Showing papers on "Ultrastructure published in 2012"

How wood evolves: a new synthesis

Abstract: Recent advances in wood physiology, molecular phylogeny, and ultrastructure (chiefly scanning electron microscopy, SEM), as well as important new knowledge in traditional fields, provide the basis ...

Visualization of yeast cells by electron microscopy

Abstract: In the 1970s, hydrocarbon or methanol utilizable yeasts were considered as a material for foods and ethanol production. During the course of studies into the physiology of yeasts, we found that these systems provide a suitable model for the biogenesis and ultrastructure research of microbodies (peroxisomes). Microbodies of hydrocarbon utilizing Candida tropicalis multiply profusely from the preexisting microbody. β oxidation enzymes in the microbody were determined by means of immunoelectron microscopy. We examined the ultrastructure of Candida boidinii microbodies grown on methanol, and found a composite crystalloid of two enzymes, alcohol oxidase and catalase, by analyzing using the optical diffraction and filtering technique and computer simulation. We established methods for preparing the protoplasts of Schizosaccharomyces pombe and conditions for the complete regeneration of the cell wall. The dynamic process of cell wall formation was clarified through our study of the protoplasts, using an improved ultra high resolution (UHR) FESEM S-900 and an S-900LV. It was found that β-1,3-glucan, β-1,6-glucan and α-1,3-glucan, as well as α-galactomannan, are ingredients of the cell wall. The process of septum formation during cell division was examined after cryo-fixation by high pressure freezing (HPF). It was also found that α-1,3- and β-1,3-glucans were located in the invaginating nascent septum, and later, highly branched β-1,6-glucan also appeared on the second septum. The micro-sampling method, using a focused ion beam (FIB), has been applied to our yeast cell wall research. A combination of FIB and scanning transmission electron microscopy is useful in constructing 3D images and analyzing the molecular architecture of cells, as well as for electron tomography of thick sections of biological specimens.

Salinity-induced subcellular accumulation of H 2 O 2 in leaves of rice

Abstract: The localization of salt-induced H2O2 accumulation in the leaves of rice was examined using 3,3-diaminobenzidine and CeCl3 staining at ultrastructure level. When the 3-week-old rice plants were affected by 100 mM NaCl for 14 days, the swelling of thylakoids and the destruction of thylakoid membranes were observed. H2O2 accumulation was also observed in the chloroplast of the leaf treated with NaCl. The electron dense products of 3,3-diaminobenzidine and CeCl3 were mainly observed especially around the swelling of thylakoids. H2O2 accumulation and any ultrastructural changes were not observed in the chloroplasts under dark condition. Furthermore, treatment with ascorbic acid suppressed both H2O2 accumulation and the changes in chloroplast ultrastructure. These results suggest that light-induced production of excess H2O2 under salinity is responsible for the changes in chloroplast ultrastructure. H2O2 accumulation was also observed in the mitochondria, peroxisomes, plasma membrane, and cell walls under light but not dark, suggesting that these organelles are also the source of H2O2 and the production is light dependent under salinity.

Analysis of the cell surface layer ultrastructure of the oral pathogen Tannerella forsythia

Abstract: The Gram-negative oral pathogen Tannerella forsythia is decorated with a 2D crystalline surface (S-) layer, with two different S-layer glycoprotein species being present. Prompted by the predicted virulence potential of the S-layer, this study focused on the analysis of the arrangement of the individual S-layer glycoproteins by a combination of microscopic, genetic, and biochemical analyses. The two S-layer genes are transcribed into mRNA and expressed into protein in equal amounts. The S-layer was investigated on intact bacterial cells by transmission electron microscopy, by immune fluorescence microscopy, and by atomic force microscopy. The analyses of wild-type cells revealed a distinct square S-layer lattice with an overall lattice constant of 10.1 ± 0.7 nm. In contrast, a blurred lattice with a lattice constant of 9.0 nm was found on S-layer single-mutant cells. This together with in vitro self-assembly studies using purified (glyco)protein species indicated their increased structural flexibility after self-assembly and/or impaired self-assembly capability. In conjunction with TEM analyses of thin-sectioned cells, this study demonstrates the unusual case that two S-layer glycoproteins are co-assembled into a single S-layer. Additionally, flagella and pilus-like structures were observed on T. forsythia cells, which might impact the pathogenicity of this bacterium.

