Ultrastructure of germ cells,Sertoli cells and mitochondria during spermatogenesis in mature testis of the Chinese Taihang black goats (Capra hircus)

The objective of this study was to describe the ultrastructure of germ cells, Sertoli cells and mitochondria in mature testis of the Chinese Taihang black goat. The characteristics of germ cell nucleus and mitochondria changing during spermatogenesis were investigated by transmission electron microscopy (TEM). The results showed that the spermatogonium was elliptical, and its nucleus was about 4–5 μm. The round mitochondria can be observed throughout the cytoplasm around the nucleus. Small patches of heterochromatin were distributed throughout the nucleus. Spermatocyte was oval-shaped with a nucleus of about 4–4.5 μm in diameter. The heterochromatin began to attach to the inner surface of the nuclear membrane. Spermatid was about 4 μm and oval in shape. Its nucleus was oval or round and approximately 2–3 μm in diameter. The borderline between nucleus membrane and karyoplasm was distinct. During spermiogenesis, spermatid nucleus was condensed and elongated, and chromatin reached the highest condensation in the mature spermatozoon. The mid-piece was surrounded by mitochondria at the neck region. The sperm tail showed the typical “9 + 2″ structure, contained axoneme and central singlet microtubules. The nuclei of the Sertoli cells were irregular shaped and showed indentations in the membrane. In the mature testes of goat bucks, abundant mitochondria were around the germ cells and Sertoli cells. The scattered mitochondria were aggregated around the base of the flagellum (axoneme) during the spermatid differentiation stage. In conclusion, the present study showed that the spermatogenic process of Taihang black goat followed the pattern of mammals with some specific.     

Echolocation call intensity and directionality in flying short-tailed fruit bats, Carollia perspicillata (Phyllostomidae)

The directionality of bat echolocation calls defines the width of bats' sonar "view," while call intensity directly influences detection range since adequate sound energy must impinge upon objects to return audible echoes. Both are thus crucial parameters for understanding biosonar signal design. Phyllostomid bats have been classified as low intensity or "whispering bats," but recent data indicate that this designation may be inaccurate. Echolocation beam directionality in phyllostomids has only been measured through electrode brain-stimulation of restrained bats, presumably excluding active beam control via the noseleaf. Here, a 12-microphone array was used to measure echolocation call intensity and beam directionality in the frugivorous phyllostomid, Carollia perspicillata, echolocating in flight. The results showed a considerably narrower beam shape (half-amplitude beam angles of approximately 16° horizontally and 14° vertically) and louder echolocation calls [source levels averaging 99 dB sound pressure level (SPL) root mean square] for C. perspicillata than was found for this species when stationary. This suggests that naturally behaving phyllostomids shape their sound beam to achieve a longer and narrower sonar range than previously thought. C. perspicillata orient and forage in the forest interior and the narrow beam might be adaptive in clutter, by reducing the number and intensity of off-axis echoes.     

Ultrastructure of the ommatrichia in Megaselia scalaris (Loew) (Diptera: Phoridae)

Using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the ommatrichia, or hair-like processes that are located between the facets of the compound eye, were examined on an adult male Megaselia scalaris (Loew) fly. Each ommatrichium was observed to be a tapering structure bearing a longitudinally grooved cuticle and are anchored tightly in flexible sockets. Ultrathin sectioning and TEM revealed a thick wall in the ommatrichia, and their function was proposed to be mechanoreception based on characteristics from both SEM and TEM observations.     

Chromatoid body: remnants of nucleolar proteins during spermatogenesis in triatomine (Heteroptera, Triatominae)

In this study, we analyzed fibrillarin nucleolar protein expression in CBs of spermatogenic cells from testicular follicles of Triatoma sordida and Triatoma infestans. In the structural and ultrastructural analysis, it was used impregnation by silver ions, immunocytochemistry, immunofluorescence and transmission electron microscopy using antibodies against fibrillarin. Regarding the results, the fibrillarin nucleolar protein marked the nucleus and some cytoplasmic spots of germ cells during spermatogenesis in triatomines. These data suggest that fibrillarin could be a constituent of the CB that was most likely derived from nucleolar fragmentation. This is the first time that fibrillarin protein expression has been shown in the CB during spermatogenesis progression in triatomines. The knowledge regarding CB constituents may help to expand the understanding of the physiological role of this structure and the role that it plays in the reproductive biology of triatomines, which are vectors of Chagas Disease.     

