Anatomical and histological studies of the alimentary canal of adult maize leaf weevil,Tanymecusdilaticollis Gyllenhal, 1834 (Coleoptera: Curculionidae)

In this study, ananatomical and histological study was conducted on the alimentary canal of Tanymecusdilaticollis (Coleoptera: Curculionidae), which is an economic polyphagous pest species, to study the relationship between the structure of the alimentary canal and the feeding habit. Therefore, the structure of the alimentary canal of T. dilaticollis was examined using light and electron microscopies. Results have shown that the alimentary canal in T. dilaticollis is consisted of three separate regions as foregut, midgut, and hindgut structurally between the mouth and the anus, which pass from head, thorax, and abdomen. The foregut consists of pharynx, esophagus, crop and proventriculus and in the crop part, expansion is seen compared to other foregut parts. Midgut of T. dilaticollis is the largest part of digestion system. The anterior region of midgut is twofolds wider than the posterior region. The posterior midgut extends tubularly and it is connected to eightgastric caeca. The hindgut of T. dilaticollis consists of fourparts as pylorus, ileum, colon, and rectum. Well‐developed muscle layers are found near the rectum and genital chamber. These results contribute to further studies on the ecology and biological control agents of Coleoptera and to provide a broad comparison of alimentary canal of Coleoptera species.     

Posterior regeneration following fission in the holothurian Cladolabes schmeltzii (Dendrochirotida: Holothuroidea)

The regeneration of the posterior portion of the body after fission was studied in the holothurian Cladolabes schmeltzii using electron microscopy methods. Following fission, the aquapharyngeal complex, gonad and anterior portion of the first descending part of the intestine remain in the anterior fragment of the body. The entire regeneration process is divided into five stages. In the first three stages, the digestive system and damaged ends of the longitudinal muscle bands regenerate. The intestine is formed through the rearrangement and growth of the remaining portion of the first descending part of the intestine. The gut anlage grows down the mesentery and joins the regenerating cloaca. The cloaca is formed from two sources: its posterior portion appears as a result of immersion of the epidermis, while the anterior portion develops from the terminal segment of the growing intestine. Regeneration of muscles progresses in the typical manner for echinoderms: through immersion and myogenic transformation of the coelomic epithelium. Respiratory trees appear in animals when the growth of the external part of the body has begun (fourth stage). They are formed as an outgrowth of the dorsal wall of the anterior portion of the cloaca. It was concluded that regeneration of the posterior portion of the body in the holothurian C. schmeltzii following fission is realized through morphallactic rearrangements of the remaining parts of organs. The main mechanism through which the digestive, respiratory, and contractile systems are formed is epithelial morphogenesis. Microsc. Res. Tech. 78:540–552, 2015. © 2015 Wiley Periodicals, Inc.     

Morphology of immature stages of Megaselia spiracularis Schmitz (Diptera: Phoridae)

In addition to causing myiasis in humans, Megaselia spiracularis Schmitz has also been reported as a forensically important fly. In this study, we presented the morphology of all larval instars and puparium of M. spiracularis using scanning electron microscopy. The first instar larva was composed of 12 segments. Antennae and maxillary palp complex were visible. Two spiracular slits could be seen at the posterior spiracle. The branch of posterior spiracular hairs was approximately equal to the palm‐formed base in length. Second and third larval instars were very similar to first instar, except for the presence of anterior spiracle. The labium of the second instar larva was triangular and ventrally curved, whereas it was a bilobed structure and the tip forked in the first instar. The bubble membrance comprised of ≈40 globules presented at the third instar larvae. Puparia showed a retracted cephalic region and a pair of pupal respiratory horns on the dorsum. A comparison of the morphological features between immature stages of M. spiracularis and M. scalaris, a forensically important fly indoors in Germany, Malaysia, and China, was discussed. Microsc. Res. Tech. 75:1297–1303, 2012. © 2012 Wiley Periodicals, Inc.     

