Fine structure of the dorsal lingual epithelium of the Japanese monkey Macaca fuscata fuscata.

Filiform papillae, which were densely distributed all over the dorsal surface of the lingual body, were crown-shaped, with a central, circular area that sloped in the anterior direction and several branches that surrounded it in a semicircle from the back of the central area. Dome-shaped, fungiform papillae were scattered among these filiform papillae. At the posterior end of the lingual body, there were four circumvallate papillae. Prominent microridges and elevated intercellular borders were widely distributed in the central area of the filiform papillae and the interpapillar region. On the surface of the branches of the filiform papillae, microridges were rarely seen. On the surface of the fungiform papillae, indistinct microridges were observed. Histologically, the dorsal lingual epithelium revealed three different regions: the epithelium on the anterior side of the filiform papillae, the epithelium on the posterior side of the filiform papillae and the interpapillar epithelium. Whereas the basal and suprabasal cells are similar throughout, differences characterize the intermediate and surface layers. Keratohyalin granules appear predominantly in the intermediate layer in the epithelium on the anterior side of filiform papillae. In the epithelium on the posterior side of the filiform papillae, no keratohyalin granules occur and, instead, tonofibrils are prominent. The cells become significantly flattened. In the interpapillar epithelium, no keratohyalin granules are visible, and the tonofilaments occupy almost the entire cytoplasm of most cells in the intermediate and surface layers. The cells are larger in volume in these layers.     

Head sensory organs of Dactylopodola baltica (Macrodasyida, Gastrotricha): a combination of transmission electron microscopical and immunocytochemical techniques

The anterior and posterior head sensory organs of Dactylopodola baltica (Macrodasyida, Gastrotricha) were investigated by transmission electron microscopy (TEM). In addition, whole individuals were labeled with phalloidin to mark F-actin and with anti-alpha-tubulin antibodies to mark microtubuli and studied with confocal laser scanning microscopy. Immunocytochemistry reveals that the large number of ciliary processes in the anterior head sensory organ contain F-actin; no signal could be detected for alpha-tubulin. Labeling with anti-alpha-tubulin antibodies revealed that the anterior and posterior head sensory organs are innervated by a common stem of nerves from the lateral nerve cords just anterior of the dorsal brain commissure. TEM studies showed that the anterior head sensory organ is composed of one sheath cell and one sensory cell with a single branching cilium that possesses a basal inflated part and regularly arranged ciliary processes. Each ciliary process contains one central microtubule. The posterior head sensory organ consists of at least one pigmented sheath cell and several probably monociliary sensory cells. Each cilium branches into irregularly arranged ciliary processes. These characters are assumed to belong to the ground pattern of the Gastrotricha.     

Scanning-electron-microscopic study of the dorsal lingual surface of the squirrel monkey

The structure of the lingual papillae and the ultrastructure of the surface of the lingual dorsal epithelial cells of squirrel monkeys were observed by scanning electron microscopy. Filiform papillae were distributed over the entire dorsal surface of the tongue, except for the radix zone. Fungiform papillae were scattered among these filiform papillae. In the middle of the posterior end of the lingual body, a single vallate papilla was located. Higher magnification of the lingual dorsal epithelium revealed that prominent microridges and elevated intercellular borders occurred widely in the basofrontal area of the filiform papillae, interpapillar area and lingual radix zone. On the surface of the upper part of the filiform papillae, fine pits and hollows were observed. Indistinct microridges were distributed over the surface of the fungiform papillae.     