Ultrastructural study of spermiogenesis and the spermatozoon of Cavisoma magnum (Southwell, 1927) (Acanthocephala, Palaeacanthocephala, Cavisomidae), from Siganus lineatus (Pisces, Teleostei, Siganidae) (Valenciennes, 1835) in New Caledonia

This paper presents an ultrastructural study of Cavisoma magnum (Acanthocephala, Cavisomatidae) with a Transmission Electron Microscopy tool. This parasite of the fish Siganus lineatus is here reported for the first time from off New Caledonia, South Pacific. It is the first study describing the ultrastructure, spermiogenesis and spermatozoon of a species of the family Cavisomatidae. The young spermatid of C. magnum possesses a centriole constituted of doublets without a central element. After the elaboration of a flagellum of 9+2 pattern, the centriole migrates in a nuclear groove. Then the flagellum migration occurs and gives rise to a spermatozoon. The distribution and the size of the protein granules are reported and the posterior extremity appears like a chromatin lamina wave. Comparative ultrastructural data are presented on sperm and spermiogenesis of the Acanthocephala and Rotifers examined to date and the phylogenetic implications are discussed.     

Ultrastructure and morphometry of the egg of Psorophora albigenu Lutz, 1908 (Diptera: Culicidae)

Eggs of Psorophora albigenu were analyzed by light and scanning electron microscopy. Eggs were laid singly and were black and elliptical in outline. A length of approximately 586.4 ± 10.83 μm, a width of 172.3 ± 8.09 μm (n=30), and an egg index (length/width ratio) of 3.33 were observed. The anterior extremity tapered abruptly from a width of 64.9 μm, while such tapering was more gradual at the posterior extremity from a width of 77.4 μm. The ventral surface of the chorionic coating presented cells with tubular aspect containing tubercles in rows with a density of 9-16 tubercles per cell. These tubercles presented two different sizes, with the largest measuring 7.87 ± 01.58 μm and the smallest measuring 0.71 ± 0.53 μm (n=30) in longitudinal diameter. The micropyle orifice was very evident, with a diameter of 3.36 μm. The morphometric characteristics of Ps. albigenu obtained in this study were distinct from those of other species of the Psorophora genus, including Psorophora varipes which has been considered for a long time to be synonymous with Ps. albigenu.     

Ultrastructure of the female reproductive apparatus of the egg parasitoid Gryon pennsylvanicum (Ashmead) (Hymenoptera,Platygastridae)

The growing interest in Leptoglossus occidentalis, the conifer seed bug pest accidentally introduced into Europe in the 1990s, led us to investigate the female reproductive structures of the hymenopteran platygastrid Gryon pennsylvanicum, which is its candidate antagonist for biological control programmes. Our study revealed a genital apparatus with some characteristic features, such as an unusual length of the oviduct (divided into a long proximal and a short distal tract), the absence of accessory glands and the presence of a spermatheca provided with a small spermathecal gland. The ultrastructural investigation revealed that the shorter part of the common oviduct is involved in ion uptake whereas the longer part has two cell types with secretory function: the former with dense bodies and the latter with granular particles. The secretory contents of both are released into the oviduct lumen. The granular particles are formed in a complex of modified endoplasmic reticulum and appear as virus-like particles.     

Ultrastructure of the seminal vesicle and sperm storage in Panorpidae (Insecta: Mecoptera)

The histology and ultrastructure of the seminal vesicle, male accessory gland and the epididymis in Panorpa and Sinopanorpa were observed using light microscopy and scanning and transmission electron microscopy. The seminal vesicle consists of a mono-layered elongated columnar epithelium, which contains abundant electron-dense granules and secretory vesicles, and a small central lumen. In the apical region of the epithelium of the seminal vesicle, the intense secretory activity seems to be effected by means of merocrine mechanisms. The epithelium of the accessory gland is rich in rough endoplasmic reticulum and Golgi complex, and secretes seminal fluid into the lumen via both apocrine and merocrine mechanisms. The seminal vesicle is similar to the accessory gland in the epithelium structure and their secretory activity, mainly serving a secretory function rather than storing sperms. Instead, the sperms are stored in the epididymis, whose epithelium secretes nutrients into the large lumen by merocrine mechanisms. The secretory activity and function of the seminal vesicle are briefly discussed.     

