activity in both the epithelium and the upper cuticle. Based on these findings, it is hypothesized that the seminal receptacle and the spermathecal duct have different functional roles, despite having a similar general structural organization.

Structure of male accessory glands of Bolivarius siculus (fischer) (Orthoptera, Tettigoniidae) and protein analysis of their secretions.

In Tettigoniidae (Orthoptera), male reproductive accessory glands are involved in the construction of a two‐part spermatophore; one part, the spermatophylax, is devoid of sperm and considered a nuptial gift. The morphology, ultrastructure, and secretion protein content of the male reproductive accessory glands from Bolivarius siculus were investigated. Two main groups of gland tubules open into the ejaculatory duct: the “first‐order” glands, a number of large anterior tubules, and the “second‐order” glands, smaller and more numerous tubules positioned posteriorly. Along with a further subdivision of the gland tubules, we here describe for the first time an additional gland group, the intermediate tubules, which open between first and second‐order glands. The mesoderm‐derived epithelium of all glands is a single layer of microvillated cells, which can be either flattened or cylindric in the proximal or distal region of the same gland. Epithelial cells, very rich in RER and Golgi systems, produce secretions of both electron‐dense granules and globules or electron‐transparent material, discharged into the gland lumen by apocrine or merocrine mechanisms, respectively. With one exception, a unique electrophoresis protein profile was displayed by each of the gland types, paralleling their unique morphologies. To assess the contribution of different types of accessory glands to the construction of the spermatophore, the protein patterns of the gland secretions were compared with those of the extracts from the two parts of the spermatophore. All samples showed bands distributed in a wide range of molecular weight, including proteins of very low molecular mass. However, one major high molecular weight protein band (>180 kDa) is seen exclusively in extracts from the first‐order glands, and corresponds to an important protein component of the spermatophylax. J. Morphol., 2009.

Sperm storage by spermatodoses in the spermatheca of Trioza alacris (Flor, 1861) hemiptera, psylloidea, triozidae: A structural and ultrastructural study

Female insects generally store sperm received during mating in specific organs of their reproductive tract, i.e., the spermathecae, which keep the sperm alive for a long time until fertilization occurs. We investigated spermatheca morphology and ultrastructure in the psylloidean insect Trioza alacris (Flor, 1861 ) in which spheroidal sperm packets that we refer to as ‘spermatodoses’ are found after mating. The ectoderm‐derived epithelium of the sac‐shaped spermatheca that has a proximal neck, consists of large secretory and flat cuticle‐forming cells. Secretory cells are characterized by a wide extracellular cavity, bordered by microvilli, in which electron‐dense secretion accumulates before discharge into the spermathecal lumen. The cuticle‐forming cells produce the cuticular intima of the organ and a peculiar specialized apical structure, through which secretion flows into the lumen. At mating, the male transfers bundles of sperm cells embedded in seminal fluid into the spermathecal neck. Sperm cells proceed towards the spermathecal sac lumen, where they are progressively compacted and surrounded with an envelope that also encloses secretions of both male and female origin. We describe the formation of these sperm containing structures and document the contribution of the female secretion to spermatodose or female‐determined spermatophore construction. We also discuss the choice of the term ‘spermatodose’ for T. alacris and suggest it be used to refer to sperm masses constructed in the female reproductive organs, at least when they involve the contribution of female secretion.

Ultrastructural organization of the seminal vesicles of Baculum thaii (Phasmida, Phasmatidae) during sexual maturity

Abstract A morphological and ultrastructural study was carried out on the seminal vesicles of Baculum thaii removed from individuals killed at 4, 10 and 20 days from the imaginai moult, with the intention of showing any modifications that these structures undergo during sexual maturity. From the comparative examination, clear evidence was found of epithelial transformations of these organs during sexual maturity: there was a gradual increase in cellular volume accompanied by a progressive development of the apparatus of synthesis. The most particular characteristics, however, in the individuals killed at 10 and 20 days from the moult were, in addition to a marked secretory activity, the presence of spermiophagic activity, which had never been found in the genital tracts of this order of insects. In the light of these results, it can be affirmed that the seminal vesicles of B. thaii, apart from being the site of the secretory activity necessary for maintaining the sperm in this area, also assume an important role in the processes of “controlling” and “regulating” sexual material that is kept ready for transfer to the female genitalia.