MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF DICHELYNE (NEOCULLANELLUS) DAKARENSIS N. SP. (NEMATODA: CUCULLANIDAE) PARASITIZING AN ECONOMICALLY IMPORTANT MARINE FISH, THE SOMPAT GRUNT, POMADASYS JUBELINI (PERCIFORMES: HAEMULIDAE), FROM HANN BAY IN DAKAR, SENEGAL.

Nematodes collected from the intestine of sompat grunt Pomadasys jubelini Cuvier, 1830 from Hann Bay in Dakar, Senegal represent a new species described herein as Dichelyne (Neocucullanellus) dakarensis n. sp., and investigated with the use of light and scanning electron microscopy. The new species differs from its congeners based on several characteristics, especially because the subgenus Neocucullanellus is the only 1 that has 2 ceca. In addition, the new species diagnosis is based on the number and arrangement of the caudal papillae as well as the size of the veil of spicules. Morphological data were supported by molecular analysis. Results obtained using SSU rDNA and COI distinguished the present specimens from other cucullanids. Molecular data indicated the close relatedness between the new species and Dichelyne cotylophora Ward and Magath, 1917.

REDESCRIPTION OF HASSALSTRONGYLUS ADUNCUS CHANDLER, 1932 (NEMATODA: HELIGMONELLIDAE), WITH THE DESCRIPTION OF A NEW SPECIES OF THE GENUS AND THEIR PHYLOGENETIC POSITION WITH OTHER HELIGMOSOMOIDEA TRAVASSOS, 1914.

ABSTRACT: Hassalstrongylus Durette-Desset, 1971 (Nematoda: Heligmonellidae), includes 19 species that are distributed from the southwestern United States to central-western Argentina. Hassalstrongylus aduncus is a parasitic nematode of rodents from the subfamilies Arvicolinae, Murinae, and Sigmodontinae, and has been recorded from southern Virginia and Oklahoma to Costa Rica. This species was described by Chandler in 1932; the morphology of the synlophe was not included. Subsequently, in 1972, Durette-Desset described only the synlophe of the middle region of the body in both sexes. Despite its wide geographical distribution, to date, there has been no redescription that includes information complementary to the morphology of the synlophe, such as a study of the body surface or a molecular phylogenetic analysis. We reevaluated the morphology of some specimens that were presumably similar to H. aduncus parasite of Sigmodon sp. from Jalisco, Mexico, and it was determined that these corresponded to an undescribed species of the genus. Herein, we present a redescription of H. aduncus parasite of Sigmodon toltecus from Hidalgo, Mexico, with morphological traits such as the excretory pore, deirids, and ovijector, and provide a description of the synlophe in the anterior and posterior regions of both sexes and include scanning electron microscopy images. Hassalstrongylus geolayarum n. sp. is differentiated from H. aduncus by the number of ridges in the middle region of the body (23 vs. 21), as well as proportions between some traits of males and females such as total length/spicule length, total length/gubernaculum length, total length/length of the esophagus and total length/distance of the vulva and the size of the eggs (42 vs. 58 µm). Phylogenetic analysis is based on partial sequences of the nuclear ribosomal internal transcribed spacer region (ITS1 + 5.8S + ITS2) of the rDNA, using the maximum-parsimony, maximum-likelihood, and Bayesian inference methods revealed the close relationship of H. aduncus + H. geolayarum n. sp. within the Heligmosomoidea and confirmed the placement of the Hassalstrongylus monophyletic clade well-supported within Heligmonellidae. The new species presented a genetic divergence of 3.4-3.8% relative to H. aduncus. This is the first species of the genus described in Mexico. Presumably, there are more species not yet described throughout the geographic range of H. aduncus. A taxonomic review and molecular phylogenetic analysis are required in which more species and genes are analyzed in Heligmosomoidea to confirm the status of the nonmonophyletic groups recovered here.

Analyzing the morphology and avian ß-defensins genes (AvßD) expression in the small intestine of Cobb500 broiler chicks fed with sodium butyrate.

