Histological description of the skin glands of Phyllobates bicolor (Anura: Dendrobatidae) using three staining techniques / Descripción histológica de las glándulas cutáneas de Phyllobates bicolor (Anura: Dendrobatidae) usando tres técnicas de tinción

The mechanisms to obtain and store skin toxins in frogs in of the family Dendrobatidae are not completely understood. In order to contribute to understand how toxins are stored, we provide a histological description of the cutaneous glands of the species Phyllobates bicolor. The skin of two adult frogs was examined through three histological staining techniques (hematoxilin-eosin, PAS and Masson Trichrome) using conventional optic microscopy. The skin of Phyllobates bicolor contains two types of exocrine glands: mucous and serous, which empty their products to the epidermal surface through an intra-epithelial duct that leads to a stoma. The mucous and serous glands and the intercalated ducts are surrounded by a discontinuous sheath of myoepithelial cells, which colapse the lumen of the acinus and the lumen of ducts and facilitate the secretion and release of their content. The serous glands have a polarized syncytium of tall cuboidal or columnar epithelial cells. Both glands have a mixed secretion, thus, the contents of mucous glands tend to be neutral and basophilic, while the contents of the serous glands are basophilic and acidophilic.

A la fecha no existe mayor información con respecto a los mecanismos para obtener y almacenar las toxinas cutáneas de ranas de la familia Dendrobatidae. Con el fin de contribuir y entender cómo son almacenadas estas toxinas, realizamos una descripción histológica de las glándulas cutáneas de la especie Phyllobates bicolor. La piel de dos ranas adultas se examinó mediante tres técnicas de tinción histológica (hematoxilina-eosina, PAS y tricrómico de Masson) mediante microscopía óptica convencional. La piel de P. bicolor contiene dos tipos de glándulas exocrinas: mucosas y serosas, que vierten sus productos a la superficie epidérmica a través de un conducto intra-epitelial que conduce a un estoma. Las glándulas mucosas, serosas y los conductos intercalados están rodeados por una funda discontinua de células mioepiteliales, las que colapsan el lumen de los acinos y conductos, facilitando la secreción y liberación de su contenido. Las glándulas serosas tienen un sincitio polarizado de células epiteliales columnares cúbicas. Ambas glándulas tienen una secreción mixta, por lo tanto, los contenidos de las glándulas mucosas tienden a ser neutral y basófilas, mientras que los contenidos de las glándulas serosas son basófilas y acidófilas.

Morphological and morphometrical assessment of spermathecae of Aedes aegypti females

The vectorial capacity of Aedes aegypti is directly influenced by its high reproductive output. Nevertheless, females are restricted to a single mating event, sufficient to acquire enough sperm to fertilize a lifetime supply of eggs. How Ae. aegypti is able to maintain viable spermatozoa remains a mystery. Male spermatozoa are stored within either of two spermathecae that in Ae. aegypti consist of one large and two smaller organs each. In addition, each organ is divided into reservoir, duct and glandular portions. Many aspects of the morphology of the spermatheca in virgin and inseminated Ae. aegypti were investigated here using a combination of light, confocal, electron and scanning microscopes, as well as histochemistry. The abundance of mitochondria and microvilli in spermathecal gland cells is suggestive of a secretory role and results obtained from periodic acid Schiff assays of cell apexes and lumens indicate that gland cells produce and secrete neutral polysaccharides probably related to maintenance of spermatozoa. These new data contribute to our understanding of gamete maintenance in the spermathecae of Ae. aegypti and to an improved general understanding of mosquito reproductive biology.

The metasternal and Brindley's Glands of Triatoma brasiliensis Neiva (Hemiptera: Reduviidae) / Glândulas de Brindley e metasternal de Triatoma brasiliensis Neiva (Hemiptera: Reduviidae)

Triatoma brasiliensis Neiva is the most important vector of the Chagas' disease in the semiarid zones of North-eastern Brazil. Adult bugs have two main pairs of exocrine glands, the metasternal and the Brindley's glands, which release volatiles possibly with defense, alarm and/or mating functions. To date, anatomical and histological studies of the metasternal and the Brindley's glands in the genus Triatoma are scarce and, considering the relevance of these exocrine glands, the present work aimed at studying their morphology in T. brasiliensis. The metasternal and the Brindley's glands of T. brasiliensis consist of glandular units similar to those described for Rhodnius prolixus Stål and Panstrongylus megistus Burmeister, comprising a secretory apparatus, saccule and collector duct.