Fine structural study of keratinization of the filiform papillae in the tongue in humans]

The fine structure of the keratinization of the papilla filiformis of the human tongue was described for the first time; Two biopsies of normal tongue tissue were fixed in 2,5% phosphate-buffered glutaraldehyde, postfixed in 1% osmiumtetroxyde, embedded in Durcopan und contrasted ultrathin sections were examined by electron microscopes JEM 7A and 100B. The findings show a highly configurated epithel-connective tissue border with basal lamina and irregular hemidesmosomes. The epithelial structure of the interpapillary area is identical with the fine structure of the human buccal mucosa, which was classified as non-keratinized or incompletely keratinized. Accordingly, a stratum granulosum is missing. After loss of nucleus and organelles, surface cells become flattened, parallel to the surface of the tongue and have a fine fibrillar cytoplasm. The papilla filiformis is formed by cell growth along the secondary connective tissue papillae and consequently tube-like epithelial structures appear. In the papillary area basal and stratum spinosum cells show epidermal structural features. A difference from epidermal and other oral epithelial cells becomes apparent for the first time in the stratum granulosum by the appearance of a great number of round, small, electron-dense KHG, surrounded by ribosomes. The KHG are not associated with tonofilaments. In the area of the walls of the tubes 1...3 mum large, electron-dense structures are formed by fusion of several KHG. With further differentiation these large KHG disintegrate into bulky or granular masses, filling the cell cytoplasm and thus mask the tonofilaments. The cells at the borders of the tubes show a great structural variability. After the disintegration of nucleus and organelles, the cytoplasm is formed by randomly oriented filaments of different packing or by fiber-bundles. Yet the interfibrilla embedding substance, typical of orthokeratinization is mostly lackingmin some cells of the tubeborders, masses of disintegrated KHG substance are masking the fibrillar cell cytoplasm. In other areas, where the KHG do not increase by fusion, intense fibrillar packing and abrupt keratinization becomes apparent. At the rim of the tube fully keratinized epithelial threads are regularly found. These are lacking at the bottom of the tubes. All surface areas show a strong tendency towards desquamation. Thus a more or less wide surface plaque is formed on the tongue, consisting of desquamated and disintegrated surface cells and of bacterial. Groups of little differentiated basal cells, which can be considered as the initial material for an accelerated regeneration, can be evaluated as a truly remarkable finding. This accelerated regeneration might be due to an increased wear of the inclompletely keratinized cells of the bulk of the papilla filiformis of the human tongue. Based on the findings of this study, an attempt was made, to explain the pathological reactions of human tongue epithelium in various systemic diseases.     

Changes of the lingual epithelium in Ambystoma mexicanum

Changes in the lingual epithelium during ontogenesis and after induced metamorphosis in Ambystoma mexicanum are described as observed by light microscopy and scanning electron microscopy. The epithelium of the tongue is always multilayered in the larva as well as in the adult. It consists of a stratum germinativum with little differentiated basal cells and a stratum superficiale (superficial layer) with specialized superficial cells and goblet cells. Usually, there are more than two layers because of a stratum intermedium consisting of replacement cells. The apical cell membrane of the superficial cells is perforated by fine pores. Its most typical feature are microridges. Maturing superficial cells possess microvilli. Goblet cells occur in early larvae primarily in the centre of the tongue. They spread throughout the dorsal face of the tongue as their numbers increase during ontogenesis. The small apices of the goblet cells are intercalated in the wedges between the superficial cells. Leydig cells are not found on the larval tongue but on that of adults. Due to metamorphosis, the epithelium of the tongue changes. It is furrowed in its anterior part. The furrows house the openings of the lingual glands. The surface is further modulated by ridges which are densely coated by microvilli and which bear the taste buds. The villi of the tongue which lack extrusion pores show cilia and microvilli but lack microridges. The Leydig cells disappear during metamorphosis. In addition to the two types of goblet cells found in different regions of the glandular tubules, goblet cells occur in the caudal part. They secrete directly into the cavity of the mouth. The posterior part is characterised by a dense coat of cilia.     

