The usefulness of dermoscopy in canine pattern alopecia: a descriptive study.

BACKGROUND: Dermoscopic studies evaluating noninflammatory, nonpruritic progressive alopecia attributable to pattern alopecia are currently unavailable. HYPOTHESIS/OBJECTIVES: To evaluate the dermoscopic features observed in healthy skin of short coated dogs and compare these findings with those observed in dogs affected by pattern alopecia diagnosed by clinical and dermatopathological examination. ANIMALS: Thirty male and female, healthy, breed matched, young adult, short coated dogs (controls) and 30 male and female, young adult, short coated dogs affected by pattern alopecia. METHODS: Dermoscopy was performed with a Fotofinder II videodermoscope equipped with software that allowed the measurement of structures visualized in magnified images (20×-40×-70×). Skin biopsy samples were obtained from the thorax and evaluated dermoscopically for dermoscopic-histological correlation in affected dogs. RESULTS: Dermoscopic findings in canine pattern alopecia were hair shaft thinning, circle hairs and follicular keratin plugs; in the affected sun exposed areas there was a honeycomb-like pattern of pigmentation. Arborizing red lines reflecting vascularization were classified as a nonspecific finding because they were also common in healthy dogs. Dermoscopic features correlated with histology for selected hair follicle abnormalities. CONCLUSIONS AND CLINICAL IMPORTANCE: Although canine pattern alopecia is a visually striking disease, this study supports the value of dermoscopy for clinical examination and also opens promising perspectives for the identification of diagnostic dermoscopic patterns that may be useful for other skin disorders.

Dermoscopic evaluation of skin in healthy cats.

BACKGROUND: Dermoscopy is a diagnostic tool that can reveal morphological structures not visible upon clinical examination. HYPOTHESIS/OBJECTIVES: To assess the usefulness and applicability of dermoscopy for the examination of healthy cat skin. ANIMALS: Twenty-one domestic short-haired cats from a feline rescue association. METHODS: Four regions (head, dorsal neck, sacral and abdominal regions) were examined with both a contact hand-held nonpolarized light dermoscope at 10-fold magnification and a videodermoscope at 70-fold magnification. Findings were assessed using histological analysis of skin samples cut both longitudinally and transversely, set as the gold standard. RESULTS: With a hand-held dermoscope at 10-fold magnification, thick, straight primary hairs surrounded by multiple secondary hairs were observed. With a videodermoscope at 70-fold magnification, hair shaft thickness was measured and the follicular openings and arrangement of vessels were clearly observed. Correspondence was observed between dermoscopic and histological results. CONCLUSIONS AND CLINICAL IMPORTANCE: Dermoscopy represents a valid noninvasive and reproducible technique that could be helpful in clinical examination.

Follicular fluid leptin concentrations and expression of leptin and leptin receptor in the equine ovary and in vitro-matured oocyte with reference to pubertal development and breeds.

There is no published information about follicular-fluid leptin concentrations or the presence of leptin and leptin receptor in the equine ovary or oocyte. Three groups of mares - adult draft mares, draft fillies and adult Standardbred mares - were included in the study. Leptin and leptin receptor were detected in all immature oocytes by immunofluorescence with higher intensity in oocytes from draft mares compared with draft fillies and Standardbred mares. After in vitro maturation a higher proportion of oocytes reached metaphase II in draft mares than in draft fillies and Standardbred mares, and in all groups both leptin and leptin receptor became localised in the oocyte cortex but with higher immunopositivity in draft mares compared with draft fillies and Standardbred mares. These intensities were confirmed by the expression profiles of leptin and leptin receptor mRNA. Moreover, leptin was detected in ovarian blood vessels in all three types of animal and within the corpora lutea in adult mares. Serum and follicular-fluid concentrations of leptin were similar in draft and Standardbred mares but higher in draft mares than in draft fillies. This study supports the hypothesis that expression of leptin and leptin receptor mRNA and the rate of maturation can be related either to adiposity or to puberty.

Effects of leptin on in vitro maturation, fertilization and embryonic cleavage after ICSI and early developmental expression of leptin (Ob) and leptin receptor (ObR) proteins in the horse.