Triatoma brasiliensis Neiva é o principal inseto vetor da doença de Chagas no Nordeste do Brasil. Os adultos da espécie apresentam dois pares de glândulas exócrinas, as glândulas metasternais e as glândulas de Brindley que liberam compostos voláteis, possivelmente com função de defesa, alarme e/ou acasalamento. O conhecimento anatômico e histológico das glândulas de Brindley e metasternal no gênero Triatoma é escasso e, considerando a relevância dessas glândulas na sua biologia, o objetivo do presente trabalho foi estudar e conhecer a sua morfologia. As glândulas de Brindley e metasternal de T. brasiliensis possuem uma unidade glandular similar àquela descrita para Rhodnius prolixus Stål e Panstrongylus megistus Burmeister, formada principalmente por um aparato secretor, sáculo e ducto coletor.

Histochemical and ultrastructural evidence of lipid secretion by the silk gland of the sugarcane borer Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae)

The silk gland in Lepidoptera larvae is responsible for the silk production used for shelter or cocoon construction. The secretion of fibroin and sericin by the different silk gland regions are well established. There are few attempts to detect lipid components in the insect silk secretion, although the presence of such element may contribute to the resistance of the shelter to wet environment. This study characterizes the glandular region and detects the presence of lipid components in the secretion of the silk gland of Diatraea saccharalis(Fabricius). The silk gland was submitted to histochemical procedure for lipid detection or conventionally prepared for ultrastructural analyses. Lipid droplets were histochemically detected in both the apical cytoplasm of cell of the anterior region and in the lumen among the microvilli. Ultrastructural analyses of the anterior region showed lipid material, visualized as myelin-like structures within the vesicular Golgi complex and in the apical secretory globules, mixed up with the sericin; similar material was observed into the lumen, adjacent to the microvilli. Lipids were not detected in the cells neither in the lumen of the posterior region. Our results suggest that the silk produced by D. saccharalis has a minor lipid content that is secreted by the anterior region together with the sericin.

A glândula da seda de larvas de Lepidoptera é responsável pela produção da seda usada na construção do casulo ou do abrigo. A secreção de fibroína e sericina pelas diferentes regiões da glândula da seda está bem estabelecida. Existem poucos trabalhos tentando identificar componentes lipídicos na secreção de seda de insetos, embora a presença desse componente contribua para a resistência da seda a ambiente úmidos. Este estudo teve como objetivo identificar a presença de componente lipídico na secreção da glândula da seda de larvas de Diatraea saccharalis (Fabricius), bem como caracterizar a região glandular responsável pela secreção. A glândula da seda foi submetida a procedimentos histoquímicos para detecção de lipídeos e convencionalmente preparada para análise ultra-estrutural. Gotas lipídicas foram histoquimicamente detectadas no citoplasma apical de células da região anterior e no lúmen, entre os microvilos. A análise ultra-estrutural da região anterior mostrou material lipídico, visualizado como figuras do tipo mielina dentro do complexo de Golgi vesicular e nos glóbulos secretores apicais, misturados com sericina; material semelhante foi observado dentro do lúmen, adjacente aos microvilos. Nenhum componente secretor lipídico foi detectado nas células ou no lúmen da região posterior. Os resultados sugerem que a seda produzida pela D. saccharalis tem, pelo menos, um discreto componente lipídico, que é secretado pela região anterior, junto com a sericina.

Reproductive behavior of Eidmanacris corumbatai Garcia (Orthoptera: Phalangopsidae)

Adult males of Eidmanacris corumbatai Garcia have reduced tegmina without stridulatory apparatus. For this reason, they developed other means of intra-specific communication. During courtship, the males use a combination of foreleg drumming and waving of the antennae, in addition to chemical signaling through pheromones. The females become receptive to copulation when the males expose their metanotal gland. This gland, located on the male metanotum, is also a source of substances on which females feed before receiving the spermatophore. During copulation, the female destroys the apex of the metanotal gland to gain access to the secretion released by this structure.