SEX‐SPECIFIC CELL SURFACE STRUCTURE OF ANISOGAMETES: MORPHOLOGICAL CHANGES DURING FERTILIZATION OF BRYOPSIS MAXIMA (ULVOPHYCEAE,CHLOROPHYTA) REVEALED BY ULTRA–HIGH‐RESOLUTION FIELD EMISSION SEM1

Cell surfaces of biflagellate gametes and their morphological changes during fertilization of Bryopsis maxima Okamura were observed using a high‐resolution field emission scanning electron microscope. Male gametes have broad and narrow faces, which are divided into at least five morphologically distinct regions: 1) the apical plate is a plate‐like structure that is approximately 380–530 nm long and approximately 190 nm wide, in the center of the papilla and slightly protruded from the plasma membrane; 2) strips are smooth materials on ridges that originate from the basal part of the papilla and extend downward; 3) the lateral belt is a belt‐shaped structure on the center of the narrower faces; 4) the flagellar surface; and 5) the other region of the cell body has a fine‐grained appearance. In contrast, the entire female gamete surface is rough because of many granular or amorphous cell coats on the plasma membrane. When both gametes were mixed together, the initial fusion proceeded between the broader face of the male gamete and the anterior side of the female one near the basal bodies. Morphology of the male gamete's cell surface changed gradually as fusion proceeded and was covered by the granular materials; that surface closely resembled those of female gametes except for the apical plate. It was present until the planozygote attached itself to the substrate by the papilla. It finally disappeared after settlement. Therefore, these results indicate that gametes of B. maxima have sex‐specific surface structures that change their morphology during fertilization and settlement.     

Fetal development of the segment-specific papillary body in the equine hoof

Fetal development of the unique papillary body and its localized peculiarities in the equine hoof are described based on the study of 51 fetuses, nine newborn foals, and five adult horses. The shape and dimensions of the dermal papillae and lamellae have a formative influence on the structure and physical quality of the corneous hoof capsule with its horn tubules and lamellae. The size and arrangement of these horn structures determine the mechanical quality of hoof horn. Proper horn quality is a prerequisite for the various functions of the hoof capsule, such as protecting the living dermis supporting the hoof capsule, shock absorption, and formation of the suspensory apparatus of the distal phalanx. Development of the segment-specific papillary body is initiated by the increasing mitotic activity of the epidermal cells invaginating the dermal surface, thus forming dermal microridges. These microridges are transformed into single dermal papillae, which are arranged in rows, or enlarged to become primary and secondary dermal lamellae. The formation of a segment-specific papillary body enables the increasing keratinization ratio in the hoof epidermis and the formation of the characteristic tubular and lamellar horn responsible for the special mechanical properties of hoof horn.     

Anatomic features of postmortem experimental ruptures of the human heart

Comparison of postmortem performed experimental cardiac ruptures with post-infarction lesions reveals uniformity of their localization. The ruptures are found to occur at places of a sharp change in the relief of the cardiac internal surface. These areas should be considered as concentrators of strain, promoting cardiac ruptures. In the left ventricle six concentrators of strain are revealed. They are: the place where the anterior part of the interventricular septum passes into the anterior wall of the left ventricle, the right edge of the papillary muscle, the left edge of the anterior papillary muscle, the left edge of the posterior papillary muscle, the right edge of the posterior papillary muscle, the place where the posterior part of the interventricular septum passes into the posterior wall of the left ventricle. Frequency of the experimental ruptures of the interventricular septum, under loading of the left ventricle, is demonstrated to depend on pressure in the right cardiac part.     

Ultrastructural study of the precursor to fungiform papillae prior to the arrival of sensory nerves in the fetal rat.