BACKGROUND: Sodium butyrate is a potential antibiotic growth promoter and has had advantageous effects on the poultry industry. METHODS: Evaluating the effect of sodium butyrate on the intestinal villi and the humoral part of innate immunity of the male Cobb 500 broiler using scanning electron microscopy and quantitative real-time PCR analysis, the control group and treated group of Cobb 500 with SB supplemented received water containing 0.98 mg sodium butyrate. RESULTS: The administration of sodium butyrate changed the villi characters, as the shape changed from tongue to long tongue. They were mainly parallel to each other and long finger-like at the duodenum. The tips of the villi in the control group appeared thin-slight curved with a prominent center in the duodenum, thin rectangular in the jejunum, and ileum in the control group. In contrast, in the treatment group, they changed to thick rectangular in the duodenum and ileum zigzag shape in the jejunum. The epithelium lining of the duodenal villi showed a dome shape, the jejunal villi showed a polygonal shape, and the ileal villi appeared scales-like. The epithelium lining showed irregular microfolds and many different-sized pores, and the treatment group showed islands of long microvilli in the duodenum and solitary long microvilli in the ileum. Real-time PCR of AvBD 1, 2, 10, and 12 significantly (P < 0.01). The better expression of AvBD 1, 2, and 12 was determined in the duodenum, while AvBD 10 was in the jejunum. CONCLUSION: Sodium butyrate enhanced the chicks' growth and small intestine parameters, modified the morphology of the intestinal villi, and improved the humoral part of innate immunity.

Gross and scanning electron microscopic features of the oral cavity (palate, tongue, and sublingual floor) of the Egyptian long-eared hedgehog (Hemiechinus auratus aegyptius).

The study was focused on the anatomical characteristics of the Egyptian long-eared hedgehog's oral cavity by using gross and scanning electron microscopic examinations. The upper lip had an elongated T-shaped snout-like structure. The hard palate had a triangular rostral part (which had a semicircular area and a caudal ridged area with the first 3 or 4 ridges) and a caudal part (which contained seven or eight slightly oblique ridges with raphae). The diamond-incisive papilla is flanked on both sides by a groove and a fissure. The hard palate surface had glandular openings and a microplicae system. The uneven, soft palate's surface had multiple grooves and folds with 12-16 Gemmal papillae. The Gemmal papillary surface had three to four taste pores with microplicae and glandular openings. The dorsal lingual surface had six filiform subtypes: pointed (on the tip, rostral border, and median apical region), triangular (on the lateral apical and circumvallate regions), bifurcated (on the median tip only), leaf-like (on the median body region), branched (on the lateral root region), and small pointed papillae (on the median root). There were two fungiform subtypes: ovals (on the rostral border and lateral region) and rounds (on the median apical region and body). The caudal root part had a triangular arrangement of three circumvallate papillae. In conclusion, the finding confirmed its oral cavity adaptation with its insectivorous feeding habits and Egyptian environment.

Anatomical, histological, and scanning electron microscopic features of the esophagus and crop in young and adult domestic pigeons (Columba livia Domestica).

BACKGROUND: Pigeons (Columba livia) are mainly raised as a source of animal protein, racing, leisure and as an experimental animal. The present study investigated the morphology of the esophagus in the young and adult domestic pigeon, Columba livia domestica. METHODS: Ten young and ten adult, normal, and healthy pigeons were collected from the local breeders. Samples from different parts of esophagus and crop were examined grossly, by stereomicroscopy, scanning and light microscopy. RESULTS: The esophagus consisted of a long cervical part, a crop, and a short thoracic part. The crop was represented by a thin-walled outpouching with two lateral diverticula. The mucosa presented wavy fine folds in the cervical esophagus, irregular folds in the lateral diverticula giving it a corrugated appearance, and prominent longitudinal folds with several gland openings in the middle and lower parts of the crop, as well as in the thoracic esophagus. The density of gland openings was higher in adult pigeons than that in young pigeons. The mucosa of the esophagus was lined by non-keratinized stratified squamous epithelium. The shape, height, and branching of the mucosal folds differed between young and adult pigeons. Mucous-secreting alveoli were detected in the middle part of the crop as well as in the thoracic esophagus, but not in the cervical esophagus or lateral diverticula of the crop. CONCLUSION: The variations between the young and adult pigeons suggest a functional adaptation of adult pigeons to their diet compared to young pigeons.

Redescription of Raphidascaris (Ichthyascaris) vicentei (Nematoda: Raphidascarididae) Parasitizing Lutjanid Fishes (Actinopterygii: Lutjanidae) from the Northeast Coast of Brazil, Including First Observation Using SEM.