Em Eidmanacris corumbatai Garcia, os machos adultos apresentam tegminas reduzidas e sem aparelho estridulatório e, portanto, tiveram que desenvolver outros modos de comunicação intra-especifica. Durante a corte, os machos usam uma combinação de batimentos com as pernas dianteiras e ondulações das antenas, além da sinalização química através de feromônios, uma vez que as fêmeas se tornam receptivas à cópula quando os machos expõem a glândula metanotal. Essa glândula, localizada no metanoto do macho, é também uma fonte de substâncias das quais a fêmea se alimenta antes de receber o espermatóforo. Durante a cópula, a fêmea destrói o ápice da glândula metanotal para ter acesso à secreção liberada por essa estrutura.

Ultrastructural modifications in the venom glands of workers of Apis mellifera L. (Hymenoptera: Apidae) promoted by topical application of juvenile hormone

The present study analyzed, the influence of the treatment with juvenile hormone on the ultrastructure of Apis mellifera L. workers' venom glands. Newly emerged workers received topical application of 1 æl of juvenile hormone diluted in hexane, in the concentration of 2 æg/æl. Two controls were used; one control received no treatment (group C1) and other received topical application of 1 æl of hexane (group C2). The aspect of the glandular cells, in not treated newly emerged workers, showed that they are not yet secreting actively. Cellular modifications happened according to the worker age and to the glandular area considered. The most active phase of the gland happened from the emergence to the 14th day. At the 25th day the cells had already lost their secretory characteristic, being the distal area the first to suffer degeneration. The treatment with juvenile hormone and hexane altered the temporal sequence of the glandular cycle, forwarding the secretory cycle and degeneration of the venom gland.

O presente estudo analisou, através de estudos ultra-estruturais a influência do tratamento com hormônio juvenil sobre as glândulas de veneno de operárias de Apis mellifera L. Para tanto, operárias recém-emergidas receberam aplicação tópica de 1æl de hormônio juvenil, na concentração de 2 æg/æl, sendo usado o hexano como veículo. Foram feitos dois controles, um que não recebeu nenhum tipo de tratamento (grupo C1) e o outro que recebeu aplicação tópica de 1 æl de hexano (grupo C2). O aspecto das células glandulares, em operárias recém-emergidas, mostra que estas não estão ainda secretando ativamente. Observa-se que alterações celulares ocorrem de acordo com a idade da operária e da região glandular considerada no controle C1. Assim, a fase de secreção mais ativa da glândula ocorre entre a emergência e os 14 dias de idade; aos 25 dias as células já perderam sua característica secretora, sendo a região distal a primeira a sofrer degeneração. Os tratamentos com hormônio juvenil e com hexano alteram a cronologia do ciclo glandular, antecipando o início da secreção e da degeneração da glândula.

Ultramorphological analysis of the venom glands and their histochemical relationship with the convoluted glands in the primitive social paper wasp Polistes versicolor (Hymenoptera: vespiade)

The venom glands are part of the most important defense weapon in Aculeata: the venom apparatus. The arrangement of these glands can vary among species, but in general they are composed of long secretory tubules connected to a muscular sac-like reservoir. Although the occurrence of these variations has been documented, many studies neglected the existence of a well-developed secretory portion in the lumen of the reservoir named convoluted gland. This study is an ultramorphological analysis of the venom glands and their histochemical relationship with the convoluted glands in the primitive social wasp Polistes versicolor. In this wasp, the venom glands are constituted by two tubular portions tha penetrate individually in the venom reservoir, inside of which we can find the convoluted glands. Besides morphological differences in their cells, histochemical analysis of the venom and convoluted glands clearly show differences between them. While the venom glands indicate positive reaction only for proteins, the convoluted glands present positive reaction for proteins, neutral glycoconjugates, and lipids. The secretion of the convoluted gland cells may modify the compounds passing through the embedded tubular region

Morphology and protein patterns of honey bee drone accessory glands

We used light and transmission electron microscopy to examine the morphology of the accessory glands of immature and mature adult males of Apis mellifera L. We also made an electrophoretic analysis of the protein content of the mature gland. The glands of the immature male actively secrete a mucous substance that can be seen in the lumen of the gland of the mature male. This secretion stains with mercury bromophenol blue and with periodic acid-Schiff reaction, which stain glyconjugates. The protein content was higher in the lumen secretion than in the gland wall extracts. The electrophoresis patterns of the wall extracts were different from those of the secretion found in the gland lumen.