Changes in cell ultrastructure and inhibition of JAK1/STAT3 signaling pathway in CBRH-7919 cells with astaxanthin

Abstract: Astaxanthin (AST), a xanthophylls carotenoid, possesses significant anticancer effects. However, to date, the molecular mechanism of anticancer remains unclear. In the present research, we studied the anticancer mechanism of AST, including the changes in cell ultrastructure, such as the mitochondrion, rough endoplasmic reticulum (RER), Golgi complex, and cytoskeleton, the inhibition of Janus kinase 1(JAK1)/transduction and the activators of the transcription-3 (STAT3) signaling pathway using rat hepatocellular carcinoma CBRH-7919 cells. Cell apoptosis was evaluated and the expressions of JAK1, STAT3, non-metastasis23-1 (nm23-1), and apoptotic gene like B-cell lymphoma/leukemia-2 (bcl-2), B-cell lymphoma-extra large (bcl-xl), proto-oncogene proteins c myc (c-myc) and bcl-2- associated X (bax) were also examined. The results showed that AST could induce cancer cell apoptosis. Under transmission electron microscope, the ultrastructure of treated cells were not clearly distinguishable, the membranes of the mi...

Coccolithogenesis In Scyphosphaera apsteinii (Prymnesiophyceae).

Abstract: Coccolithophores are the most significant producers of marine biogenic calcite, although the intracellular calcification process is poorly understood. In the case of Scyphosphaera apsteinii Lohmann 1902, flat ovoid muroliths and bulky, vase-shaped lopadoliths with a range of intermediate morphologies may be produced by a single cell. This polymorphic species is within the Zygodiscales, a group that remains understudied with respect to ultrastructure and coccolith ontogeny. We therefore undertook an analysis of cell ultrastructure, morphology, and coccolithogenesis. The cell ultrastructure showed many typical haptophyte features, with calcification following a similar pattern to that described for other heterococcolith bearing species including Emiliania huxleyi. Of particular significance was the reticular body role in governing fine-scale morphology, specifically the central pore formation of the coccolith. Our observations also highlighted the essential role of the inter- and intracrystalline organic matrix in growth and arrangement of the coccolith calcite. S. apsteinii secreted mature coccoliths that attached to the plasma membrane via fibrillar material. Time-lapse light microscopy demonstrated secretion of lopadoliths occurred base first before being actively repositioned at the cell surface. Significantly, growth irradiance influenced the coccosphere composition with fewer lopadoliths being formed relative to muroliths at higher light intensities. Overall, our observations support dynamic metabolic (i.e., in response to growth irradiance), sensory and cytoskeletal control over the morphology and secretion of polymorphic heterococcoliths. With a basic understanding of calcification established, S. apsteinii could be a valuable model to further study coccolithophore calcification and cell physiological responses to ocean acidification.

Chilling-induced ultrastructural changes to mesophyll cells of Arabidopsis grown under short days are almost completely reversible by plant re-warming.

Abstract: Exposure of plants to chilling (low temperatures above freezing) limits growth and development in all environments outside the lowest latitudes. Cell ultrastructure and morphometric studies may allow associations to be made between chilling-induced changes at the ultrastructural level, molecular events and their physiological consequences. We examined changes in the shape, size and membrane organization of the organelles of mesophyll cells in Arabidopsis thaliana (Col 0), a cold-resistant species, after subjecting 6-week-old plants grown at normal growth temperatures to chilling (2.5–4°C; 14-h dark/10-h light cycle) for 6, 24 and 72 h and after a re-warming period of 50 h. No ultrastructural differences were seen in the first 6 h of chilling but after 24 h we observed swollen and rounded chloroplasts with larger starch grains and dilated thylakoids compared to control plants. By 72 h, chilling had resulted in a large accumulation of starch in chloroplasts, an apparent crowding of the cytosol and a lower abundance of peripheral reticulum than in the controls. The average area per chloroplast in cell sections increased after 72-h chilling while the number of chloroplasts remained the same. Ring-shaped and other morphologically aberrant mitochondria were present in significantly higher abundance in plants given 72 h chilling than in the controls. Plant re-warming for 50 h reduced chloroplast size to those of the controls and returned mitochondria to standard morphology, but peripheral reticulum remained less abundant than in plants never given a cold treatment. The near full return to normal ultrastructure upon plant re-warming indicates that the morphological changes may be part of acclimation to cold.

