Gills of the medaka (Oryzias latipes): A scanning electron microscopy study

The general morphology and surface ultrastructure of the gills of adult and larvae medaka (Oryzias latipes) were studied in freshwater and seawater using scanning electron microscopy. The gills of all examined fish were structurally similar to those of other teleosts and consisted of four pairs of arches supporting (i) filaments bearing lamellae and (ii) rakers containing taste buds. Three cell types, specifically pavement cells, mitochondria‐rich cells (MRCs), and mucous cells, constituted the surface layer of the gill epithelium. Several distinctive characteristics of medaka gills were noted, including the presence of regularly distributed outgrowth on the lamellae, enlarged filament tips, the absence of microridges in most pavement cells in the filament and lamellae and the presence of MRCs in the arch at the filament base. A rapid mode of development was recorded in the gills of larval fish. At hatching, the larvae already had four arches with rudimentary filaments, rakers, and taste buds. The rudimentary lamellae appeared within 2 days after hatching. These results suggest the early involvement of larval gills in respiratory and osmoregulation activities. The responses of the macrostructures and microstructures of gills to seawater acclimation were similar in larvae and adult fish and included modification of the apical surface of MRCs, confirming the importance of these cells in osmoregulation. The potential roles of these peculiarities of the macrostructures and microstructures of medaka gills in the major functions of this organ, such as respiration and osmoregulation, are discussed.     

The crater defect in boar spermatozoa: A correlative study with transmission electron microscopy,scanning electron microscopy,and light microscopy

Nuclear vacuoles resembling the “crater defect” described in bull spermatozoa were observed in 14 boars. Both the incidence of the defect and semen quality were monitored with phase contrast microscopy over a three-month period. The percentages of cratered spermatozoa varied widely both among boars and in ejaculates from the same boar taken on different days. The presence of cratered spermatozoa at a level of 5% or more appeared to be associated with low semen quality. The defect was studied with scanning and transmission electron microscopy and was found to consist of nuclear invaginations, about 0.5 μm in diameter, containing some scanty amorphous electron-dense material. In boars showing a high incidence of spermatozoa with crater defects, abnormalities of the acrosome and perforatorium were common.     

Antifungal activity of allylamines on Epidermophyton floccosum: scanning electron microscopy study

The action of allylamine antifungal agents on Epidermophyton floccosum was studied using scanning electron microscopy. After 7 days of culture on Sabouraud dextrose agar, Epidermophyton floccosum samples were brought in contact with concentrations of 0.2 and 2 g ml^–1 and 0.01 and 0.1 g ml^–1 of naftifine and terbinafine, respectively. Lesions observed after 24 h, 3 and 7 days of contact were mainly on the structure and rigidity of the mycelial and macroconidial wall. They were characterized by hyphal ballooning and twisting and by apical bulbous bulges. Deterioration of macroconidia was characterized by wall exfoliation. The intensity of the deterioration depended on the dose and only slightly on the length of time that the sample and the antifungal drug were in contact.     

The rat pituitary cleft: A correlated study by scanning and transmission electron microscopy