The structure of precursors to fungiform papillae without taste buds, prior to the arrival of sensory nerve fibers at the papillae, was examined in the fetal rat on embryonic day 13 (E13) and 16 (E16) by light and transmission electron microscopy in an attempt to clarify the mechanism of morphogenesis of these papillae. At E13, a row of rudiments of fungiform papillae was arranged along both sides of the median sulcus of the lingual dorsal surface, and each row consisted of about 10 rudiments. There was no apparent direct contact between papillae rudiments and sensory nerves at this time. Bilaterally towards the lateral side of the tongue, adjacent to these first rudiments of fungiform papillae, a series of cord-like invaginations of the dorsal epithelium of the tongue into the underlying connective tissue, representing additional papillary primordia parallel to the first row, was observed. The basal end of each invagination was enlarged as a round bulge, indented at its tip by a mound of fibroblasts protruding into the bulge. At E16 there was still no apparent direct contact between rudiments of fungiform papillae and sensory nerves. Each rudiment apically contained a spherical core of aggregating cells, which consisted of a dense assembly of large, oval cells unlike those in other areas of the lingual dorsal epithelium. The differentiation of these aggregated cells was unclear. The basal lamina was clearly recognizable between the epithelium of the rudiment of fungiform papillae and the underlying connective tissue. Spherical structures, which appeared to be sections of the cord-like invaginations of the lingual epithelium that appeared on E13, were observed within the connective tissue separated from the dorsal lingual epithelium. Transverse sections of such structures revealed four concentric layers of cells: a central core, an inner shell, an outer shell, and a layer of large cells. Bundles of fibers were arranged in the central core, and the diameters of bundles varied somewhat depending on the depth of the primordia within the connective tissue and their distance from the median sulcus. Ultrastructural features of cells in the outer shell differed significantly in rudiments close to the lingual epithelium as compared to those in deeper areas of connective tissue. Around the outer shell there was a large-cell layer consisting of one to three layers of radially elongated, oval cells that contained many variously sized, electron-dense, round granules. Large numbers of fibroblasts formed dense aggregates around each spherical rudiment, and were separated by the basal lamina from the large-cell epithelial layer. Progressing from deep-lying levels of the rudiments of the papillae to levels close to the lingual surface epithelium, the central core, inner shell, and outer shell gradually disappeared from the invaginated papillary cords.     

Scanning electron microscope studies of some skink papillae basilares

Summary The papilla basilaris of scincid lizards is relatively long, slightly curved or bowed, and characteristically has an apical terminal expansion. A limbus-attached tectorial membrane is present but is apparently not continuous with the tectorial material covering the hair cells of the papilla. The hair cells of the apical expansion are covered by a thick spongy mass of tectorial material, while the hair cells above (dorsal to) the apical region are covered by thickened tectorial material that is in the form of uniquely sculptured, twisted or folded drape-like masses (sallets). The surface of the basal (dorsal) quarter of the papilla is unusual in that it is concave rather than convex. The expanded terminals of the hair cell kinocilia are also unusual in being arrowhead-shaped.Kinocilial orientation of the non-apical papillary hair cells is simply bidirectional; the hair cells on each side of the papillary axial midline are oriented toward the midline. Kinocilial orientation of the hair cells of the apical expansion is more complex with the peripheral neural and abneural rows both being abneurally directed, and the central rows being at first neural in orientation, but becoming abneurally oriented as the apical tip is approached. At the apical tip region, most all hair cells are abneurally oriented.I would like to thank Ms Maria Maglio for her skill in handling the technical aspects of the electron microscope, Mr. David Akers for expert photographic assistance, and Ms. Michiko Kasahara for aid in all aspects of the work. Research sponsored by United States Public Health Service Grant NS-09231.     

Fine structure of the dorsal lingual epithelium of the frog, Rana rugosa

Scanning and transmission electron microscopy was employed to investigate the ultrastructure of the lingual dorsal epithelial cells of the frog, Rana rugosa. The specimens for scanning electron microscopy were prepared by a method that involved osmium postfixation and treatment with acid to remove extracellular material that adhered to the surface of the tongue. Over almost the entire dorsal surface, filiform papillae, consisting of a large number of non-ciliated cells with microridges and a very small number of ciliated cells, were compactly distributed. Fungiform papillae were scattered among these filiform papillae. A round sensory disk was located on the top of each fungiform papilla. Each sensory disk was encircled by a band of ciliated cells. Transmission electron microscopy revealed that a large part of the filiform papillar epithelium was composed of cells that contained numerous electron-dense granules. These cells were coincident with the non-ciliated cells observed by scanning electron microscopy. In these cells, the nucleus was located on the basal side, and the ergastoplasm was well-developed on the basal side of the nucleus.     