BACKGROUND: The identification of the adipocyte-derived obesity gene product, leptin (Ob), and subsequently its association with reproduction in rodents and humans led to speculations that leptin may be involved in the regulation of oocyte and preimplantation embryo development. In mice and pigs, in vitro leptin addition significantly increased meiotic resumption and promoted preimplantation embryo development in a dose-dependent manner. This study was conducted to determine whether leptin supplementation during in vitro maturation (IVM) to horse oocytes could have effects on their developmental capacity after fertilization by IntraCytoplasmic Sperm Injection (ICSI). METHODS: Compact and expanded-cumulus horse oocytes were matured in medium containing different concentrations (1, 10, 100, 1000 ng/ml) of recombinant human leptin and the effects on maturation, fertilization and embryo cleavage were evaluated. Furthermore, early developmental expression of Ob and leptin receptor (Ob-R) was investigated by immunocytochemical staining. RESULTS: In expanded-cumulus oocytes, the addition of leptin in IVM medium improved maturation (74% vs 44%, for 100 ng/ml leptin-treated and control groups, respectively; P < 0.05) and fertilization after ICSI (56% vs 23% for 10 ng/ml leptin-treated and control groups, respectively; P < 0.05). However, the developmental rate and quality of 8-cell stage embryos derived from leptin-treated oocytes (100 ng/ml) was significantly reduced, in contrast to previous data in other species where leptin increased embryo cleavage. Ob and Ob-R proteins were detected up to the 8-cell stage with cortical and cytoplasmic granule-like distribution pattern in each blastomere. CONCLUSION: Leptin plays a cumulus cell-mediated role in the regulation of oocyte maturation in the mare. Species-specific differences may exist in oocyte sensitivity to leptin.

Persistent Müllerian Duct Syndrome in a German Shepherd Dog.

In mammals, the regression of the müllerian ducts is regulated by the action of the AMH hormone which is produced by testes during embryonic development. The action of this hormone is mediated by the only known receptor AMHR2. Mutations occurring in the AHM hormone and/or in the AMHR2 receptor gene cause the lack of regression of müllerian ducts, which may therefore persist even in male embryos carrying a XY chromosomal arrangement. This is known as the persistent müllerian duct syndrome (PMDS). A female German Shepherd dog was referred to the veterinary clinic because of urinary incontinence. She also showed an anatomical structure that protruded from and enlarged the vulvar labia. From the morphological appearance, one gonad resembled an ovary and the other a testicle. The histological examination instead showed that the gonads were both testes with an underdeveloped parenchyma and without signs of spermatogenetic activity. No alterations were found with regard to the uterus which showed a correctly developed body, cervix, and horns. Genetic analysis, performed on DNA extracted from blood, showed (i) the presence of both X and Y chromosomes, (ii) the absence of chromosome XX/XY chimerism, (iii) a normal SRY gene coding sequence, (iv) a normal AMHR2 gene coding sequence, and (v) a normal AMH gene coding sequence. In this study, we report and characterize a new case of PMDS in a dog excluding that the only mutation hitherto found in the AMHR2 gene is responsible for the observed phenotype.

XY (SRY-positive) Ovarian Disorder of Sex Development in Cattle.

In mammals, the sex of the embryo depends on the SRY gene. In the presence of at least one intact and functional copy of this genetic factor (XY embryo) undifferentiated gonads will develop as testicles that subsequently determine the male phenotype. When this factor is not present, i.e., in subjects with 2 X chromosomes, an alternative pathway induces the development of ovaries, hence a female phenotype. In this case study, we describe a female cattle affected by a disorder of sex development (DSD). The subject, despite having a chromosomal XY constitution, did not develop testicles but ovaries, although they were underdeveloped. Moreover, genetic analysis highlighted the presence of the SRY gene with a normal coding region in both blood- and tissue-derived DNA. A chimeric condition was excluded in blood by sexing more than 350 cells and by allele profile investigation of 18 microsatellite markers. Array CGH analysis showed the presence of a not yet described 99-kb duplication (BTA18), but its relationship with the phenotype remains to be demonstrated. Gonadal histology demonstrated paired ovaries: the left one containing a large corpus luteum and the right one showing an underdeveloped aspect and very few early follicles. To our knowledge, we describe the first case of XY (SRY+) DSD in cattle with a normal SRY gene coding sequence.

Ultrasonography as a complementary diagnostic method for evaluating the skin of healthy cats.