PURPOSE: In this study, 143 lutjanid fishes representing four different species from the Northeast coast off Brazil were analyzed for parasites. The aim of the present study is to provide a detailed redescription of R. (I.) vicentei, collected from lutjanid fishes in Brazil, including the first observation of the species using scanning electron microscopy (SEM). METHODS: Nematodes found clarified in a crescent glycerin series, were photographed and measured (in mm), and some specimens destined for SEM. The Illustrations were made using an optical microscope with a drawing tube. RESULTS: Nematodes found were identified as Raphidascaris (Ichthyascaris) vicentei, infecting 6.29% of the examined fish. Detailed morphological analysis revealed the following characteristics observed for the first time in this species: labial papillae, narrow lateral alae and the detailed structure of male spicules. These contributions help filling the gaps in the literature and expand the knowledge of this parasite morphology. CONCLUSIONS: The presence of R. (I.) vicentei in four lutjanid species may indicates low host specificity, highlighting its adaptability to different hosts. Furthermore, new host records are given. This research provides the most comprehensive morphological description of R. (I.) vicentei to date, generating crucial insights for a better understanding of the parasitic biodiversity off the Brazilian Northeastern coast of Brazil, as well as establishing foundation for future investigations on the ecology and impacts of these parasites in fish populations from this region.

Morphological and Molecular Analyses of Aponurus laguncula Looss, 1907 (Digenea: Lecithasteridae) Parasitic in Atlantic Spadefish Chaetodipterus faber (Broussonet, 1782) (Acanthuriformes: Ephippidae) from Brazilian Coastal Zone.

OBJECTIVES: An integrative taxonomic description of Aponurus laguncula (Lecithasteridae), a digenean parasitic species of Chaetodipterus faber (Acanthuriformes) from Brazilian Southeast, is provided. Morphological techniques, as whole mounted slides, histology and scanning electron microscopy, and molecular analyses supported that integrative description. METHODS: Fifteen digenean specimens were stained in hydrochloric carmine and mounted on permanent slides. Two specimens were stained in hematoxylin and eosin following histological routine processing. Four parasites were dehydrated through a graded ethanol series, critical point dried with carbon dioxide and coated with gold to scanning electron microscopy analysis. Sequence of the large ribosomal subunit (28S rDNA) gene was generated and used to construct a phylogeny based on maximum likelihood and Bayesian inference analyses. RESULTS: Morphological description and morphometric data obtained in present study were in accordance with previous studies of the species. Use of another morphological techniques, as scanning electron microscopy and histology, corroborated the observed features of whole mounted slides. Also, they provided a better observation of previous reported characteristics and new features reporting, such as an elongated hermaphroditic duct, a smooth tegument and cells that compose the prostatic gland. The molecular sequence obtained in the present study formed a robust clade with available sequences of species of Aponurus. CONCLUSIONS: The integrative taxonomic approach successfully combined morphological observations, including both previously reported features and new descriptions from histological and electron microscopy analyses, with molecular data to identify these specimens as A. laguncula. Moreover, the detailed characterization of structures, such as the gonads in A. laguncula, that would be challenging to analyze using a single technique, was possible. Further molecular studies with less conserved genetic markers should be conducted to understand phylogenetic relationships between Aponurus species.

DESCRIPTIONS AND PHYLOGENETIC AFFINITIES OF TWO NEW SPECIES OF RHABDIAS STILES AND HASSALL, 1905 (NEMATODA: RHABDIASIDAE) FROM NORTH AMERICAN FROGS: ARE WE STILL ONLY SCRATCHING THE SURFACE?