Summary SEM reveals that the inner surface of the pituitary cleft is lined by a continuous layer of marginal cells possessing microvillous and ciliated apical surfaces. The ciliated cells are more numerous on the posterior side (toward the pars intermedia) than on the anterior side of the cleft (toward the pars distalis). In contrast small infoldings (crypts) were occasionally noted only on the marginal layer covering the distal part of the hypophysis. In some areas of the cleft the surface features of the marginal cells are rather similar to the epithelial cells populating the upper parts of the respiratory tract in their topography and distribution. In other regions they also show striking similarities with the ependymal cells (tanycytes) lining the lateral recesses of the 3rd ventricle and the infundibular process with which the pituitary cleft has a very close topographical relationship.The parenchymal cells of the pars distalis are closely related to the flattened marginal cells of the cleft. The intercellular spaces of the pars distalis form a three-dimensional labyrinthic series of cavities continuous with the submarginal spaces of the cleft. Further SEM and TEM results demonstrate that the majority of the microvillous marginal cells lining both sides of the cleft possess surface features such as bulbous protrusions, laminar evaginations and large cytoplasmatic vacuoles, which are very likely the expression of an active transport of fluids.On the basis of these results it is concluded that the fluid-like material (colloid) present in the pituitary cleft is mainly derived from the fluids contained in the lacunar spaces of the pars distalis. Thus, marginal cells by absorbing fluids from the cleft by active endocytosis, may transport to the pars intermedia material (or hormones) produced in the distal part of the gland and vice versa.The cilia present on many marginal cells, based on their 9+2 tubular pattern, possess a kynetic role. This is very similar to that shown by the ciliated cells of the ependyma lining the brain ventricles. The occurrence of ciliated cells within the pituitary parenchyma (mainly in the follicles) suggests that they probably arise from the ciliated cells populating the marginal layer of the cleft and with which the parenchyma cells are closely related.     

Renal microvasculature in the adult pipid frog,Xenopus laevis: A scanning electron microscope study of vascular corrosion casts

We studied the opisthonephric (mesonephric) kidneys of adult male and female Xenopus laevis using scanning electron microscopy (SEM) of vascular corrosion casts and light microscopy of paraplast embedded tissue sections. Both techniques displayed glomeruli from ventral to mid-dorsal regions of the kidneys with single glomeruli located dorsally close beneath the renal capsule. Glomeruli in general were fed by a single afferent arteriole and drained via a single thinner efferent arteriole into peritubular vessels. Light microscopy and SEM of vascular corrosion casts revealed sphincters at the origins of afferent arterioles, which arose closely, spaced from their parent renal arteries. The second source of renal blood supply via renal portal veins varied interindividually in branching patterns with vessels showing up to five branching orders before they became peritubular vessels. Main trunks and their first- and second-order branches revealed clear longish endothelial cell nuclei imprint patterns oriented parallel to the vessels longitudinal axis, a pattern characteristic for arteries. Peritubular vessels had irregular contours and were never seen as clear cylindrical structures. They ran rather parallel, anastomosed with neighbors and changed into renal venules and veins, which finally emptied into the ventrally located posterior caval vein. A third source of blood supply of the peritubular vessels by straight terminal portions of renal arteries (vasa recta) was not found.     

Light microscopy and scanning electron microscopy studies on the reduction of the tongue microstructures in the white stork (Ciconia ciconia,Aves)

The structure of the tongue in the white stork (Ciconia ciconia) is observed macroscopically and under light and scanning electron microscopy. Our observations of the tongue reveal a rare terminal reduction of the size of the tongue and microstructures of the lingual mucosa among the investigations of birds published so far. The short, triangular tongue with a pointed tip is approximately 2.5 cm long in the adult and is situated in the caudal part of the oral cavity close to the laryngeal prominence. On the dorsal surface of the tongue, no typical mucosa microstructures like lingual papillae, median groove or lingual prominence are observed. The main structure of the tongue is composed of rostral part of hyoid apparatus, that is, entoglossal cartilage connects with basihyoid. Very thin mucosa is composed of fibrous connective tissue covered with orthokeratinized epithelium. No lingual glands and muscles are observed in the lamina propria of mucosa. Even though the triangular shape of the tongue in the white stork is typical for birds, the inner structure of the reduced organ is composed only of flat cartilagineous entoglossum of hyoid apparatus. During feeding behaviour of the white stork, the food transportation in oral cavity called cranio‐inertial transport is undoubtedly affected by structural reduction of the tongue.     