小地老虎成虫直肠的发生和直肠乳突细胞功能性分化

本研究观察了小地老虎Agrotis ypsilon末龄幼虫、预蛹、蛹和成虫的直肠结构及成虫直肠乳突的细胞结构特点。结果表明：(1)成虫直肠是由幼虫的隐肾复合体解体后,原有幼虫直肠细胞经过分裂、重组和分化形成的,关键时期是预蛹至化蛹5d;(2)成虫直肠乳突呈圆盘形,自内向外包括内膜、乳突细胞、底膜、肌肉和围膜5层。乳突细胞按结构和功能特点分为帽状细胞、微气管细胞、网状细胞和盘底细胞4种;(3)试验发现成虫直肠膨大是由乳突体积扩增引起的。细胞结构剖析,直肠乳突有一整套完整而精细的结构,能扩增乳突体积和供应足够氧气及营养。文中还讨论了直肠的多种生理功能。     

Adhesive Papillae of Phallusia mamillata Larvae: Morphology and Innervation

The swimming larvae of most solitary ascidians belonging to the Ascidiidae family bear three anterior, simple conic adhesive papillae. They secrete adhesive substances that are used to effect transitory settlement at the beginning of the metamorphosis.The adhesive papillae of newly hatched Phallusia mamillata larvae examined by the SEM are covered by the tunic. When the larvae are about to settle, the tunic becomes fenestrated over the central part of the papilla and bulb-ended microvilli protrude through the holes. These papillae have two types of elongated cells: many peripheral cells and few larger central cells with microvilli and bundles of microtubules oriented along the major axis of the cells.We have done immunofluorescence experiments with an anti-beta-tubulin monoclonal antibody (clone 2-28-33) reacting with axonal microtubules. Only the central cells of the papillae were stained and the axons appeared to arise from the proximal ends of these cells. These axons form a long nerve that reaches the brain vesicle. Branches of the same nerve appear to connect to the basal ends of the peripheral cells. By confocal laser microscopy we were able to follow the course of the papillary nerve. The two nerves connecting the dorsal papillae fuse together into a single nerve that runs posteriorly. The nerve connecting the ventral papilla runs posteriorly for a long tract before fusing with the nerve of the dorsal papillae just near the brain.The reported observations raise the hypothesis that the central cells of the adhesive papillae might be primary sensory neurons and that they may have chemosensory function.     

The fine structure of epidermal papillae of Travisia forbesii (Annelida)

The structure of the epidermis of Travisia forbesii was described using light and electron microscopy. The epidermis is a highly modified variant of the normal one-layer polychaete epithelium. It consists of basal epidermal cells and an external layer of closely sited papillae consisting of glandular and supportive epidermal cells, and extensive electron-transparent intercellular spaces. The papillae are embedded in the thick cuticle. Each papilla has a peduncle, which is formed by one cell that penetrates the inner cuticle layer to the basal epidermal cells. A fold of basement membrane forms the core of the peduncle and ends in the base of a papilla. All epidermal cells are connected to each other with apical cell junctions and to the basement membrane with hemidesmosomes, so the epithelium is continuous and uninterrupted. The epidermis has an intra-epidermal neuron plexus. The structure of the papillae is compared with papillae and tubercles of other polychaetes, and the possible functional significance and phylogenetic implications of these structures are discussed.     