Two new species of lung-dwelling nematodes are described from North American frogs: Rhabdias aurorae n. sp. from Rana aurora and Rhabdias conni n. sp. from Rana clamitans and Rana catesbeiana from Arkansas; the latter species was also found in Oklahoma and Georgia. Rhabdias aurorae n. sp. differs from other Nearctic congeners in the combination of the following characteristics: buccal capsule 22-25 µm wide, elongated tail covered with inflated cuticle, esophagus with prominent dilatation in anterior part and 6 small circumoral lips. Rhabdias conni n. sp. is morphologically closest to Rhabdias ranae Walton, 1929 and Rhabdias joaquinensisIngles, 1936; it differs from them in the shape of lateral pseudolabia, the dimensions of the body, and the egg size. Both new species were found to be significantly different from the Nearctic congeners in the nucleotide sequences of nuclear ribosomal DNA (18S-ITS-28S region), 12S, and CO1 mitochondrial genes. The 2 new species differ from other currently sequenced Nearctic congeners by 1.1-2.7% of nucleotide positions in the nuclear rDNA region, 1.3-3.4% in the 12S gene, and 3.4-9.4% in CO1 gene. Molecular phylogenetic analysis based on nuclear ribosomal DNA sequences placed both new species into the clade consisting of Nearctic and Neotropical Rhabdias spp. The position of Rh. aurorae n. sp. within the clade is uncertain because of a polytomy, but Rh. conni n. sp. is nested within the "Rh. joaquinensis complex" related to Rh. ranae and Rhabdias tarichaeKuzmin, Tkach, and Snyder, 2003. The phylogenetic analysis based on nuclear ribosomal DNA sequences has revealed 3 evolutionary host-switching events from anuran to caudatan hosts among Rhabdias spp. that occurred in the Nearctic and Palearctic. The molecular phylogeny also suggests that Rhabdias may have originally evolved in what is now Africa.

Morphology, complete mitochondrial genome, and molecular phylogeny of Rhabdias macrocephalum n. sp. (Nematoda: Rhabdiasidae) from Diploderma splendidum (Reptilia: Agamidae).

Species of the genus Rhabdias Stiles & Hassall, 1905 are common parasitic nematodes occurring in the lungs of amphibians and reptiles worldwide. In the present study, Rhabdias macrocephalum n. sp. is described using integrated morphological methods (light and scanning electron microscopy) and molecular approaches (sequencing of the nuclear 28S and ITS regions, and mitochondrial cox1, cox2, and 12S genes) based on specimens collected from the green striped tree dragon Diploderma splendidum (Barbour & Dunn) (Reptilia: Agamidae) in China. The complete mitochondrial genome of R. macrocephalum n. sp. was sequenced and annotated: it is 14,819 bp in length, including 12 protein coding genes (missing atp8), 22 tRNA genes, 2 rRNA genes and three non-coding regions. The gene arrangement of R. macrocephalum n. sp. is different from all of the currently available mitogenomes of nematodes and represents a novel type of mitochondrial gene arrangement reported in Nematoda. Molecular phylogenetic results based on the ITS + 28S data support the monophyly of Entomelas, Pneumonema, Serpentirhabdias, and Rhabdias, and showed R. macrocephalum n. sp. forming a most basal lineage in Rhabdias.

Title: Morphologie, génome mitochondrial complet et phylogénie moléculaire de Rhabdias macrocephalum n. sp. (Nematoda : Rhabdiasidae) de Diploderma splendidum (Reptilia : Agamidae). Abstract: Les espèces du genre Rhabdias Stiles & Hassall, 1905 sont des nématodes parasites courants présents dans les poumons des amphibiens et des reptiles du monde entier. Dans cette étude, Rhabdias macrocephalum n. sp. est décrit à l'aide de méthodes morphologiques intégrées (microscopie optique et électronique à balayage) et d'approches moléculaires (séquençage des régions nucléaires 28S et ITS et des gènes mitochondriaux cox1, cox2 et 12S) basées sur des spécimens collectés chez le lézard Diploderma splendidum (Barbour & Dunn) (Reptilia : Agamidae) de Chine. Le génome mitochondrial complet de R. macrocephalum n. sp. a été séquencé et annoté : il a une longueur de 14 819 pb, dont 12 gènes codants pour des protéines (atp8 manquant), 22 gènes d'ARNt, 2 gènes d'ARNr et trois régions non codantes. L'arrangement génétique de R. macrocephalum n. sp. est différent de tous les mitogénomes de nématodes actuellement disponibles et représente un nouveau type d'arrangement de gènes mitochondriaux signalé chez les nématodes. Les résultats phylogénétiques moléculaires basés sur les données ITS + 28S ont soutenu la monophylie d'Entomelas, Pneumonema, Serpentirhabdias et Rhabdias, et ont montré que R. macrocephalum n. sp. forme la lignée la plus basale chez Rhabdias.