Ultrastructure of the Lyonet's glands in larvae of Diatraea saccharalis Fabricius (Lepidoptera: Pyralidae)

The Lyonet's gland is found in Lepidoptera larvae, close to the excretory duct of the silk gland. The role played by this gland is still uncertain. This work aims to describe the ultrastructure of the Lyonet's gland in Diatraea saccharalis larvae, offering suggestions regarding its possible function. The insects were reared under laboratory-controlled conditions. The glands were conventionally prepared for transmission (TEM) and scanning (SEM) electron microscopy. SEM showed that Lyonet's glands are paired small structures located in the ventral side of the head. They are composed by clustered long cells resembling leaves. Under TEM observations, each cell is surrounded by a thin basal lamina and contains large stellate nucleus. The cytoplasm presents large and empty canaliculi with small microvilli. The basal plasma membrane forms numerous infoldings where numerous and well-developed mitochondria are concentrated. The cytoplasmatic membrane system is poorly developed. Our ultrastructural results suggested that the Lyonet's gland in D. saccharalis larvae may be involved in the uptake of small molecules from the hemolymph; no morphological evidences of macromolecules synthesis and secretion were noticed. The detection of nerve fibers in the gland suggest a neural control for the glandular cell function.

Occurrence, morphology and ultrastructure of the Dufour gland in Melipona bicolor Lepeletier (Hymenoptera, Meliponini)

The occurrence, morphology and ultrastructure of the Dufour gland in Melipona bicolor Lepeletier, 1836 are presented. The Dufour gland is not present in workers. In virgin queens the gland cells show characteristics of low activity, which are described in the text. In physogastric queens the gland epithelium is higher and the cells more active than in virgin queens, showing numerous basal plasmic membrane invaginations impregnated by an electrondense material, increased apical invaginations and accumulation of substances that will be released to the gland lumen in the subcuticular space. Therefore, the data show that the Dufour gland is more developed in physogastric than in virgin queens, indicating a possible involvement of the Dufour gland in the reproduction of this species.

Dufour glands in the hymenopterans (Apidae, Formicidae, Vespidae): a review

Associated to the sting apparatus of the aculeate hymenopterans is found the poison gland, originated from the glands associated to the ovipositor of the non-aculeate hymenopterans and the less derived Dufour gland, homologue of the coletterial gland of other insects, and found in all hymenopteran females. The Dufour gland functions is mostly uncertain in hymenopterans but in ants it is involved with communication and defense and in non social bees with the nest building and protection. In wasps possibly with kin-recognition. Differences in morphology and chemical composition of the gland secretion were observed among species, in the same species, between the castes in the social species and among individual of the same caste playing different tasks or belonging to different nest. Its original function of egg-protective substance producing, or favoring the oviposition, appear to have been replaced or complemented in hymenopterans by the production of semiochemicals with function in communication

Exocrine differentiation of trichoepithelioma & desmoplastic trichoepithelioma; a scanning electron microscopic study.

Trichoepithelioma is widely thought to be a benign appendage tumour which arises from hair follicles (i) Scanning electron microscopy reveals that the basement membrane of Trichoepithelioma & desmoplastic Trichoepithelioma is similar to the basement membrane of exocrine glands like sweat or sebaceous gland. The basement membrane of Trichoepithelioma and desmoplastic Trichoepithelioma do not show any difference in their structure. Thus, possibly Trichoepithelioma and desmoplastic Trichoepithelioma arises from exocrine gland and are closely related to each other.

Ultrastructural reappraisal of endometrial glandular changes in women wearing Cu-T200 device for longer duration.

The present communication deals with the effects of Copper-T200 Sq mm intrauterine device on the endometrial glands in the women using it for a longer duration i.e. up 8 years. The ultrastructural changes in the lining endometrial glands were studied during both non-ovulatory and ovulatory phases of the menstrual cycle. The ultrastructural studies demonstrated significant progressive changes in the lining endothelial cells of endometrial glands. The findings showed marked accumulation of glycogen in the cells in secretory phase of the endometrial cycle. Ultrastructural changes in glandular lining cells were more pronounced in women using Cu-IUCD for 4-8 years having distorted morphology with disrupted cell organelles, swollen mitochondria, irregular pattern of microvilli, deposition of electron dense material on cell surface and narrowing of glandular lumen.