Ultrasonography is not often used in feline dermatology. The purpose of this study was to assess the usefulness and applicability of ultrasonography for skin evaluation in 21 clinically healthy cats. Ultrasonographic examination was conducted in 4 cutaneous regions (frontal, dorsal neck, sacral, and abdominal) using an 18-MHz linear-sequential-array transducer. Findings were assessed using histomorphometric analysis of skin samples set as reference standards. Morphologic evaluation, thickness measurements, measurement variability, and comparison between regions and genders were carried out. The ultrasonographic pattern of feline skin was characterized by 3 distinct layers of different echogenicity and echostructure. Skin was thickest at the dorsal neck region and thinnest at the abdominal region. Skin at the frontal region and dorsal neck region was thicker in males. Variability was < 10% in all regions. No apparent correspondence was found between ultrasonographic and histometric measurements of skin thickness. Collectively, these findings suggest that ultrasonography is a simple, noninvasive, and reproducible technique that allows cutaneous layers to be identified and accurately measures skin thickness in cats.

L'échographie en dermatologie féline est actuellement peu utilisée. L'objectif de ce travail était d'estimer l'utilité et l'applicabilité de l'échographie pour l'évaluation de la peau chez 21 chats cliniquement sains. L'examen échographique a été effectué sur 4 régions cutanées (frontale, dorsale du cou, sacrée et abdominale) avec une sonde linéaire de 18 MHz. Les résultats ont été évalués en utilisant une analyse histomorphométrique établie comme référence standard. L'évaluation morphologique, les mesures d'épaisseur, la variabilité des mesures et la comparaison entre les régions et les sexes ont été effectuées. Le pattern échographique de la peau féline a été caractérisé par 3 couches distinctes pour échogénicité et échostructure différentes. La région dorsale du cou était la plus épaisse et l'abdominale la plus fine. Les régions frontale et dorsale du cou étaient plus épaisses chez le mâle. La variabilité était < 10 % en toutes les régions. Aucune correspondance apparente n'a été trouvée entre les mesures échographiques et histométrique. En général, ces résultats suggèrent que l'échographie représente une technique simple non invasive et reproductible, permettant d'identifier les couches cutanées et de mesurer l'épaisseur de la peau avec précision aussi chez les chats.(Traduit par les auteurs).

Histochemical analysis of glycoconjugate secretion in the alimentary canal of Anguilla anguilla L.

Conventional histochemical methods as well as lectin-binding techniques were used to study glycoconjugates that are present in the alimentary canal of the European eel (Anguilla anguilla). Specimens from pharynx, oesophagus, stomach and intestine were collected from adult ("silver eel" stage) females. Alcian Blue pH 2.5/PAS and High Iron Diamine/Alcian Blue pH 2.5 reactions were performed to stain neutral and acidic glycoconjugates. In addition, lectin histochemistry was applied to identify acidic glycoconjugates containing O-acylated sialic acids. Finally, the presence of sugar residues in the oligosaccharide side chains of glycoconjugates were investigated by using biotinylated lectins. Acidic and neutral glycoconjugates were found to be secreted throughout the alimentary canal, the acidic glycoconjugates appeared to be either sialylated or sulphated. Sialylated glycoconjugates were identified to contain sialic acid substituted at carbon in position 7 (C7). Sulphated glycoconjugates were particularly abundant in the distal intestine and were not present in the secretory products of the gastric mucosa, which contained a variety of sugar residues (D-N-acetyl-galactosamine, beta-D-galactose, alpha-D-mannose, alpha-L-fucose, D-N-acetyl-glucosamine). Lectin binding was observed in mucous cells of pharynx, oesophagus and intestine, and particularly some monosaccharides (D-N-acetyl-galactosamine and beta-D-galactose) were abundantly present.

The anatomy of the dog soft palate. III. Histological evaluation of the caudal soft palate in brachycephalic neonates.

A thickened and abnormally long soft palate is mostly involved in the pathogenesis of both nasopharyngeal and oropharyngeal narrowing, affecting the respiratory activity in virtually all of the brachycephalic dogs suffering from Brachycephalic Airway Obstructive Syndrome (BAOS). The morphology of the soft palate in adult mesaticephalic and brachycephalic dogs has been previously described. In this article specimens from brachycephalic dog neonates (N=10) dead from one to 3 hr after birth of unrelated conditions were collected and histologically evaluated at three transverse levels to describe the microscopic aspect of the caudal part of the soft palate. The soft palate of neonate brachycephalic dogs was histologically characterized by a musculo-connective axis containing salivary glands and coated by a mucosal layer on both the nasopharyngeal and the oral side. Quali-quantitative features, such as thickened superficial epithelium, broad oedema of the lamina propria, mucous gland hyperplasia and diverse muscular modifications described in adult brachycephalic dogs, were not observed in the soft palate of brachycephalic neonate dogs. The lack of tissue lesions in the soft palate of newborn brachycephalic dogs further supports the hypothesis that inspiratory depression during the inspiratory phase causes chronic vibration and microtrauma, which lead to soft palate alterations in adult brachycephalic dogs starting from the earliest grade of the respiratory syndrome. Overall, this study provides baseline information for the comprehension of the pathogenesis of BAOS.