Oleoresin glands in copaíba (Copaifera trapezifolia Hayne: Leguminosae), a Brazilian rainforest tree

Abstract: Although studies have addressed the chemical analysis and the biological activity of oleoresin in species of Copaifera, the cellular mechanisms of oleoresin production, storage, and release have rarely been investigated. This study detailed the distribution, ontogeny, and ultrastructure of secretory cavities and canals distributed in leaf and stem, respectively, of Copaifera trapezifolia, a Brazilian species included in a plant group of great economic interest. Axillary vegetative buds, leaflets, and portions of stem in primary and secondary growth were collected and processed in order to study the anatomy, histolocalization of substances, and ultrastructure. Secretory cavities are observed in the foliar blade and secretory canals in the petiolule and stem. They are made up of a uniseriate epithelium delimiting an isodiametric or elongated lumen. Biseriate epithelium is rarely observed and is a novelty for Leguminosae. Cavities and canals originate from ground meristem cells and the lumen is formed by schizogenesis. The content of the cavities and canals of both stem and leaf is oily and resinous, which suggests that the oleoresin could be extracted from the leaf instead of the stem. Phenolic compounds are also detected in the epithelial cell cytoplasm. Cavities and canals in the beginning of developmental stages have polarized epithelial cells. The cytoplasm is rich in smooth and rough endoplasmic reticula connected to vesicles or plastids. Smooth and rough endoplasmic reticulum and plastids were found to be predominant in the epithelial cells of the secretory cavities and canals of C. trapezifolia. Such features testify the quantities of oleoresin found in the lumen and phenolic compounds in the epithelial cell cytoplasm of these glands. Other studies employing techniques such as correlative light electron microscopy could show the vesicle traffic and the compartmentalization of the produced substances in such glands.

Ultrastructure and Glycoconjugate Pattern of the Foot Epithelium of the Abalone Haliotis tuberculata (Linnaeus, 1758) (Gastropoda, Haliotidae)

Abstract: The foot epithelium of the gastropod Haliotis tuberculata is studied by light and electron microscopy in order to contribute to the understanding of the anatomy and functional morphology of the mollusks integument. Study of the external surface by scanning electron microscopy reveals that the side foot epithelium is characterized by a microvillus border with a very scant presence of small ciliary tufts, but the sole foot epithelium bears a dense field of long cilia. Ultrastructural examination by transmission electron microscopy of the side epithelial cells shows deeply pigmented cells with high electron-dense granular content which are not observed in the epithelial sole cells. Along the pedal epithelium, seven types of secretory cells are present; furthermore, two types of subepithelial glands are located just in the sole foot. The presence and composition of glycoconjugates in the secretory cells and subepithelial glands are analyzed by conventional and lectin histochemistry. Subepithelial glands contain mainly N-glycoproteins rich in fucose and mannose whereas secretory cells present mostly acidic sulphated glycoconjugates such as glycosaminoglycans and mucins, which are rich in galactose, N-acetyl-galactosamine, and N-acetyl-glucosamine. No sialic acid is present in the foot epithelium.

3D Morphology, Ultrastructure and Development of Ceratomyxa puntazzi Stages: First Insights into the Mechanisms of Motility and Budding in the Myxozoa

Abstract: Free, amoeboid movement of organisms within media as well as substrate-dependent cellular crawling processes of cells and organisms require an actin cytoskeleton. This system is also involved in the cytokinetic processes of all eukaryotic cells. Myxozoan parasites are known for the disease they cause in economical important fishes. Usually, their pathology is related to rapid proliferation in the host. However, the sequences of their development are still poorly understood, especially with regard to pre-sporogonic proliferation mechanisms. The present work employs light microscopy (LM), electron microscopy (SEM, TEM) and confocal laser scanning microscopy (CLSM) in combination with specific stains (Nile Red, DAPI, Phalloidin), to study the three-dimensional morphology, motility, ultrastructure and cellular composition of Ceratomyxa puntazzi, a myxozoan inhabiting the bile of the sharpsnout seabream. Our results demonstrate the occurrence of two C. puntazzi developmental cycles in the bile, i.e. pre-sporogonic proliferation including frequent budding as well as sporogony, resulting in the formation of durable spore stages and we provide unique details on the ultrastructure and the developmental sequence of bile inhabiting myxozoans. The present study describes, for the first time, the cellular components and mechanisms involved in the motility of myxozoan proliferative stages, and reveals how the same elements are implicated in the processes of budding and cytokinesis in the Myxozoa. We demonstrate that F-actin rich cytoskeletal elements polarize at one end of the parasites and in the filopodia which are rapidly de novo created and re-absorbed, thus facilitating unidirectional parasite motility in the bile. We furthermore discover the myxozoan mechanism of budding as an active, polarization process of cytokinesis, which is independent from a contractile ring and thus differs from the mechanism, generally observed in eurkaryotic cells. We hereby demonstrate that CLSM is a powerful tool for myxozoan research with a great potential for exploitation, and we strongly recommend its future use in combination with in vivo stains.