Morphological description of the immature stages of Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae)

In the dipteran genus Hermetia, only 6 of the 78 valid species have documented immature stages: H. albitarsis Fabricius, 1805, H. aurata Bellardi, 1859, H. concinna Williston, 1900, H. illucens (Linnaeus, 1758), H. panamensis Greene, 1940 and H. pulchra Weidemann, 1830. In particular, H. illucens stands out due to its reported applicability for forensic, medical and economic purposes. Here, we described the morphology of eggs and immature stages of this species, with a view to detecting differences between instars and in the pupal stage, which should eventually help properly identifying larval age. We utilized both optical and scanning electron microscopy tools. The eggs are elliptical and elongated, and color varies from cream white to yellowish. The larvae are apodal, hemichephalic and holopneustic, flattened dorso‐ventrally and may be recognized by the head elongated, dorsal and ventral chaetotaxy of the cephalic capsule, thoracic and abdominal segments, and the morphology of the anterior and posterior spiracles. The pupae are adecticous and coarctate, tegument dark brown and pruinescence varying from brown to golden. The overall morphology across instars is similar, but marked variations were observed in the shape of the antennal articuli and the shape of the setae (first instar compared to the others). Our results supplement the biological information on Hermetia illucens and should aid the proper identification and aging of juveniles in the field, as a way to minimize errors in the calculation of the post‐mortem interval.     

Development beyond the gastrula stage and digestive organogenesis in the apple-snail <i>Pomacea canaliculata</i> (Architaenioglossa,Ampullariidae)

Development of Pomacea canaliculata from the gastrula stage until the first day after hatching is described. Trochophore embryos are developed after gastrulation, showing the prototroch as a crown of ciliated orange-brownish cells. However, no true veliger embryos are formed, since the prototroch does not fully develop into a velum. Afterward, the connection between the fore- and midgut is permeated and the midgut becomes full of the pink-reddish albumen, which is stored into a central archenteron’s lake, from where it is accumulated into the large cells forming the midgut wall (“giant cells”). Electron microscopy of giant cells in late embryos showed that albumen is engulfed by large endocytic vesicles formed between the irregular microvilli at the top of these cells. By the end of intracapsular development, giant cells become gradually replaced by two new epithelial cell types which are similar to those found in the adult midgut gland: the pre-columnar and the pre-pyramidal cells. Pre-columnar cells have inconspicuous basal nuclei and are crowned by stereocilia, between which small endocytic vesicles are formed. Pre-pyramidal cells have large nuclei with 2-3 nucleoli and show a striking development of the rough endoplasmic reticulum. The genesis of the three cell lineages (giant, pre-columnar and pre-pyramidal cells) is hypothetically attributed to epithelial streaks that occur at both sides of the midgut since early stages of development.     

Preservation, development, and hatching of resting eggs in the freshwater rotifer Brachionus calyciflorus pallas

The resting eggs of Brachionus calyciflorus produced under laboratory by manipulating various environmental conditions were subjected to preservation for long-term storage. Preservation strategies included as storing freshly collected resting eggs, dry resting eggs, and storing at 4°C. Results showed that the resting eggs preserved by drying as they were able to maintain the viability without much variation in the hatchability. The scanning electron micrographs clearly depicted the surface damage as well as change in the shape and surface topography due to the storage. The resting eggs thus stored were traced for their normal embryonic development, during which as many as 11 stages were traced and time taken for each stage of development was observed. Microscopic observations revealed that the first four stages represented the development of embryo and thereafter around 16-18 h extrution of neonate from egg occurred. At 18-19 h of development the characteristic of anterior and posterior spines appeared in the neonate. Just released neonate, after 4-5 h of development reached adult stage. Overall the hatching and embryonic development of the resting eggs preserved by "drying" were normal and hence this method could be adopted for long-term storage.     