Microvascular anatomy of testes in the adult pipid frog,Xenopus laevis Daudin: A scanning electron microscopic study of vascular corrosion casts

The three-dimensional microvascular anatomy of the testes of adult Xenopus laevis was studied by scanning electron microscopy of vascular corrosion casts. Results showed that testicular arteries branch off from urogenital arteries and approach the testes via the mesorchium. At the dorsal surface of testes, arteries course towards the medial and lateral surfaces of the ovoid testes, pierce the tunica albuginea and run in the subalbugineal space and then penetrate the testicular parenchyma. In the parenchyma, they branch in all directions. At sites where larger branches arise, sphincters are present. Intimal cushions are found at the origin of smaller branches. Terminal arterioles capillarize and form a wide-meshed capillary network around convoluted seminiferous tubules. Inter- and peritubular capillaries cannot be differentiated reliably. Arterio-venous transition distances are short. Arterio-arterial anastomoses and veno-venous anastomoses are present. Testicular venules empty into a venous subalbugineal plexus which shows veno-venous anastomoses of different lengths and calibres. Signs of the ongoing non-sprouting angiogenesis, particularly intussusceptive branch remodelling, reflect the dynamics of the testicular parenchyma. The present study is the first that demonstrates the testicular microvascular anatomy in an anuran species and shows that X. laevis and men share the intricate convoluted seminiferous tubules with associated vascular patterns as a feature in common.     

激光共聚焦扫描显微镜和透射电镜观察大鼠纹状体内谷氨酸能突触连接的对比观察

目的 探讨使用激光共聚焦扫描显微镜 (Laser scanning confocal microscope,LSCM)观察大鼠纹状体内谷氨酸能突触连接的方法的可行性.方法 12只正常大鼠分为两组,6只大鼠进行纹状体中等棘刺神经元的CM-DiI 单细胞标记,然后Ⅰ型囊泡膜谷氨酸转运体(vesicular glutamate transporter 1,VGluT1 )免疫荧光标记,LSCM层扫后三维重建,观察VGluT1阳性位点在中等棘刺神经元树突上的分布.另外6只大鼠用TEM观察不对称性突触在纹状体神经元树突上的分布.对两种方法的结果进行比较.结果 用LSCM 和TEM方法观察到的纹状体神经元上谷氨酸能突触连接分布情况一致,没有统计学差异.但LSCM更具优越性的是,可以对图像进行三维重构,从而有利于对神经元之间突触连接的空间分布观察和定量分析.结论 神经细胞荧光标记技术结合LSCM观察是考察纹状体神经元上谷氨酸能突触连接的有效方法.     

The digestive tract of the amberjack Seriola dumerili, Risso: a light and scanning electron microscope study

The histology of the digestive tract of the amberjack ( Seriola dumerili , Risso) was studied using light and scanning electron microscopy. The anterior oesophagus mucosa displays primary and secondary folds lined with a stratified squamous epithelium with fingerprint-like microridges which is substituted, on the top of the oesogaster folds, by a simple columnar epithelium with short microvilli. Only primary folds are present in the stomach. The anterior portion is rich in simple tubular glands, whereas the oesogaster and the pyloric region are devoid of them. Pyloric caeca and anterior and middle intestine mucosa display the same pattern of folding. The dominant cell type is the enterocyte, which exhibits larger and thinner microvilli in the caeca than in the intestine. The columnar epithelium of the rectum is replaced, in the anal sphincter, by a stratified flattened epithelium. Goblet cells are numerous throughout the whole length of the tract with the exception of the initial part of the oesophagus, the oesogaster, the stomach and the anal sphincter. Mucosubstances have been shown to vary in the different regions of the gut: acid mucines are found in the oesophagus, pyloric stomach, caeca, intestine and rectum, whereas neutral mucosubstances dominate in the anterior portion of the stomach. The muscularis is well developed throughout the length of the tract: two layers of striated muscle at the oesophageal level; two layers of smooth muscle in the stomach wall and three at the intestinal level.     