Ultrastructural insights into morphology and reproductive mode of Blastocystis hominis

Abstract: To understand well the morphology and reproductive mode of Blastocystis hominis, with the help of transmission electron microscopy and scanning electron microscopy the ultrastructural details of B. hominis from fresh diarrheal specimens and cultured strains were observed. In both fecal samples and culture conditions, there were vacuolar and granular forms. In diarrhea, it exists in multivacuolar, avacuolar, and amoeboid forms. In the in vitro culture, vacuolar form could transform to granular form. The most commonly noticed structure on the cell surface was surface coat with diversity in appearance (the funiform, lamellar, filiform, and floccose in different thickness) and distributions. Three modes of reproduction were confirmed, they were binary fission, plasmotomy, and budding. Under the impact of host’s response, the ultrastructures of surface coat, nucleus, and mitochondrion-like organelle sometimes changed.

Correlative light and electron microscopy in parasite research.

Abstract: The interaction of a parasite and a host cell is a complex process, which involves several steps: (1) attachment to the plasma membrane, (2) entry inside the host cell, and (3) hijacking of the metabolism of the host. In biochemical experiments, only an event averaged over the whole cell population can be analyzed. The power of microscopy, however, is to investigate individual events in individual cells. Therefore, parasitologists frequently perform experiments with fluorescence microscopy using different dyes to label structures of the parasite or the host cell. Though the resolution of light microscopy has greatly improved, it is not sufficient to reveal interactions at the ultrastructural level. Furthermore, only specifically labeled structures can be seen and related to each other. Here, we want to demonstrate the additional value of electron microscopy in this area of research. Investigation of the different steps of parasite-host cell interaction by electron microscopy, however, is often hampered by the fact that there are only a few cells infected, and therefore it is difficult to find enough cells to study. A solution is to profit from low magnification, hence large overview, and specific location of the players by fluorescence labels in a light microscope with the high power resolution and structural information provided by an electron microscope, in short by correlative light and electron microscopy.

The pine-cone body: an intermediate structure between the cap mesenchyme and the renal vesicle in the developing nod mouse kidney revealed by an ultrastructural study

Abstract: Nephrogenesis is mainly characterized by the interaction of two distinct renal constituents, the ureteric bud and the metanephric mesenchyme. In this paper we describe by means of light and electron microscopic techniques the morphological events that take place during the early stages of cap mesenchymal formation. Samples of normal renal tissue were excised from newborn NOD mice and processed by standard light and electron microscopy techniques. In all samples examined we detected the presence of several cap mesenchymal aggregates in different stages of differentiation. They varied from small solid nodules with few ovoid cells to bigger pine-cone-like aggregates, characterized by a peculiar distribution and morphology of their cellular constituents. Our data highlight, for the first time, the presence of a specific cap mesenchymal structure, the pine-cone body and show, at ultrastructural level, how each cap aggregate epithelializes proceeding in stages from a condensed mesenchymal aggregate to the renal...

Morphological characterization of the immune organs in ostrich chicks

Abstract: This study describes the anatomical, light microscopic, and ultrastructural characterization of the immune organs in ostrich chicks. In this study 6 healthy 8-week-old ostrich chicks were processed for light and transmission electron microscopy. Hematoxylin and eosin as well as improved Weigert staining were used for light microscopy. The small thymus, which clustered caudally along both sides of the neck, contained Hassall's corpuscles in the medulla. The cloacal bursa, which formed the hanging and lateral walls of the cloaca, enveloped the cloaca but did not form a truly independent bursa. Inside the bursa convex papillae were densely distributed on the surface of the folds, each with a single bursal nodule in the lamina propria. There were several round or elliptical structures, similar to ellipsoids, in the parenchyma of the spleen. Homogeneous acidophilic material was found to exist between the ellipsoid and the lymph tissue, and intermittent transverse striations were detected by transmission electron microscopy. These data indicate that the immune organs of ostrich chicks, especially the spleen and cloacal bursa, have numerous distinct, conformational, and structural features. The acidophilic material between the ellipsoid analog and circum-lymph tissue of the spleen, which was identified as collagen fiber, has not been reported in other animals.