Anterior regeneration after fission in the holothurian Cladolabes schmeltzii (Dendrochirotida: Holothuroidea)

The regeneration of the anterior portion of the body after fission was studied in the holothurian Cladolabes schmeltzii using electron microscopy methods. Following fission, the posterior portion of the digestive tube, cloaca, and respiratory trees remain in the posterior fragment of the body. The regeneration comprises five stages. In the first stage, connective‐tissue thickening (an anlage of the aquapharyngeal bulb) occurs on the anterior end between the torn‐off ends of the ambulacra. Most of the lost anterior organs developed in the second and third stages. The structures of water‐vascular system and nerve ring form through dedifferentiation, proliferation, and migration of cells of the radial water‐vascular canals and the radial nerve cords, correspondently. The lost digestive system portion is restored through the formation and merging of two anlagen. The digestive epithelium of the esophagus and pharynx develops from lining cells of microcavities near the central portion of the connective‐tissue thickening, which probably migrate from the epidermis. The second gut anlage develops through transformation of the anterior gut remnant portion. The enterocytes partly dedifferentiate, but the epithelium retains integrity. The gut anlage grows down the mesentery and joins the regenerating aquapharyngeal bulb. In the fourth and fifth stages, all lost organs are formed and have nearly normal structure. The regeneration was concluded to occur through morphallactic rearrangements of the remaining parts of organs. Epithelial morphogenesis is the key development mechanism of the digestive, water‐vascular, and nervous systems.     

A morphological analysis of the transition between the embryonic primitive intestine and yolk sac in bovine embryos and fetuses

The yolk sac (YS) is the main source of embryonic nutrition during the period when the placenta has not yet formed. It is also responsible for hematopoiesis because the blood cells develop from it as part of the primitive embryonic circulation. The objective of this study was to characterize the transitional area between the YS and primitive gut using the techniques of light microscopy, transmission electron microscopy, and immunohistochemistry to detect populations of pluripotent cells by labeling with Oct4 antibody. In all investigated embryos, serial sections were made to permit the identification of this small, restricted area. We identified the YS connection with the primitive intestine and found that it is composed of many blood islands, which correspond to the vessels covered by vitelline and mesenchymal cells. We identified large numbers of hemangioblasts inside the vessels. The mesenchymal layer was thin and composed of elongated cells, and the vitelline endodermal membrane was composed of large, mono‐ or binucleated cells. The epithelium of the primitive intestine comprised stratified columnar cells and undifferentiated mesenchymal cells. The transitional area between the YS and the primitive intestine was very thin and composed of cells with irregular shapes, which formed a delicate lumen containing hemangioblasts. In the mesenchyme of the transitional area, there were a considerable number of small vessels containing hemangioblasts. Using Oct4 as a primary antibody, we identified positive cells in the metanephros, primordial gonad, and hepatic parenchyma as well as in YS cells, suggesting that these regions contain populations of pluripotent cells. Microsc. Res. Tech. 76:756–766, 2013. © 2013 Wiley Periodicals, Inc.     

Cytotoxic effects of thiamethoxam in the midgut and malpighian tubules of Africanized Apis mellifera (Hymenoptera: Apidae)

Due to its expansion, agriculture has become increasingly dependent on the use of pesticides. However, the indiscriminate use of insecticides has had additional effects on the environment. These products have a broad spectrum of action, and therefore the insecticide affects not only the pests but also non‐target insects such as bees, which are important pollinators of agricultural crops and natural environments. Among the most used pesticides, the neonicotinoids are particularly harmful. One of the neonicotinoids of specific concern is thiamethoxam, which is used on a wide variety of crops and is toxic to bees. Thus, this study aimed to analyze the effects of this insecticide in the midgut and Malpighian tubule cells of Africanized Apis mellifera. Newly emerged workers were exposed until 8 days to a diet containing a sublethal dose of thiamethoxam equal to 1/10 of LC₅₀ (0.0428 ng a.i./l L of diet). The bees were dissected and the organs were processed for transmission electron microscopy. The results showed that thiamethoxam is cytotoxic to midgut and Malpighian tubules. In the midgut, the damage was more evident in bees exposed to the insecticide on the first day. On the eighth day, the cells were ultrastructurally intact suggesting a recovery of this organ. The Malpighian tubules showed pronounced alterations on the eighth day of exposure of bees to the insecticide. This study demonstrates that the continuous exposure to a sublethal dose of thiamethoxam can impair organs that are used during the metabolism of the insecticide. Microsc. Res. Tech. 77:274–281, 2014. © 2014 Wiley Periodicals, Inc.     