Paronatrema davidbowiei n. sp. (Trematoda: Syncoeliidae), a new parasite of the pelagic thresher (Alopias pelagicus) and its phylogenetic relationships within the suborder Hemiurata Skrjabin & Guschanskaja, 1954.

A new species of hemiurid trematode found on the gills and in the aorta of the pelagic thresher Alopias pelagicus from the eastern Pacific, off Costa Rica, is described based on an integrative taxonomic approach that includes the use of light and scanning electron microscopy, and 28S rDNA sequencing. Phylogenetic analysis was also performed to explore, for the first time, the relationships of a member of the subfamily Otiotrematinae within the suborder Hemiurata. Paronatrema davidbowiei n. sp. can be distinguished from the congeners by having tegumental spines on the dorsal surface of the forebody, papillae on the oral sucker, and different morphology or number of testicular follicles. BLAST analysis revealed that sequences of Paronatrema davidbowiei n. sp. had the highest degree of similarity with Hirudinella spp. (Hirudinellidae). Results from Maximum Likelihood and Bayesian phylogenetic analyses, returning trees with the exact same topology and strong branch support, distinguished between the two superfamilies included in the suborder Hemiurata: Azygioidea and Hemiuroidea. Our analysis placed the new species in a clade with Copiatestes filiferus, the only existing sequence of the family Syncoeliidae.

Macro- and micro-anatomical investigation of the oropharyngeal roof of landform greek tortoise (Testudo graeca graeca) and semi-aquatic red-eared slider turtle (Trachemys scripta elegans).

The present investigation examined the oropharyngeal roof of two turtles having different feeding behaviors: the landform Greek tortoise (Testudo graeca graeca) primarily herbivores and the semi-aquatic red-eared slider turtle (Trachemys scripta elegans) lives in freshwater that opportunistic omnivorous grossly and by scanning and light microscopes. Grossly, the Greek tortoise had a V-shaped roof consisting of the upper rhamphotheca, peri-palatine region, upper alveolar ridge, peripheral palatine ridge, median palatine ridge, vomer, choanae, caudal palatine part, and pharynx. At the same time, the red-eared slider had a semilunar roof consisting of upper rhamphotheca, two peripheral palatine ridges, core of palatine ridges, upper alveolar band, vomer, choanae, caudal palatine part, and pharynx. SEM revealed that the red-eared slider roof appeared more straightforward. The upper rhamphotheca is sharp, with a median premaxillary notch in the red-eared slider that gives a powerful bite for cutting to compensate absence of the teeth. Additionally, the red-eared slider's upper alveolar band is interrupted by a single upper alveolar ridge that appears spiky, pointed, and longer as it needs powerful chewing of prey and there are two types of teeth-like projections at its peri-palatine area for food-crushing and chewing. The Greek tortoise palatine region had numerous ridges and folds to provide roughness for food processing. Greek tortoises had small-sized choanae with two choanal folds to minimize choanal openings when eating dusty grasses. Histologically, Greek tortoise palate was rostrally thicker and more keratinized than caudally, and the caudal palatine region was characterized by a single pair of circumvallate-like papilla with multiple mucous openings and secretions, while red-eared slider palate was slightly keratinized at the peri-choanal region, and the rest of the palate was non-keratinized with few mucous openings. The current investigation found various structural oropharyngeal roof adaptations to feeding behavior in the omnivore red-eared slide compared to the herbivorous Greek turtle.

Toxicity of 6-gingerol and Cymbopogon citratus against Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae): Mortality, detoxifying enzymes, and morphological ultrastructure alterations in lice.