Ultrastructure of the compound eyes in the hangingfly Bittacus planus Cheng (Mecoptera: Bittacidae)

The ultrastructure of the apposition eyes in the hangingfly Bittacus planus Cheng was investigated using transmission electron microscopy. The compound eyes are composed of approximately 1000 contiguous ommatidia, each of which consists of a biconvex cornea, a crystalline cone, eight retinula cells, two primary pigment cells, and 12 secondary pigment cells. The rhabdom is of fused-type and formed by the rhabdomeres from eight retinula cells that run from the cone to the basal lamina, although the rhabdomere from the basal retinula cell (R8) only contributed to the lowest part of the rhabdom. The pigment granules are spread evenly in the primary pigment cells but are concentrated at the proximal and distal ends in the secondary pigment cells, and close to the rhabdom in retinula cells. The rhabdom is peculiar for the presence of gaps at the outer corner of each two adjoining rhabdomeres in different levels of retinula cell except for the proximal zone.     

Ultrastructure of the Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) midgut

The insect midgut has ultimately been the focus of researches tempting to control insect pests because alterations in the insect gut may affect not only its development, but also physiological events such as nutrient absorption and transformation. The objective of the present work was to describe morphologically, histochemically, and ultrastructurally the larva midgut of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), a cotton key pest in Brazil. Light and electronic transmission microscopy was used to obtain images from midgut sections of late fourth-instar larvae of A. argillacea. In general, the morphology, histochemistry, and ultrastructure characteristics of A. argillacea midgut follow that described in the literature for other lepidopteran species. However, the results showed a mitochondrial polymorphism and branched microvilli, which suggest an ultrastrucutural and physiological modification possibly associated with a high absorption and secretion activity by the columnar cells of this species. This intense activity may favor a faster response related to the action of ingested microbial agents and/or toxins, and can explain the high susceptibility of A. argillacea to the agents of control such as the toxin of Bacillus thuringiensis.     

Ultrastructure of the mature testicular vesicle of Pseudonannolene tocaiensis Fontanetti, 1996 (Diplopoda, Pseudonannolenidae)

The mature testicular vesicles of the species Pseudonannolene tocaiensis have three portions: a peripheral portion; a central portion that is typically secretory and between these two an intermediary portion, a lumen filled with spermatozoa. Both secretory and peripheral portions present the same type of cells. The ultrastructural analysis of the peripheral portion suggests it is involved in hormone synthesis. The secretory portion probably contributes to the production of spermatic fluid, compensating for the absence of male accessory glands in this species.     

Ultrastructure of the mature spermatozoon of the bivalve Scapharca broughtoni (Mollusca: Bivalvia: Arcidae)

The ultrastructure of mature spermatozoa of the giant clam bivalve Scapharca broughtoni was investigated by transmission electron microscopy for the first time. The mature spermatozoon consists of a head which is composed of a cone-shaped acrosome, a round nucleus, and a tail region. A subacrosomal space contains an axial rod and a basal plate, the latter lying between the acrosome and the nucleus. Although the nucleus lacks an anterior invagination, an inverted shallow V-shaped posterior invagination is present within the nucleus. Within the middle portion of the spermatozoon lie five spherical mitochondria while the long whip-like end portion is composed of an axoneme with the typical 9 + 2 structure. Our conclusion is that the spermatozoon of S. broughtoni is of the type I anacrosomal “aquasperm”, and the morphology of acrosome and nucleus are an adaptation to external fertilization.     