Development of histamine-immunoreactivity in the Central nervous system of the two locust species Schistocerca gregaria and Locusta migratoria

Locusts are attractive model preparations for cellular investigations of neurodevelopment. In this study, we investigate the immunocytochemical localization of histamine in the developing ventral nerve cord of two locust species, Schistocerca gregaria and Locusta migratoria. Histamine is the fast neurotransmitter of photoreceptor neurons in the compound eye of insects, but it is also synthesized in interneurons of the central nervous system. In the locust ventral nerve cord, the pattern of histamine-immunoreactive neurons follows a relatively simple bauplan. The histaminergic system comprises a set of single, ascending projection neurons that are segmentally arranged in almost every neuromere. The neurons send out their axons anteriorly, forming branches and varicosities throughout the adjacent ganglia. In the suboesophageal ganglion, the cell bodies lie in a posteriolateral position. The prothoracic ganglion lacks histaminergic neurons. In the posterior ganglia of the ventral nerve cord, the somata of the histaminergic neurons are ventromedially positioned. Histamine-immunoreactivity starts around 50% of embryonic development in interneurons of the brain. Subsequently, the neurons of the more posterior ganglia of the ventral nerve cord become immunoreactive. From 60% embryonic development, the pattern of soma staining in the nerve cord appears mature. Around 65% of embryonic development, the photoreceptor cells show histamine-immunoreactivity. The histaminergic innervation of the neuropile develops from the central branches toward the periphery of the ganglia and is completed right before hatching.     

Oral biofilm formation on the titanium and zirconia substrates

OBJECTIVE: The aim of this randomized crossover investigation was to assess the biofilm formation on two titanium and one zirconia substrates in relation to the topography and surface roughness of the materials. METHODS: Twenty‐four discs specimens for each evaluated material (Machined pure titanium, Cast pure titanium, or Zirconia) were evaluated after oral cavity exposure in six healthy subjects. The study was conducted in 3 phases according to the material evaluated. Each subject was asked to use a removable splint containing 4 disks of the same tested substrate, 2 located in the anterior, and 2 in the posterior region. Participants were asked to use the intraoral splint during 24 h. The total biofilm covering on the discs was evaluated by 1% of neutral red staining. EMV and surface roughness was carried out to correlate with the biofilm found between different substrates. RESULTS: Data showed higher mean roughness values for zirconia (Zc) when compared with titanium specimens (MPT and CPT; P < 0.001). MPT and CPT presented no differences between them (P > 0.05). The mean percentage (%) of covering biofilm on substrates was 84.14 for MPT, 86.22 for CPT and 90.90 for Zc. CONCLUSION: There were no significant differences in the total area of formed biofilm among the tested groups. No correlation was found between surface roughness and the total amount of formed biofilm in the groups. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

Ultramorphological characteristics of immature stages of Chrysomya albiceps (Wiedemann 1819) (Diptera: Calliphoridae), a fly specie of forensic importance