Pediculus humanus capitis (head louse), which causes pediculosis capitis, remains a global health concern. Plant products are efficient alternative pediculicides for treating the human ectoparasite P. h. capitis which is resistant to permethrin. The study evaluates the toxicity and mechanisms of 6-gingerol and Cymbopogon citratus leaf extract on P. h. capitis. Pediculus humanus capitis adult stages were exposed to three different dosages of 6-gingerol and C. citratus crude leaf extract on filter sheets for 5, 10, and 30 min, respectively. The biochemical approach was used to assess the activity of detoxifying enzymes including acetylcholinesterase (AChE), glutathione S-transferase (GST), and oxidase. Scanning electron microscope (SEM) was used to investigate the ultrastructure of the morphological body of lice. After 30 min, 6-gingerol and C. citratus leaf extract killed P. h. capitis completely. Bioassay periods significantly affected lice mortality (P < 0.05). The LC50 values for 6-gingerol and C. citratus extract were 1.79 µg/cm2 and 25.0 µg/cm2, respectively. 6-Gingerol and C. citratus leaf extract significantly lower AChE and GST activity (P < 0.05). Cymbopogon citratus also caused morphological ultrastructure changes in P. h. capitis, including an irregularly formed head, thorax, abdominal respiratory spiracles, and belly. 6-Gingerol and C. citratus leaf extracts could be used as an alternate pediculicide to decrease P. h. capitis populations.

Characterization of ß-glucan obtained from Candida albicans of caprine mastitis.

Background: Beta-glucan (ß-glucan) is a polysaccharide containing ß-glycosidic bonds that is an important structure part of different yeast cells. Aim: The purpose of the study is to characterize ß-glucan obtained from Candida albicans (C. albicans) isolated from caprine mastitis. Methods: The ß-glucan was extracted by using utilizing an Alkaline-acidic extraction technique. The dry weight of extracted ß-glucan was 7.47/150 g with 4.98%. Results: The findings demonstrated that the extracted ß-glucan had similarity in the primary peak 5.78 of liquid samples using the method of high-performance liquid chromatography when compared to the standard form of ß-glucan. However, scanning electron microscopy studies revealed that the standard of ß-glucan was distinct in morphology but similar to ß-glucan isolated from C. albicans in terms of particle sizes in the range of 1.60-2.65 m and the lack of cell wall traces. The findings of an investigation using energy-dispersive X-ray fluorescence spectroscopy (EDS/EDX) of extracted and standard ß-glucan, showed the principal elements discovered were carbon (C), oxygen (O), and nitrogen (N). Aluminum (Al), silicon (Si), nickel (Ni), and gold (Au) were also present, but in less amounts. Conclusion: The extracted ß-glucan displayed a high degree of similarity and purity to the standard ß-glucan, according to the findings of Fourier transform infrared spectroscopy (FT-IR) research.

Histology, histochemistry and ultrastructure of cornea of domestic pigs (Sus scrofa domesticus).

A comprehensive light and ultrastructural examination of the cornea in Domestic Pigs (Sus scrofa domesticus) revealed four distinct layers: the anterior epithelium, corneal stroma, Descemet's membrane and endothelium. Although Bowman's layer was not distinctly identified through histology, histochemical analysis indicated the presence of a rudimentary Bowman's layer, possibly vestigial from evolution. Scanning electron microscopy of the outer corneal surface unveiled two cell types, characterized by micro-projections, with light cells exhibiting shorter, thicker projections compared to dark cells. Examination of the inner surface via scanning electron microscopy demonstrated an endothelial layer devoid of cilia and microvilli, yet faint round to oval elevations were observed, potentially representing cell nuclei. Transmission electron microscopy unveiled that basal cells of the anterior epithelium closely adhered to the basement membrane, featuring half desmosomes along the basal surface. These basal cells extensively interconnected through interdigitations and a few desmosomes. The superficial cell layer consisted of a few rows of closely attached flat cells, forming a leak-proof layer with zona occludens. The outermost cells of this layer displayed fine projections to enhance the surface area, facilitating tear film distribution. At lower magnification, Transmission electron microscopy of the corneal stroma revealed alternating light and dark bands, with light bands representing transverse sections of collagen fibril lamellae and dark bands corresponding to longitudinal or oblique sections. Spindle-shaped keratocytes (fibroblasts) were identified as the primary stromal cells, intermingled between the lamellae, and featured long processes in close contact with neighbouring keratocytes. Overall, the histomorphology of the pig cornea resembles that of the human cornea except indistinct Bowman's membrane. This detailed understanding of the normal corneal structure in pigs hold great significance for biomedical research, providing a valuable reference for studies involving this animal model.

Comparative macroanatomical and scanning electron microscopy study of the eyeball in brachycephalic and mesocephalic dog breeds.