Ultrastructure of dorsal ocelli of the short-faced scorpionfly Panorpodes kuandianensis (Mecoptera: Panorpodidae)

Dorsal ocelli are important visual organs of insects to perform a variety of behavioral functions. However, the fine structure of ocelli has not been studied in many groups of insects. In this paper the ocellar ultrastructure of the short-faced scorpionfly Panorpodes kuandianensis was investigated using light microscopy and scanning and transmission electron microscopy. The adult of P. kuandianensis possesses one median and two lateral ocelli. Each ocellus comprises a cornea, a layer of corneagenous cells, a clear zone, a retina, and pigment cells. The cornea assumes a domed shape. Under the layer of corneagenous cells is a clear zone, which differs greatly between the median and lateral ocelli, implying they may be divergent in function. The retina comprises elongated retinula cells, which are divided into three regions: a distal rhabdomal region, a middle cytoplasmic region, and a proximal axonal region. In the distal rhabdomal region, most of the rhabdoms are formed by rhabdomeres of two adjacent retinula cells; some are formed by three or four retinula cells. The middle cytoplasmic region comprises the retinula cell segments with nuclei but free of rhabdom. Pigment granules are present among the retinula cells. In the proximal axonal region all retinula cells transform to axons, which synapse with the dendrites of second-order neurons at the base of the ocelli. The relationships among Panorpodidae, Panorpidae and Bittacidae are discussed based on ocellar structure.     

Ultrastructure and heteromorphism of spermatozoa in five species of bugs (Pentatomidae: Heteroptera)

Pentatomidae is one of the largest Heteroptera families, comprising about 10% of the species estimated for the suborder. In spite of existing studies, doubts remain regarding the systematics of Pentatomomorpha. In this study, five species of Pentatomidae spermatozoa were examined to achieve characteristics that enable inferences in the phylogeny of the group and in behavioral issues associated with the presence of polymorphisms. Spermatozoa polymorphisms, characterized by two classes of sizes, are found in Podisus nigrispinus, Podisus distinctus, and Brontocoris tabidus, whereas Thynacanta marginata (Dallas) and Supputius cincticeps have single-size spermatozoa. The head region consists of an acrosome, a nucleus, and part of the centriolar adjunct. In the more anterior region, the nucleus is parallel to the centriolar adjunct. In the nucleus-flagellum transition region, the nucleus overlaps the anterior region of the mitochondrial derivatives, just above the axoneme. The mitochondrial derivatives and the axoneme run the entire extent of the flagellum. In species in which the spermatozoa are polymorphic, the larger spermatozoa have derivatives mitochondrial approximately 3-fold larger than the smaller spermatozoa. Characteristics derived from the morphology of spermatozoa indicate synapomorphies and are promising for systematic studies.     

Ultrastructure of the sensilla on larval antennae and mouthparts in the peach fruit moth, Carposina sasakii Matsumura (Lepidoptera: Carposinidae)

The ultrastructure of the sensilla on the larval antennae and mouthparts of the peach fruit moth, Carposina sasakii Matsumura, were investigated using scanning electron microscopy. On each three-segmented antenna, the basal scape is devoid of sensilla, the pedicel possesses two sensilla chaetica and three sensilla basiconica, and the terminal flagellum carries distally one sensillum styloconicum and three sensilla basiconica. The labrum bears six pairs of sensilla chaetica; the epipharynx carries two pairs of small epipharyngeal sensilla, three pairs of flattened sensilla chaetica, and a pair of broad sensillum digitiformium. Each dentate mandible carries two sensilla chaetica basally on its outer face. On the maxillae, the cardo and stipes each carry a sensillum chaeticum distally; each galea has three elongate flattened sensilla basiconica, two short sensilla chaetica, and two large sensilla styloconica. The distal segment of the maxillary palp possesses distally seven sensilla basiconica and one sensillum styloconicum, and laterally one sensillum digitiformium and one sensillum placodeum. Each labial palp bears distally a short cone-shaped sensillum chaeticum and an elongate slender sensillum styloconicum. The possible functions of these sensilla in the feeding process are briefly discussed.     