Forensic entomology is an area of science that serves as a tool in crime scene investigations. Usually, flies are the first insects to reach a dead body and can oviposit just a few hours after arrival. Therefore the knowledge of immature stages is essential for correct identification of the species found on corpses. Scanning electron microscopy gives detailed information about morphological characters helping to identify the immature forms and consequently serves as a tool in crime scene investigations. C. albiceps is a very important fly for forensic entomologists because its larvae are almost always present on a dead body and it is facultative predators and therefore can alter the composition of species present at the carcass. The aim of this study is to identify eggs, larvae, and puparia of C. albiceps using SEM. Eggs were elongated with the anterior region ending in a “Y” shape and the posterior end was tapered. The micropyle was a well‐adorned orifice with some projections around it. The first instar larva was composed of 12 segments separated by spines. Only one spiracular opening could be seen at the posterior spiracle. Body tegument was smooth and tubercles were not seen. Antennae and maxillary palps were visible. Second and third larval instars were very similar to first instar, except for the presence of anterior spiracle. However, body tegument was composed of net‐like patches and tubercles were visible. Tubercles present at the third instar larvae were robust and erect. Puparia showed a retracted cephalic region and curved tubercles. Microsc. Res. Tech. 73:779–784, 2010. © 2010 Wiley‐Liss, Inc.     

Structural and ultrastructural features of the Malpighian tubules of Dolycoris baccarum (Linnaeus 1758), (Heteroptera: Pentatomidae)

The morphology and ultrastructure of the Malpighian tubules of Dolycoris baccarum were analyzed by scanning (SEM) and transmission (TEM) electron microscopy in order to determine their functional organization. The Malpighian tubules are compared with similar structures of other insects based on cell structure and functional organization. The Malpighian tubules of D. baccarum extend from the midgut–hindgut region of the digestive tract. The Malpighian tubules are divided into two regions: the proximal segment is short and flattened and the distal segment is long, stringy in shape and free in hemolymph. The tubules are generally long and narrow. There is a large number of trachea around the tubules. They consist of a single layer of epithelial cells. It is observed in the TEM observation that the epithelial cells have numerous microvilli at the apical side of the cells. At the basal side of the cells, there is a great number of membrane foldings and mitochondria among them. Besides some spherites, mitochondria, lysosome‐like bodies, and large or small granules can be distinguished in the cells. With this study, we aimed to demonstrate the ultrastructure of the Malpighian tubules of D. baccarum and differences or similarities with other species.     

Embryonic development of endoderm in chicken (Gallus gallus domesticus)

The poultry industry is a sector of agribusiness which represents an important role in the country's agricultural exports. Therefore, the study about embryogenesis of the domestic chicken (Gallus gallus domesticus) has a great economic importance. The aim of this study was to evaluate embryonic development of the endoderm in chicken (Gallus gallus domesticus). Forty fertilized eggs of domestic chickens, starting from the 1st day of gestation and so on until the 19 days of the incubation were collected from the Granja São José (Amparo, SP, Brazil). Embryos and fetus were fixed in 10% formaldehyde solution, identified, weighed, measured, and subjected to light and scanning electron microscopy. The endoderm originates the internal lining epithelium of the digestive, immune, respiratory systems, and the organs can be visualized from the second day (48 h) when the liver is formed. The formation of the digestive system was complete in the 12th day. Respiratory system organs begin at the fourth day as a disorganized tissue and undifferentiated. Their complete differentiation was observed at the 10 days of incubation, however, until the 19 days the syrinx was not observed. The formation of immune system at 10th day was observed with observation of the spleen, thymus, and cloacal bursa. The study of the organogenesis of the chicken based on germ layers is very complex and underexplored, and the study of chicken embryology is very important due the economic importance and growth of the use of this animal model studies such as genetic studies. Microsc. Res. Tech. 76:803–810, 2013. © 2013 Wiley Periodicals, Inc.     