The anatomical structures forming the eyeball differ among dog breeds, both morphologically and morphometrically. This study was aimed at determining the morphometric values of the eyeball layers of different dog breeds and the morphological structures of these layers using scanning electron microscopy. Thirty-two eyeballs of 17 dogs belonging to 9 different breeds that died from traffic accidents, falling from a height, and naturally were used. These dog breeds were grouped according to their brachycephalic and mesocephalic skull structures, and morphometric measurements of the eyeballs of each group were obtained. Scanning electron microscopy was used to examine the morphological structure of the eyeball layers. The studied dogs' eyeballs comprised three layers: outer, middle, and inner. Thickness measurements obtained from three different regions of the eyeball indicated that the equatorial region was the thinnest among all dog breeds. Moreover, the cornea, which is covered by the sclera along its edges, was thicker at the corneal limbus than at the corneal vertex. A positive correlation was observed between lens thickness and the number of ciliary processes, which varied according to the dogs' head structures. Notably, depression was observed in the posterior surface of the lens in brachycephalic dogs. The morphometric values of the eyeball layers in the brachycephalic and mesocephalic dog breeds were also determined. These values will help researchers study this subject, and the determined morphometric and morphological values will contribute to the anatomy literature. RESEARCH HIGHLIGHTS: This comprehensive study investigates the morphometric and morphological variations in the eyeball layers of different dog breeds, utilizing scanning electron microscopy to analyze eyeballs. It reveals significant breed-specific differences, particularly between brachycephalic and mesocephalic dogs, regarding eyeball layer thickness, corneal structure, lens thickness, and the number of ciliary processes.

Examination of upper respiratory tracts of Siirt-coloured mohair goats by scanning electron microscopy before and after plastination.

Present study was conducted to determine the changes in the surface structure of the upper respiratory tract of Siirt-coloured mohair goats by the silicone plastination method. Accordingly, the heads of 10 Siirt-coloured mohair goats procured from slaughterhouses were divided into two halves. Half of each head was plastinated. After macro-comparisons were made, the deformations of silicone plastination on the surface were examined by comparing the scanning electron microscope (SEM) findings of both upper respiratory tract tissue samples collected from plastinates and fresh material. When the data from scanning electron microscopy were analysed, cilia, cobblestone patterns, goblet cells and gland ducts on the epithelial surface were identified in areas on the upper respiratory tract. The SEM images of the plastinated tissues showed that the surface structures were degenerated due to the deformation of the surface epithelium. The plastination technique damaged the structures on the surface epithelium. Since the plastination technique and scanning electron microscopy have been studied together for the first time, we believe this would contribute to the scientific literature.

MOLECULAR PHYLOGENY OF THE LEECH GENUS PONTOBDELLA (HIRUDINIDA: PISCICOLIDAE) WITH NOTES ON PONTOBDELLA CALIFORNIANA AND PONTOBDELLA MACROTHELA.

Leech specimens of the genus Pontobdella (Hirudinida: Piscicolidae) were found off the coast of the state of Oaxaca (Pacific) as well as in Veracruz and Tabasco (Gulf of Mexico), Mexico. Based on the specimens collected in Oaxaca, a redescription of Pontobdella californiana is provided, with emphasis on the differences in the reproductive organs with the original description of the species. In addition, leech cocoons assigned to P. californiana were found attached to items hauled by gillnets and studied using scanning electron microscopy and molecular approaches. Samples of Pontobdella macrothela were found in both Pacific and Atlantic oceans, representing new geographic records. The phylogenetic position of P. californiana is investigated for the first time, and with the addition of Mexican samples of both species, the phylogenetic relationships within Pontobdella are reinvestigated. Parsimony and maximum-likelihood phylogenetic analysis were based on mitochondrial (cytochrome oxidase subunit I [COI] and 12S rRNA) and nuclear (18S rRNA and 28S rRNA) DNA sequences. Based on our results, we confirm the monophyly of Pontobdella and the pantropical distribution of P. macrothela with a new record in the Tropical Eastern Pacific.

Embryonic development of the scorpion mud turtle (Kinosternon scorpioides) bred in captivity.