Glandular trichomes of Ceratotheca triloba (Pedaliaceae): morphology, histochemistry and ultrastructure

Abstract: This study was initiated to characterize the distribution, morphology, secretion mode, histochemistry and ultrastructure of the glandular trichomes of Ceratotheca triloba using light and electron microscopy. Its leaves bear two morphologically distinct glandular trichomes. The first type has long trichome with 8–12 basal cells of pedestal, 3–14 stalk cells, a neck cell and a head of four cells in one layer. The second type has short trichome comprising one or two basal epidermal cells, a unicellular or bicellular stalk and a multicellular head of two to eight cells. There is a marked circular area in the upper part of each head cell of the long trichome. This area is provided with micropores to exudate directly the secretory product onto the leaf surface by an eccrine pathway. The secretory product has copious amount of dark microbodies arising from plastids which are positive to Sudan tests and osmium tetroxide for unsaturated lipids. The secretion mode of short trichomes is granulocrine and involves two morphologically and histochemically distinct vesicle types: small Golgi-derived vesicles which are positive to Ruthenium Red test for mucilaginous polysaccharides; the second type is dark large microbodies similar to that of long trichomes with low quantity. These two types are stored in numerous peripheral vacuoles and discharge their contents accompanied by the formation of irregular invaginations of the plasmalemma inside the vacuoles via reverse pinocytosis. These two secretion modes of long and short trichomes are reported for the first time in the family Pedaliaceae. The long trichomes have more unsaturated lipids, while the short trichomes contain more mucilaginous polysaccharides.

Central nervous system of Rhipicephalus sanguineus ticks (Acari: Ixodidae): an ultrastructural study

Abstract: This study performed the ultrastructural description of the synganglion of Rhipicephalus sanguineus males and females, aiming to contribute to the understanding of the cellular organization of this organ. The results show that the central nervous system of these individuals consists of a mass of fused nerves, named synganglion, from where nerves emerge towards several parts of the body. It is surrounded by the neural lamella, a uniform and acellular layer, constituted by repeated layers of homogeneous and finely granular material. The perineurium is just below, composed of glial cells, which extensions invaginate throughout the nervous tissue. The synganglion is internally divided into an outer cortex, which contains the cellular bodies of the neural cells and an inner neuropile. The neural cells can be classified into two types according to cell size, cytoplasm–nucleus relation, and neurosecretory activity. Type I cells are oval or spherical and present a large nucleus occupying most part of the cytoplasm, which contains few organelles. Type 2 cells are polygonal, present a great cytoplasm volume, and their nuclei are located in the cell periphery. The cytoplasm of these cells contains a well-developed rough endoplasmic reticulum, Golgi regions, mitochondria, and several neurosecretory granules. The subperineurium and the tracheal ramifications are found between the cortex and the neuropile. The latter is formed mainly by neural fibers, tracheal elements, and glial cells. The results obtained show that R. sanguineus males' and females' nervous tissue present an ultrastructural organization similar to the one described in the literature for other tick species.

Effect of Tomato yellow leaf curl bigeminivirus (TYLCV) infection on tomato cell ultrastructure and physiology

Abstract: Tomato yellow leaf curl bigeminivirus was isolated in Kuwait and therefore designated as TYLCV-K. The virus was found to be transmitted by whiteflies (Bemisia tabaci Genn.), and produced the characteristic external symptoms on tomato (Solanum lycopersicum L.) test plants. Electron microscopy of ultra-thin sections of infected leaves showed alterations in the ultrastructure of some organelles and uneven thickenings of the cell wall of the phloem tissue associated with severe damage in chloroplasts and abnormal building up of oily inclusions and empty vacuoles. The causal virus was characterized as a whitefly-transmitted monopartite Geminivirus. Viral genomic DNA fragment of 1.1 kb was successfully amplified from TYLCV-K infected tissues using polymerase chain reaction (PCR). The virus identity was confirmed by using Southern and dot-blot hybridizations. Chemical components of tomato leaves, such as photosynthetic pigments, especially chlorophyll a and b, total lipids, saturated and unsaturated fat...