Peculiarity of Porcine Amniotic Membrane and Its Derived Cells: A Contribution to the Study of Cell Therapy from a Large Animal Model.

The aim of this work was to provide, for the first time, a protocol for isolation and characterization of stem cells from porcine amniotic membrane in view of their potential uses in regenerative medicine. From three samples of allanto-amnion recovered at delivery, the amniotic membrane was stripped from overlying allantois and digested with trypsin and collagenase to isolate epithelial (amniotic epithelial cells [AECs]) and mesenchymal cells, respectively. Proliferation, differentiation, and characterization studies by molecular biology and flow cytometry were performed. Histological examination revealed very few mesenchymal cells in the stromal layer, and a cellular yield of AECs of 10 × 10(6)/gram of digested tissue was achieved. AECs readily attached to plastic culture dishes displaying typical cuboidal morphology and, although their proliferative capacity decreased to the fifth passage, AECs showed a mean doubling time of 24.77 ± 6 h and a mean frequency of one fibroblast colony-forming unit (CFU-F) for every 116.75 plated cells. AECs expressed mesenchymal stem cell (MSC) mRNA markers (CD29, CD166, CD90, CD73, CD117) and pluripotent markers (Nanog and Oct 4), whereas they were negative for CD34 and MHCII. Mesodermic, ectodermic, and endodermic differentiation was confirmed by staining and expression of specific markers. We conclude that porcine amniotic membrane can provide an attractive source of stem cells that may be a useful tool for biomedical research.

Primary cilia in the basal cells of equine epididymis: a serendipitous finding.

Occurrence of a solitary cilium was an unexpected discovery while studying the ultrastructure of epididymal epithelium in equidae. Primary cilia were detected in epididymal basal cells of all individuals of the equines studied - horses, donkey and mules - independently from age and tract of the duct, emerging from the basal cell surface and insinuating into the intercellular spaces. More rarely solitary cilia occurred also at the luminal surface of the principal cells. The ciliary apparatus was constituted by a structurally typical basal body continuous with the finger-like ciliary shaft extending from the cell surface, and an adjacent centriole oriented at right angles to the basal body. The cilium was structured as the typical primary, non-motile cilia found in many mammalian cells, having a 9+0 microtubular pattern. The basal diplosome was randomly associated with other cellular organelles including the Golgi complex, the endoplasmic reticulum, the microfilament network, the plasma membrane, vesicles and pits. Primary ciliogenesis is a new and unexpected finding in the epididymal epithelium. A monitoring role of luminal factors and extracellular liquids might be attributed to this organelle, likely acting as chemical receptor of the luminal environment, thus modulating the epithelial function by a cell-to-cell crosstalk involving the entire epithelium.

Morphological evaluation of the placenta and fetal membranes during canine pregnancy from early implantation to term.

To describe the histological changes of fetal adnexa throughout the physiological pregnancy, canine samples were obtained during natural delivery and caesarean section, as well as during ovariohysterectomy performed at any stage of undesired pregnancies (N=12). The first period of pregnancy (multiple samples collected at 10, 12, 14 days) was consistent with pre- and peri-implantation events, i.e. apposition and initial invasion steps into the endometrium. The second period (multiple samples collected at 18, 38, 40, 45 days) was related to the development of extra-embryonic structures, placenta establishment and labyrinth formation. At the end of this period the maximum morphological complexity of the endotheliochorial placenta was achieved, characterized by complete erosion of the endometrial epithelium and underlying interstitium with exposure of maternal capillaries to the chorial cells. The third period of gestation (multiple samples collected at 50, 53, 57, 60, 63 days) was characterized by enhancement either of placental and extra-embryonic tissues.

In situ characterization of glycans in the urothelium of donkey bladder: evidence of secretion of sialomucins.