Relationship between the length of sperm preincubation and zona penetration in the golden hamster: A scanning electron microscopy study

Hamster spermatozoa are able to fertilize a high percentage of zona-intact hamster oocytes when they are preincubated for 2 hr in a chemically defined medium. From this time on, the longer the preincubation time the lower the percentage penetration. Spermatozoa preincubated for 6 or more hr are unable to cross the zona pellucida, retaining however their ability to fuse with zona-free hamster oocytes. Zona-intact hamster oocytes, as described above, were observed with the scanning electron microscope. When the oocytes were inseminated with spermatozoa preincubated for 1 to 5 hr the outer surface of the zona showed the penetrating spermatozoa and the sperm tracks made by those that failed to cross it. With longer preincubation times no penetrating spermatozoa were observed, and very few sperm tracks were present on the outer surface of the zona. Control experiments showed that neither eggs, spermatozoa, nor fertilization were affected by the medium recovered after long preincubations. These results show that care should be taken regarding the preincubation time when using the in-vitro fertilization technique.     

External sense receptors in microdrile oligochaetes (Annelida,Clitellata) as revealed by scanning electron microscopy: Typology and patterns of distribution in the main taxonomic groups

This work summarizes the observations on 30 species of microdriles belonging to the families Naididae (Rhyacodrilinae, Pristininae, Naidinae, Phallodrilinae, and Tubificinae), Phreodrilidae, Lumbriculidae, and Enchytraeidae using scanning electron microscopy. The lumbricid Eiseniella tetraedra, a megadrile species common in typical microdrile habitats, was used for comparison. Microdriles display external ciliate sense structures along the entire body; even at the clitellum and in budding and regeneration zones. According to the shape of the cilia, these sense structures can be divided into receptors of blunt cilia, receptors of sharp cilia, and composed receptors. Sense receptors can be morphologically unconspicuous or clearly defined on sensory buds or papillae. All microdriles studied have receptors of blunt cilia. Enchytraeids have characteristic receptors of short cilia. Pristina (Pristininae), Chaetogaster, Ophidonais, and Stylaria (Naidinae) have receptors of long blunt cilia. Composed receptors were found only in some microdriles and E. tetraedra. Receptors of sharp cilia have been found in most microdriles. Enchytraeids might be the only exception, but sharp cilia are probably present in the amphibiotic Cognettia sphagnetorum. Sensory cells with long sharp cilia might play a rheoreceptor role, and their presence in E. tetraedra and C. sphagnetorum would imply the reappearing of an ancient character that was probably lost with the transit from aquatic to terrestrial habitats. Some lumbriculids have ciliated fields. Anatomically, these structures appear as intermediate between the typical isolate sensory structures of microdriles and the sensillae of the hirudineans. The general pattern in microdriles is that uniciliate receptors and multiciliate receptors are separated, which supports the presumed aquatic origin of the clitellates. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Lens fiber organization in four avian species: a scanning electron microscopic study

The three-dimensional organization of the eye lenses of the chicken, the canary, the song-thrush and the kestrel was studied using light and scanning electron microscopy. The lenses of birds are characterized by the presence of two distinct compartments: the annular pad and the main lens body, separated by a cavum lenticuli. The annular pad fibers had a hexagonal circumference all contained a round nucleus and except for the canary were smooth-surfaced and lacking anchoring devices. In the canary, however, the annular pad fibers were studded with edge protrusions and ball-and-socket junctions. The semicircular main lens body fibers of all four species were studded with ball-and-socket junctions and edge protrusions. In contrast with mammals these anchoring devices were present throughout the lens up to the embryonal nucleus. Superficially the main lens body fibers were extremely flat. Additionally membrane elevations and depressions and globular elements were found on these central fibers in three species, the kestrel being the exception. At the transition between annular pad and main lens body the fibers turned their course and the nuclei became oval and disappeared in the deeper aspect of the main lens body. The cavum lenticuli was filled with globules tied off from the annular pad fibers. It seems attractive to assume that the presence of a separated annular pad, a cavum lenticuli filled with globular elements, the extreme flatness of the superficial central fibers and the studding of these central fibers with anchoring devices up to the embryonal nucleus are morphological expressions of the mouldability of the bird's eye lenses and consequently would explain their efficient accommodative mechanism including formation of a lenticonus. The presence of nuclei in the annular pad fibers and their typical change at the transitional zone between annular pad and main lens body are suggestive for a two-phased differentiation in bird's lens fibers: differentiation of the germinative epithelial cells to annular pad fibers which migrate to the main lens body after which they differentiate further to main lens body fibers.     