Light- and electron-microscopic observations of the tail bud of the larval lamprey (Lampetra japonica), with special reference to neural tube formation

Serial transverse and horizontal sections of the tail of the 26-day larval lamprey, Lampetra japonica, were observed by light and electron microscopy. The axial structures in the tail of the larval lamprey seem to differentiate from the prospective materials derived individually from the tail bud. The latter consists of two closely adjoined cell populations (C1 and C2). C1 is a small cell cluster located posterior to the other group (C2) and consists of loosely arranged polymorphous cells. The cell cluster extends cranially as a cell sheet on the ventral surface of C2; somites differentiate from this cell sheet. C2 is composed of cells elongated mediolaterally and stacked horizontally to form a compact cell mass which is covered on each lateral surface by a basal lamina. The upper one-third of C2 seems to differentiate into the neural tube, anteceding other axial structures. The middle one-third of C2 seems to develop into the notochord, and the lower one-third into the subchord and the undefined cell cord. The central canal develops in the upper one-third of C2 through the following events: 1) appearance of cilia and a small cavity between adjoining cells; 2) appearance of microvilli in the cavity, in addition to cilia; and 3) development of junctional complexes along the luminal borders of cells surrounding the cavity. Together with these events, cells surrounding the cavity increase in number, acquiring apicobasal polarity and radial arrangement. The cavity itself enlarges by incorporation of periciliary clefts and fusion of cavities with each other to establish the central canal. Near the caudal end of the neural tube, the central canal is directly confluent with the connective-tissue space through an opening in the dorsal wall of the neural tube.     

FINE STRUCTURE OF ZOOSPOROGENESIS, ZOOSPORE GERMINATION, AND EARLY GAMETOPHYTE DEVELOPMENT IN CLADOPHORA SURERA (CLADOPHORALES, CHLOROPHYTA)

The fine structure of zoosporogenesis, zoospore germination, and early gametophyte development in Cladophora surera Parodi et Cáceres were studied. Zoosporogenesis started with simultaneous meiosis in all nuclei of apical initial cells. The resulting haploid nuclei duplicated in turn by successive centric, closed mitoses. Then, each initial cell divided into two short zoosporangia. Numerous vacuoles appeared around each sporic nucleus. The delimitation of uninucleate zoosporocytes occurred by cytokinetic furrows produced by the coalescence of tiny, clear vesicles, without microtubules. Final shape of the zoospore resulted from gradual expulsion of vacuoles from the cell body. Mature biflagellate zoospores exhibited a conspicuous apical papilla containing fine granular globules, the basal apparatus, and a microtubular "umbrella" formed by numerous cortical microtubules that ran backward the length of the cell body. The chloroplast showed a conspicuous eyespot. The zoosporangial wall disorganized at the pore through which the zoospores were liberated. Zoospores settled on a substrate by their anterior papilla secreting an adhesive. Germination involved retraction of the apical papilla, loss of the "umbrella" microtubules and eyespot, and the lateral absorption of the entire flagellar apparatus, i.e. basal apparatus plus axoneme, into the cytoplasm. Early gametophyte development involved the synthesis of a thin, young cell wall, the development of outer peripheral vacuoles, the appearance of the marginal reticulate chloroplast, and the formation of the first central vacuoles derived from abundant endoplasmic reticulum. Close to the plasmalemma ran longitudinally oriented cortical microtubules. Eventually, the germling developed an achlorophylic, elongated rhizoidal portion.     

On the Fine Structure of the Alimentary Tract of Cephalodiscus gracilis (Pterobranchia,Hemichordata)

The U-shaped alimentary tract of Cephalodiscus is of exclusively epithelial structure; on the basis of fine structural criteria the entire tract can be divided into two large subdivisions: an anterior one with mouth, mouth cavity, pharynx and oesophagus, and a posterior one with stomach and intestine. The anterior subdivision is built up of a relatively uniform, innervated, pseudostratified, ciliated epithelium with mucus cells which are concentrated in the initial parts of the mouth cavity. Cilia and mucus presumably constitute a mechanism transporting food particles into the stomach. In the area of the gill slits specific vacuolated cells occur which may lend rigidity to the walls of the slits. The gastric epithelium consists of prismatic cells characterized by, among others, large inclusion bodies, which may represent digestive vacuoles, small dense rod-shaped granules and an elaborate system of microridges, at the base of which abundant endocytotic vesicles occur. The dorsal gastric pouch contains cells rich in rough ER and secretory granules, probably containing digestive enzymes. Thus morphological evidence points both to intra- and extracellular digestion. The intestinal epithelium resembles that of the stomach, however, it is lower, its organelles are fewer and it bears, beside cilia, mainly microridges, which towards its distal end become sparse. Both in the gastric and intestinal epithelium small granulated cells have been found, which presumably represent endocrine cells.     