The glycoprotein pattern was investigated by lectin histochemistry in the urothelium lining the urinary bladder of the donkey Equus asinus. Tissue sections were stained with a panel of twelve lectins, in combination with saponification and sialidase digestion (K-s). The urinary bladder urothelium has three distinct layers from the basal zone to the lumen consisting of basal, intermediate and superficial cells (umbrella cells). Cytoplasm of basal cells reacted with SNA, PNA, K-s-PNA, GSA I-B4 and Con A showing glycans ending with Neu5Acα2,6Gal/GalNAc, Neu5AcGalß1,3GalNAc, αGal and with terminal/internal αMan. The cytoplasm of umbrella cells displayed an increase of Neu5AcGalß1,3GalNAc and the appearance of Neu5AcGalß1,3GalNAc, Neu5acα2,3Galß1,4GlcNAc and Neu5AcGalNAc residues (MAL II, K-s-SBA and K-s-HPA staining). Scattered umbrella cells were characterized by glycans terminating with GalNAc binding DBA, SBA and HPA. The mucosa forms folds with a crypt-like appearance where the urothelium shows a different pattern of glycans. The bladder luminal surface stained with K-s-PNA, K-s-DBA, KOH-s-SBA, and K-s-HPA displaying a coating of sialoglycoproteins belonging to O-linked glycans (typical secretory moieties). These findings show that different glycosylation patterns exist along the donkey bladder urothelium, and different sub-populations of umbrella cells are present secreting the sialoglycans which constitute the protective gel layer lining the bladder.

Aquaporin water channels in the canine gubernaculum testis.

The jelly-like gubernaculum testis (GT) is a hydrated structure consisting of a concentric sheath of dense connective tissue around a loose mesenchymal core, with two cords of skeletal muscle cells asymmetrically placed alongside. Expansion of the GT occurs during the transabdominal phase of testicular descent, linked to cell proliferation together with modifications of the hydric content of the organ. The aim of this study was to detect immunohistochemically the presence of aquaporins (AQPs), integral membrane proteins permitting passive transcellular water movement, in the canine GTs. Samples (n=15) were obtained from pregnancies of 9 medium sized bitches and dissected from healthy fetuses. Five fetuses were aged 35-45 days of gestation, 10 fetuses from 46 days of gestation to delivery, thus offering us the opportunity to study the progressive maturation of the gubernacula. The presence of AQP3, 4, 7, 8 and -9 was assessed in the muscular components of the GT, some of them (AQP3, AQP4, AQP7) with increasing intensity through the second half of pregnancy up to term. AQP1 was localized in the capillary and venous endothelia in the younger fetuses, also in the artery adventitia and in the nerve perineurium in progressively older fetuses. These data demonstrate the potential importance and contribution of AQP-mediated water flux in hydration and volume modification of the growing GT in a canine model.

The anatomy of the dog soft palate. II. Histological evaluation of the caudal soft palate in brachycephalic breeds with grade I brachycephalic airway obstructive syndrome.

In brachycephalic dogs, the skull bone shortening is not paralleled by a decreased development of soft tissues. Relatively longer soft palate is one of the main factors contributing to pharyngeal narrowing during normal respiratory activity of these dog breeds, which are frequent carriers of the brachycephalic airway obstructive syndrome (BAOS), which affects most part of them during their postnatal life. No histological studies assessing the morphology and the normal tissue composition of the soft palate in brachycephalic dogs are available, neither has ever been determined whether the elongated soft palate is a primary or secondary event. Aim of this study was to describe the morphology of the caudal soft palate in brachycephalic dogs with Grade I BAOS to identify potential features possibly favoring the pathogenesis of BAOS. Specimens from brachycephalic dogs (N = 11) that underwent preventive surgery were collected from surgery, processed for histology, and examined at six transversal levels. The brachycephalic soft palates showed peculiar features such as thickened superficial epithelium, extensive oedema of the connective tissue, and mucous gland hyperplasia. Several muscular alterations were evidenced in addition. The results of this investigation add to the general knowledge of the anatomy of soft palate in the canine species and establish baseline information on the morphological basis of the soft palate thickening in brachycephalic dogs.

The anatomy of the dog soft palate. I. Histological evaluation of the caudal soft palate in mesaticephalic breeds.

The gross anatomy and overall structure of the soft palate has been described in the average dog's head, however, no descriptive microanatomical studies of the dog soft palate are available, despite their possible utility in view of the manifold and important repercussions of this organ physiology. This is the first of two companion papers, dealing with the caudal part of the soft palate in the canine species, in mesaticephalic and brachycephalic dogs. Specimens from mesaticephalic healthy dogs (N = 8) were collected after euthanasia, processed for histology and sectioned at six transversal levels. Morphological stainings were used for a microscopic evaluation of the tissue layers composing the distal part of the soft palate in adult mesaticephalic dogs, and histochemical reactions were applied to assess mucin types within glandular tissue and to investigate the connective tissues. The organ was characteristically organized into a major deep musculo-connective axis mixed with salivary glands and covered by the mucosal lining on either the nasopharyngeal or the oral sides. The results of this investigation add to the general knowledge of the anatomy of soft palate in the canine species and establish baseline information for the parallel study on the long and thickened soft palate, which is typical of adult brachycephalic dogs.