How cells settle on glass: A study by light and scanning electron microscopy of some properties of normal and stimulated macrophages

Summary Some properties of normal and stimulated peritoneal macrophages have been studied using light microscopy, cinemicroscopy, and scanning electron microscopy. No difference in the overall rate of translational movement was found between normal and stimulated cells. Macrophages were found to settle on glass by a process involving initial protrusion of very fine finger-like processes, followed by veils. Full extension occurred sooner in stimulated cells.We are grateful to Professor R. Barer for his criticisms, to Miss Anne Edwards for technical help, to Mr. G. Tuck for help with cinemicroscopy, and to the Science Research Council and the Medical Research Council for grants.     

Isolation,identification, and in vitro predatory activity of nematophagous fungus Arthrobotrys musiformis and its interaction with nematodes using scanning electron microscopy

We isolated and identified nematophagous fungus Arthrobotrys musiformis from materials derived from cattle and sheep. We also molecularly characterised the native fungal isolates and evaluated the nematophagous activity of the isolates. A total of 19 isolates of A. musiformis were isolated from 1532 samples, and the detection rate of A. musiformis in all samples was 1.24%. These isolates were identified using a light microscope and their 5.8S rDNA, 18S rDNA, 28S rDNA, and the internal transcribed spacers 1 and 2 region. Interaction of the isolate (NPS045) with the nematode targets of the infective larvae (L₃) of Haemonchus contortus and the free-living nematode Caenorhabditis elegans was observed by scanning electron microscopy (SEM). SEM result showed that the two species of nematodes were initially captured at 5?h after being added to the isolates. L₃ was penetrated at 22?h after capture and completely destroyed by the fungus at 68?h. C. elegans was penetrated at 14?h post-capture and was completely digested by the fungus at 24?h. In vitro experimental assay of samples in 24-well plates showed that for the three fungal isolates, the L₃s of Trichostrongylus colubriforms were reduced by 94.80%, 90.17%, and 89.02%.     

Visualization of the cytostome in Trypanosoma cruzi by high resolution field emission scanning electron microscopy using secondary and backscattered electron imaging

High resolution scanning electron microscopy was used to analyze the surface of epimastigote, amastigote and trypomastigote forms of Trypanosoma cruzi. Significant differences were observed between these forms and in different areas of the same cell. The cytostome found in amastigote and epimastigote forms could be easily visualized in images, which resemble those obtained only using the freeze-fracture technique. In contrast to other areas of the cell surface, the region of the cytostome, localized close to the flagellar pocket, showed a rugous surface and an opening with a diameter of 90 nm. Gold-labeled concanavalin A binds to the whole cell surface. However, the extent of binding was much higher in the region of the cytostome. The results obtained show that high resolution scanning electron microscopy is a powerful technique for analyzing the surface of protozoa.     