Fluorescence microscopy study on the cytoskeletal displacements during sperm differentiation in the bush‐cricket Tylopsis liliifolia (Fabricius) (Orthoptera: Tettigoniidae)

A study by fluorescence microscopy has been carried out on male gametes from testicular follicles, seminal vesicles, spermatophores, and seminal receptacles of the bush‐cricket Tylopsis liliifolia, focusing the attention on localization and movements of F‐actin and α‐tubulin during sperm differentiation, since data in this respect are lacking in the Orthoptera. F‐actin and α‐tubulin positivity was detected in the testicular follicles, in particular at the bridges connecting spermatids of a same clone and around their nucleus, during the first differentiation stages. During the following differentiation stages in the testes, F‐actin was found at one of the spermatid poles and then, during nucleus elongation, at the whole acrosomal region. A peculiar F‐actin‐positivity was found at the flagellum, more markedly immediately posterior to the nucleus, at the basal body region of the gametes from the testicular follicles and from the other examined districts. Other interesting data from our investigations concerns the α‐tubulin displacements during the differentiation stages of the spermatid and a constant absence of α‐tubulin‐positivity where the centrioles are located. No positivity was also found for both α‐tubulin and nuclear markers at the anterior region of the gamete, where the acrosomal wings are localized. Our results, compared with what is so far known in literature for the insects, lead us to assert that microfilaments and microtubules undergo gradual displacements, markedly in the testicular follicles, during the morphogenesis of the male gamete of T. liliifolia aimed to its organization and motility and probably also to its interaction with the female gamete. Microsc. Res. Tech. 79:81–88, 2016. © 2015 Wiley Periodicals, Inc.     

Cornea and its adaptation to environment and accommodation function in veiled chameleon (Chamaeleo calyptratus): ultrastructure and 3D transmission electron tomography

We investigate the ultrastructural features and 3D electron tomography of chameleon (Chamaeleon calyptratus) which is a native of desert environments of Saudi Arabia. The corneas of the chameleon were fixed in 2.5% glutaraldehyde containing cuprolinic blue in sodium acetate buffer for electron microscopy and tomography, and observed under a JEOL 1400 transmission electron microscope. The thin cornea (21.92 μm) contained 28–30 collagen fibril lamellae. The middle stromal lamellae (from 13 to 19) contained keratocytes with a long cell process and filled with granular material. The CF diameter increased from lamella 1 (30.44 ± 1.03) to Lamella 5 (52.83 ± 2.00) then decreased towards the posterior stoma. The percentage of large CF diameters (55–65 nm) was very high in the lamellae L14 (38.8%) and L15 (85.7%). The mean PGs area of the posterior stroma (448.21 ± 24.84 nm²) was significantly larger than the mean PGs area of the anterior, (309.86 ± 8.2 nm²) and middle stroma 245.94 ± 8.28 nm²). 3D electron tomography showed the distribution of PGs around and over the CF. Variable diameters of CFs in the anterior stroma may provide compact lamellae which may restrict the low wavelength of light. Variable diameters of CFs in the anterior stroma may provide compact lamellae which may restrict the low wavelength of light. This accommodation function is achieved by bending of the cornea. During bending the anterior stroma was stretched and the posterior stroma was compressed due to the presence of small CFs. The middle stroma remained stiff due to the presence of large CFs. Large proteoglycans not only maintain hydration for a longer period of time, but also act as a lubricant to neutralise the shear forces in the anterior and posterior stroma during bending.     

Spherites in the midgut epithelial cells of the sugarcane borer parasitized by Cotesia flavipes

Diatraea saccharalis, the main pest of sugarcane, has been controlled by Cotesia flavipes. Very little is known about the effect of parasitism on the host organs, including the midgut. The Lepidoptera midgut epithelium is composed of columnar, goblet, regenerative, and endocrine cells. Spherites have been described in columnar and regenerative cells of several Lepidoptera species, and presented a lot of functional meaning. We identified spherites in the midgut epithelial cells of non-parasitized D. saccharalis larvae analyzed the effect of parasitism on spherite morphology and distribution along the length of the midgut. Midgut fragments of both non-parasitized and parasitized larvae were processed for transmission electron microscopy. All the midgut epithelial cells showed spherites, but they were not preferentially located in a particular part of the cells. Parasitized larvae had more spherites, mainly in the columnar cells, than non-parasitized larvae. This observation was associated with an ionic imbalance within the insect host. Spherites were more abundant in the anterior midgut region than in other regions, which suggests that this region is involved in ion transport by intracellular and/or paracellular route. The morphological variability of spherites in the cells of parasitized larvae was related to the developmental stages of these structures.     