Immunodetection of aquaporin 5 in sheep salivary glands related to pasture vegetative cycle.

Mammalian aquaporins (AQPs) are a family of at least 13 integral membrane proteins expressed in various epithelia, where they function as channels to permeate water and small solutes. AQP5 is widely expressed in the exocrine gland where it is likely involved in providing an appropriate amount of fluid to be secreted with granular contents. As regards AQP5 expression in the salivary glands, literature is lacking concerning domestic animal species. This study was chiefly aimed at immunohistochemically investigating the presence and localization of AQP5 in sheep mandibular and parotid glands. In addition, AQP5 immunoreactivity was comparatively evaluated in animals fed with forage containing different amounts of water related to the pasture vegetative cycle, in order to shed light on the possible response of the gland to environmental modifications. Moderate AQP5-immunoreactivity was shown at the level of the lateral surface of mandibular serous demilune cells, not affected by the pasture vegetative cycle or water content. On the contrary, the parotid gland arcinar cells showed AQP5-immunoreactivity at the level of apical and lateral plasma membrane, which was slight to very strong, according to the pasture vegetative development and interannual climatic variations. AQP5 expression is likely due to its involvement in providing appropriate saliva fluidity. Indeed, the lowest AQP5 immunoreactivity was noticed when food water content increased.

Identification of C-kit-positive interstitial cells in the dog lower urinary tract and relationship with smooth muscle and nerves. Hypotheses for a likely pacemaker role.

The aim of this work was to give an evidence of the likely presence of interstitial cells in the canine lower urinary tract and to study their possible interactions with the musculature and the intramural innervation. Cryosections of normal canine bladder and urethra were immunofluorescently labelled with c-kit, a transmembrane, tyrosine kinase growth factor receptor, known to be expressed on the interstitial cells of Cajal (ICCs) of the gut. The relationship with antiactin positive smooth muscle cells and PGP9.5-positive intramural innervation was also investigated by confocal microscopy. Anti-c-kit labelling demonstrated a network of elongated and branched c-kit positive cells, which were located in interstitial spaces, oriented in parallel to the smooth muscle bundles that form the bladder muscular layer, irrespective of dog sex. Cells with a similar localization were also PAS- and NADPH-diaphorase-positive. A contact between c-kit immunofluorescent cells and intramural innervation was demonstrated, too. The roles of interstitial cells might include regulation of smooth muscle activity of the bladder detrusor, integrating neuronal signals during urine storage and voiding.

An immunohistochemical study on the neuroendocrine system in the alimentary canal of the brown trout, Salmo trutta, L., 1758.

Several neurohormonal peptides of the gastrointestinal system of fish have been revealed by immunohistochemical methods. Among salmonids, the rainbow trout, Oncorhynchus mykiss (Walbaum) is the most studied species, whereas the informations about other species of the taxonomic group are lacking. The regional distribution and relative densities of cells belonging to the neuroendocrine system have been in this paper demonstrated in the gut of the brown trout, Salmo trutta Linnaeus. In the gastric mucosa, endocrine cells were detected, which were immunoreactive to bombesin-, gastrin-, and secretin-antisera. Endocrine cells containing gastrin-, bombesin-, cholecystokinin-8-, glucagon-, and leptin-like immunoreactivities were present in the pyloric caeca and intestine. The pancreatic endocrine islets contained glucagon-, and, possibly, secretin-like-immunoreactive endocrine cells, as well as a contingent of galanin-like-immunoreactive nerve fibres. The exocrine pancreatic parenchyma showed bombesin-like-immunoreactive nerve fibres. Within the tested regulatory peptides, bombesin and leptin were observed in both endocrine cells and nerve cell bodies and fibres. Leptin was in addition detected in epithelial cells of the gastric glands. In the brown trout we have never observed any immunoreactivity to the VIP antiserum (either in the stomach or in the intestine). Some special structural patterns (in particular those ones related to galanin- and leptin-immunohistochemical data) have thus been detected for the first time in the brown trout, and provide further data for a better knowledge of gut morpho-functional aspects in this economically important fish.