Organization of the olfactory system of the Indian major carp <Emphasis Type="Italic">Labeo rohita</Emphasis> (Ham.): A scanning and transmission electron microscopy study

Catla catla, Labeo rohita, and Cirrhinus mrigala represent important alimentary fish in India. Their reproduction/breeding depends on seasons. Fish perceive external factors-stimuli and chemical signals through the olfactory system that plays the key role in central regulation of reproduction. However, no electron microscopy data are available on organization of olfactory components of these fish. We studied organization of the olfactory organ in male L. rohita using scanning (SEM) and transmission electron microscopy (TEM). This organ consists of olfactory epithelium, a short nerve, and olfactory bulb. The olfactory organ is ovoid in shape and consists of about 47–52 lamellae in adults and about 14–20 lamellae in fingerlings. These lamellae originate from the midline raphe. By SEM, microvillar sensory and ciliated non-sensory cells were observed in the lamellae. TEM revealed microvillar receptor cell with rough endoplasmic reticulum and Golgi apparatus towards apical end. Basal cells were present at the base of receptor cell, supporting cells were located adjacent to the olfactory receptor neurons, while epithelial cells—in the nonsensory part of olfactory epithelium. Mast, blastema, and macrophage cells were also found at the basement membrane. This work is the first publication on ultrastructural organization of the olfactory system of the Indian major carp, which provides information about morphological and ultrastructural organization of the olfactory system and opens new avenues for further investigation of chemical neuroanatomy, sensory signal processing, and neural regulation of reproduction in the Indian major carp.     

A scanning electron microscopic study of germ cell maturation in the reproductive tract of the male soupfin shark (Galeorhinus galeus)

Germ cell maturation in the reproductive tract of the soupfin shark (Galeorhinus galeus) was studied using scanning electron microscopy (SEM). The SEM showed changes in Sertoli cytoplasm volume during spermatogenic development. In immature spermatocysts in the germinal zone, spermatogonia were embedded in Sertoli cytoplasm. In spermatogonial spermatocysts, Sertoli cells were adluminally located in the spermatocyst, with spermatogonia enveloped in the basal portions of the cytoplasm. During the round spermatid stage, Sertoli cytoplasm was very scanty. Spermatid elongation was accompanied by a progressive increase in the volume of Sertoli cytoplasm, notably around the spermatid heads. In the mature spermatocyst, bundles of spermatozoa are totally enveloped by Sertoli cytoplasm. Spermatozoa occurred randomly in the epididymis. However, in the ampulla ductus deferentis, spermatozoa reaggregated and were embedded in a mucoid substance to form highly ordered spherical bundles. In the sperm bundle, the spermatozoa heads were arranged such that the helical turns of adjacent spermatozoa were precisely aligned, and all the heads in the bundle formed a distinct apex. This study demonstrates the utility of exploring the relationship between germ cells and Sertoli cells in an evolutionarily ancient vertebrate, such as the shark.     

The ultrastructure of the lens of the cephalopod Sepiola: A scanning electron microscopic study

The ultrastructure of the eye lens of Sepiola atlantica was investigated using scanning electron microscopy. The main lens elements in both the anterior and posterior half of the Sepiola lens are plate-like configurations with fiber-like extensions at their margins. Anteriorly the plates are plano-convex, posteriorly subspherical. The central, primordial, posterior plates are spherical with no marginal extensions. The plates are mutually anchored by protrusions and invaginations and by push-button attachments. The posterior and anterior halves are separated by a septum which consists of concentric zones of radially orientated elongated cells. The marginal extensions of the plates and the septal elements are closely associated. The unique structure of the septum makes it a good candidate for the high resistance barrier between the posterior and anterior halves of the Sepiola lens (Jacob and Duncan, 1981).     

Adhesion of intermediate filaments and lipid droplets in adrenal cells studied by field emission scanning electron microscopy

High-resolution field emission scanning electron microscopy was used to study the organisation of intermediate filaments around lipid droplets and their binding to these droplets, in primary culture of bovine adrenal cells. Whole-mount preparations of intermediate filaments and bound lipid droplets were prepared from cells grown on Formvar-coated grids and processed by freeze-drying. Intermediate filaments were seen as an interconnected network enveloping the entire droplet. The bound filaments appear to be directly adherent to the surface of the droplet and hence take on its curved contour. The binding of the filaments to the droplets was determined by means of tilting. This study provides a new approach to investigate the cytoskeleton and its associated structures with high-resolution three-dimensional images.