The midgut of Cephalotes ants (Formicidae: Myrmicinae): Ultrastructure of the epithelium and symbiotic bacteria

The ultrastructural analysis of the midgut of Cephalotes atratus, C. clypeatus, and C. pusillus reveled that the midgut epithelium lays on a basal lamina and is composed basically of three cell types: digestive cells, regenerative cells, and goblet cells. In these ants, the rough endoplasmic reticulum, in addition to producing digestive enzymes, is involved in the formation of concretions and ion storage in specialized vacuoles present in the midgut. These concretions are spherocrystals and may contribute to stabilize the pH and to maintain symbiotic bacteria found between microvilli. The ultrastructure analysis of these bacteria revealed the presence of a double envelope typical of gram-negative bacteria. For the three species examined, the ultrastructure similarities are conspicuous, suggesting that this may be the pattern for the genus Cephalotes. Details of the relationship between bacteria and microvilli were examined.     

Ultrastructure of antennal sensilla of an autoparasitoid Encarsia sophia (Hymenoptera: Aphelinidae)

Encarsia sophia (Hymenoptera: Aphelinidae) is a parasitoid utilized for biological control of Bemisia tabaci, with selection of prey aided by chemoreceptor organs. The morphology and distribution of the antennal sensilla (chemoreceptors) of E. sophia were examined using Transmission electron micrographs. The total antennal length for E. sophia was 429.28 ± 0.95 μm for females and 437.19 ± 8.21 for males, and each antennae was found to consist of seven sensilla of different types. Both sexes possessed sensilla chaetica, sensilla trichodea, basiconic capitate peg sensilla, multiporous grooved-surface placoid sensilla (MG-PS), uniporous rod-like sensilla, nonporous finger-like sensilla, and sensilla coeloconica. Transmission electron micrographs of longitudinal sections of female antennae showed that they were composed of fat body, cuticle, mesoscutello-metanotal muscles, neurons, and glandular tissue, and cross-sections of the basal MG-PS showed sensillar lymph cavities and dendrites. The MG-PSs were imbedded in an electron-dense mass with cuticular invaginations which acted as pores that connected to a central lumen. The possible function of each type of sensilla is discussed.     

Ultrastructure and composition of cell wall appositions in the roots of Asplenium (Polypodiales)

Cell wall appositions (CWAs), formed by the deposition of extra wall material at the contact site with microbial organisms, are an integral part of the response of plants to microbial challenge. Detailed histological studies of CWAs in fern roots do not exist. Using light and electron microscopy we examined the (ultra)structure of CWAs in the outer layers of roots of Asplenium species. All cell walls studded with CWAs were impregnated with yellow-brown pigments. CWAs had different shapes, ranging from warts to elongated branched structures, as observed with scanning and transmission electron microscopy. Ultrastructural study further showed that infecting fungi grow intramurally and that they are immobilized by CWAs when attempting to penetrate intracellularly. Immunolabelling experiments using monoclonal antibodies indicated pectic homogalacturonan, xyloglucan, mannan and cellulose in the CWAs, but tests for lignins and callose were negative. We conclude that these appositions are defense-related structures made of a non-lignified polysaccharide matrix on which phenolic compounds are deposited in order to create a barrier protecting the root against infections.     

Affect cues in vocalizations of the bat, Megaderma lyra, during agonistic interactions

Some features of emotional prosody in human speech may be traced back to affect cues in mammalian vocalizations. The present study addresses the question whether affect intensity, as expressed by the intensity of behavioral displays, is encoded in vocal cues, i.e., changes in the structure of associated calls, in bats, a group evolutionarily remote from primates. A frame-by-frame video analysis of 109 dyadic agonistic interactions recorded in approach situations was performed to categorize displays into two intensity levels based on a cost-benefit estimate. M. lyra showed graded visual displays accompanied by specific calls and response calls of the second bat. A sound analysis revealed systematic changes of call sequence parameters with display level. At the high intensity level, total call duration, number of syllables within a call, and the number of calls within a sequence were increased, while intervals between call syllables were decreased for both call types. In addition, the latency of the response call was shorter, and its main syllable-type durations and fundamental frequency were increased. These systematic changes of vocal parameters with affect intensity correspond to prosodic changes in human speech, suggesting that emotion-related acoustic cues are a common feature of vocal communication in mammals.