Distribution of FMRFamide-like immunoreactivity in the alimentary tract and hindgut ganglia of the barnacle Balanus amphitrite (Cirripedia, Crustacea)

In this study, the presence and distribution of FMRFamide-like immunoreactivity in the alimentary tract of barnacle Balanus amphitrite were investigated. A net of nerve fibers strongly immunoreactive to FMRFamide-like molecules was localized in the posterior midgut and hindgut. Positive varicose nerve terminals were also localized close to the circular muscle cells and, in the hindgut, close to the radial muscular fibers. Besides this nerve fibers network, one pair of contralateral ganglia was localized in the hindgut, each of them constituted by two strongly FMRFamide-labeled neurons and one nonlabeled neuron. Their immunoreactive axons directed toward the hindgut and posterior midgut suggest an involvement of FMRFamide-like substances in adult B. amphitrite gut motility. The hindgut associated ganglia of barnacles seem to correspond to the terminal abdominal ganglia of the other crustaceans. Since they are the only residual gut ganglia in the barnacle's reduced nervous system, we can hypothesize that gut motility needs a nervous system regulation partially independent of the central nervous system.     

Morphology of immature stages of Dohrniphora cornuta (Bigot) (Diptera: Phoridae)

Morphology of all larval instars and puparium of Dohrniphora cornuta (Bigot), a most common phorid fly species indoors in China, is presented using scanning electron microscopy. The first instar larva was composed of 12 segments, each of segments 3–11 with six slender tubercles situated dorsally, dorsolaterally, and laterally in transverse row. These tubercles divided into two segments, of which the basal one was smooth, and the brush‐shaped distal one was comprised of a cluster of fine spines. Antennae and maxillary palp complex were visible. Two slits could be seen at the posterior spiracle. Besides the presence of anterior spiracle, the tubercles of second instar became stouter than those of first instar and were covered by numerous long bristles from the base to top. The posterior spiracle contained four slits. Third larval instar was similar to second instar. The bubble membrane comprised of ≈120 globules with a pointed tip on their top presented at the segment 5 of third instar larvae. Puparia showed a retracted cephalic region and a pair of distinct pupal respiratory horns on the dorsum. The respiratory horns were long and bore numerous branches from base to apex. The apex of branch with two longitudinal slits was relatively broad and curled dorsally. Microsc. Res. Tech. © 2012 Wiley Periodicals, Inc.     

Three-dimensional reconstruction of the remodeling of the systemic vasculature in early pig embryos

Current research on angiogenesis and vascular regression is mainly focused on pathological conditions such as tumor growth and diabetic retinopathy, while a suitable physiological model to study the controlling factors in these processes is still lacking. The remodeling pattern of the embryonic vasculature into the adult configuration, such as the branchial arch arterial system developing into the aorta or the early embryonic veins building the caudal vena cava can potentially serve as a model. However, practical applications of the embryonic vascular patterning are impeded by the current controversy over the exact development of the caudal vena cava in mammals. To elucidate these ambiguities, specific developmental stages of vascular development in pig embryos were mapped by means of computer-assisted 3D reconstructions starting from histological serial sections of Bouin's fixed embryos. Special attention was given to venous segments in the lumbar region, as their origin and fate are equivocally described in literature. Here we demonstrate that these venous segments originate from the caudal cardinal veins which are forced to migrate during development into a more dorsal position due to the expansion of the developing metanephroi and the more dorsal relocation of the umbilical arteries. These findings are in contrast with the generally accepted theory that the venous segments in the lumbar region arise from newly formed veins that are located dorsal to the early caudal cardinal system.