Background: The developmental biology of Kinosternon scorpioides is described, based on the phenotype. This species is important for the flora because they are excellent seed disseminators. In addition, basic embryological information is not yet fully clarified, and this research provides unprecedented information on the chelonian embryology of the Amazonian fauna. Aim: The present study aims to identify the embryology of K. scorpioides in captivity during different periods. Methods: Females were monitored throughout the reproductive cycle, by video monitoring, to identify nests and the presence of newly laid eggs. At regular weekly intervals, embryo samples were collected fixed in a 4% paraformol solution and preserved in 70% alcohol. For the embryonic characterization, we used a stereomicroscope and the scanning electron microscopy method. Results: We describe 15 embryonic stages for a 15-week (105-day) incubation process. Only at 42 days (6th week) was the morphological characterization of a chelonian observed and at the 12th week (Stage XII), the phenotypic characterization of the species K. scorpioides. Conclusion: In view of the evidence, we found that these phases are similar to the other turtles, with structural variations in the appearance and disappearance of structures due to the specific characteristics of the species.

Ultramicroscopic organization of the exterior olfactory organ in Anguilla vulgaris in relation to its spawning migration.

Background: Catadromous fishes have well-developed elongated olfactory organs with numerous lamellae and different types of receptor neurons related to their breeding migration. Aim: The current study showed how the olfactory system adapted to the catadromous life. Our work declared the need of the migratory fishes for the sense of smell that is exhibited by a higher number of the olfactory lamellae and the receptor neuron verification in the olfactory epithelium. Methods: Ten specimens of fully grown, but pre-matured, silver eels of Anguilla vulgaris were captured at the outlet of Edco Lake, overlooking the Mediterranean Sea, east of Alexandria. Olfactory rosettes were dissected and fixed for scanning electron microscope (SEM) and transmission electron microscope (TEM). Results: Our study gave a morphological description of the olfactory system of A. vulgaris. At the ultrastructural level using SEM and TEM, one olfactory rosette was provided with 90-100 flat radial olfactory lamellae. The nasal configuration allowed water to enter and exit, transferring odorant molecules to olfactory receptor cells which comprise long cylindrical ciliated and microvillous receptors as well as rod-tipped cells. These cells are bipolar neurons with upward dendritic knobs. The olfactory epithelia also include crypt receptor cells. Interestingly, the olfactory neurons are delimited by nonsensory supporting cells, including long motile kinocilia and sustentacular supporting cells beside mucus secretory goblet cells and ionocytes or labyrinth cells that contribute to the olfaction process. Conclusion: Olfaction is crucial in all vertebrates, including fishes as it involves reproduction, parental, feeding, defensive, schooling, and migration behaviors. Here, A. vulgaris is an excellent model for catadromous fishes. It has a well-developed olfactory organ to cope with the dramatic climate change, habitat loss, water pollution, and altered ocean currents effect during their catadromous life for reproduction.

Paracapillaria (Ophidiocapillaria) siamensis sp. nov. (Nematoda: Trichuroidea): a new nematode in Naja kaouthia from Thailand.

A comprehensive investigation, incorporating both morphological and molecular analyses, has unveiled the existence of a hitherto unknown nematode species, Paracapillaria (Ophidiocapillaria) siamensis sp. nov., residing in the intestine of the monocled cobra, Naja kaouthia, in the central region of Thailand. This study integrates morphological characteristics, morphometric examination, scanning electron microscopy and molecular phylogenetic analysis (COI, 18S rRNA and ITS1 genes). The findings place the newly described species within the subgenus Ophidiocapillaria, elucidating its distinctive characteristics, including a frame-like proximal spicule shape, approximate lengths of 19 000 and 22 500 µm with approximate widths of 90 and 130 µm for males and females, 39‒45 stichocytes, elevated lips without protrusion, a dorsal bacillary band stripe with an irregular pattern of bacillary cells and evidence of intestinal infection. These features serve to differentiate it from other species within the same subgenus, notably Paracapillaria (Ophidiocapillaria) najae De, , a species coexisting P. siamensis sp. nov. in the monocled cobra from the same locality. This study addresses the co-infection of the novel species and P. najae within the same snake host, marking the second documented instance of a paracapillariid species in the monocled cobra within the family Elapidae. The genetic characterization supports the formal recognition of P. siamensis sp. nov. as a distinct species, thereby underscoring its taxonomic differentiation within the Capillariidae family. This research identifies and characterizes the new nematode species, contributing valuable insights into the taxonomy of this nematode.