Two modes of information processing in the electrosensory system of the paddlefish (Polyodon spathula)

Paddlefish are uniquely adapted for the detection of their prey, small water fleas, by primarily using their passive electrosensory system. In a recent anatomical study, we found two populations of secondary neurons in the electrosensory hind brain area (dorsal octavolateral nucleus, DON). Cells in the anterior DON project to the contralateral tectum, whereas cells in the posterior DON project bilaterally to the torus semicircularis and lateral mesencephalic nucleus. In this study, we investigated the properties of both populations and found that they form two physiologically different populations. Cells in the posterior DON are about one order of magnitude more sensitive and respond better to stimuli with lower frequency content than anterior cells. The posterior cells are, therefore, better suited to detect distant prey represented by low-amplitude signals at the receptors, along with a lower frequency spectrum, whereas cells in the anterior DON may only be able to sense nearby prey. This suggests the existence of two distinct channels for electrosensory information processing: one for proximal signals via the anterior DON and one for distant stimuli via the posterior DON with the sensory input fed into the appropriate ascending channels based on the relative sensitivity of both cell populations.     

Fine structure of the dorsal lingual epithelium of the little tern, Sterna albifrons Pallas (Aves, Lari).

The dorsal surface of the tongue of the little tern, Sterna albifrons, has a distinctive anterior region for five-sixths of its length and a terminal posterior region. The anterior region observed by scanning electron microscopy is distinguished along its forward half by a median line from which median papillae protrude. The hind half of the anterior region has a median sulcus without papillae. The deciduous epithelium on both sides of the median line and sulcus bears scattered epithelial protrusions. The posterior lingual region has neither median papillae nor deciduous epithelium. So-called giant conical papillae are located in a transverse row between anterior and posterior regions. Delicate microridges adorn the surfaces of all outer epithelial cells in both regions. Examination of the dorsal lingual epithelium by light and electron microscopy provides histologic and cytologic criteria for distinguishing anterior and posterior regions. Basal cells are nearly alike throughout the dorsal epithelium. Intermediate layer cells of the anterior region contain numerous tonofibrils in electron-dense bundles composed of 10 nm tonofilaments. The outer layer is composed of electron-dense, well-keratinized cells, and electron-lucent epithelial protrusions are present on the exposed surface of the outermost cells. Median papillae are composed of typical keratinized cells, which are nearly filled with keratin filaments. Intermediate layer cells in the posterior region of the tongue are nearly filled with unbundled tonofilaments. There is only a very thin outer keratinized layer in this region.     

黄斑篮子鱼和金钱鱼鳃的扫描电镜观察

对两种鲈形目鱼类黄斑篮子鱼(Siganus oramin)和金钱鱼(Scatophagus argus)的鳃结构进行扫描电镜观察。结果表明,黄斑篮子鱼和金钱鱼鳃的表面结构及微细结构与其他硬骨鱼类基本相似,鳃丝表面都具有规则或不规则分布的环形微嵴、沟、坑、孔等结构。黄斑篮子鱼的鳃片中部鳃丝表皮有大量凸起,而端部鳃丝表皮的凹凸程度明显较低,黄斑篮子鱼的鳃小片高度较金钱鱼鳃小片高。黄斑篮子鱼和金钱鱼鳃上皮的扁平上皮细胞、氯细胞和黏液细胞的形态结构及数量分布存在细微的差异。黄斑篮子鱼鳃片鳃丝的端部和中部表面有黏液细胞,金钱鱼鳃丝表面的黏液细胞很难观察到,与大多数淡水鱼类相似。黄斑篮子鱼鳃丝表面分布的氯细胞数量多于金钱鱼,这可能与两种鱼生活环境、生活习性的长期演变相关。