Embryogenesis and larval ultrastructure in Paraleucilla magna (Calcarea, Calcaronea), with remarks on the epilarval trophocyte epithelium (“placental membrane”)

Abstract: The process of inversion observed during the development of Calcaronea (Calcarea, Porifera) species is a unique and remarkable event in the Metazoa. However, few studies have focused on the embryogenesis of Calcaronea species or on the ultrastructure of their larva and its accessory epithelium, the so-called placental membrane. Herein, using light and electron microscopy, we describe the embryogenesis and ultrastructure of the amphiblastula of Paraleucilla magna (Porifera, Calcarea, Calcaronea). It was observed that the cleavage in this species is of the table-like palyntomy type, typical of calcaroneans. Cleavage leads to the formation of a stomoblastula, which becomes inverted in the mesohyl. At the same time, the accessory epithelium (here called epilarval trophocyte epithelium) rises, isolating and nursing the early larva. The amphiblastula is formed by an epithelium composed of ciliated cells, granular cells, and cross-cells, this latter persisting even after larval release. Some degenerating amoeboid cells and bacteria were found in the larval cavity, possibly helping with larval nutrition. The possibility of cross-cells being precursors of the germ cell lineage and the vertical transmission of bacteria found in the larva are discussed.

Ultrastructure of Candida albicans pleomorphic forms: phase-contrast microscopy, scanning and transmission electron microscopy.

Abstract: A b s t r a c t A modified method of glutaraldeyde-osmium tetroxide fixation was adjusted to characterize the ultrastructure of Candida albicans pleomorphic forms, using phase-contrast microscopy, scanning electron microscopy and transmission electron microscopy. &e discovered morphological criteria defining the individual morphotypes are discussed in terms of mycological and histopathological diagnostics of candidiasis. &e relations are discussed between fungal pleomorphism, virulence and susceptibility of di!erent morphotypes to fungicides.

A fresh look at Dinodasys mirabilis (Gastrotricha, Macrodasyida), with focus on the reproductive apparatus and sperm ultrastructure

Abstract: Adults of Dinodasys mirabilis were studied for the first time. The specimens, collected from the west coast of Sweden, were investigated alive and with electron microscopy. Sexually mature specimens attain a total length of 450–490 μm; the adhesive apparatus is made up of anterior, lateral, ventrolateral, dorsal and posterior tubes; and one pair of “cirrata” type tubes is also present. The reproductive apparatus is hermaphroditic, paired testes extend rearward from the pharyngeo-intestinal junction to 3/4 of the trunk, and sperm ducts bend anteriorly at U52 and join together into a common, mid-ventral pore at U33. Two ovaries lie along the sides of the caudal intestine, extending anteriorly from U68. Frontal organ present on the right side of the body centered a U70; caudal organ was absent; a gland organ surrounding the terminal intestine may be present, but its homology with other organs in a similar position is uncertain. The spermatozoon is a filiform cell, formed by a long acrosome, a spring-like nucleus and a flagellum. The acrosome is divided into two regions: the anterior-most is thin and corkscrew-shaped, and the posterior one is rectilinear; both regions are delimited by a continuous external layer of thick, dense material, which in longitudinal section appears obliquely striated and surrounds a long pile of stout, electron-dense cylinders; the nucleus contains condensed chromatin and is coiled around an elongate mitochondrion; the flagellum possesses a 9 × 2 + 2 axoneme devoid of striated cylinder. Within Macrodasyida, U-bend sperm ducts and the peculiar ultrastructure of the acrosome are characteristics shared by other Turbanellidae studied so far, providing a foundation for the current systematization of Dinodasys.

Liver anatomy, histochemistry, and ultrastructure of Eupemphix nattereri (Anura: Leiuperidae) during the breeding season.

Abstract: The arrangement of the hepatic tissue is directly related to physiological characteristics of animals, such as ectothermy, diet, and reproductive status. Here, we describe the anatomy, histology, and ultrastructure of the liver in adult males of Eupemphix nattereri during the breeding season. The liver is an organ with an irregular shape, red in color, and occupies a large portion of the body cavity. Anatomically, it is divided into three lobes: right, mid, and left. Further subdivision into lobules is not observed. A thin capsule of connective tissue covers externally the organ, which is responsible for its support and protection. The hepatic parenchyma is formed by two layers of polyhedralshaped hepatocytes arranged in a double cordon. These cordons are filled with hepatic sinusoids that greatly vary in size and are closely associated with hepatocytes. There are also bile canaliculi and immune cells between hepatic cordons—the melanomacrophages. These canaliculi are covered with short microvilli, which protrude into the lumen. Melanomacrophages have several cytoplasmic substances, such as melanin, lipofuscin, and hemosiderin, which form due to liver metabolism and contribute to the typical coloration of the organ. A large amount of mitochondria and other organelles, such as a well-developed Golgi apparatus, smooth endoplasmic reticulum, and abundant glycogen are found in the cytoplasm of hepatocytes.