Anna Maria Rambaldi

In collaboration with the American College of Veterinary Pathologists

Herpesviruses are causative agents of meningitis and encephalitis in cetaceans, which are among the main leading known natural causes of death in these species. Brain samples from 103 stranded cetaceans were retrospectively screened for the presence of herpesvirus DNA in the brain. Molecular detection of Cetacean Morbillivirus was performed in HV positive brain cases. Histopathologic evaluation of brain samples included the presence or absence of the following findings (n = 7): meningitis, perivascular cuffings, microgliosis, intranuclear inclusion bodies, malacia, neuronal necrosis and neurophagic nodules, and haemorrhages. Histological evidence of the involvement of other etiological agents led to complementary analysis. We detected the presence of alpha and gamma-HVs in 12 out of 103 (11.6%) brain samples from stranded cetaceans of five different species: one bottlenose dolphin, six striped dolphins, three Atlantic spotted dolphins, one Cuvier’s beaked whale, and one common dolphin. Pathogenic factors such as viral strain, age, sex, and the presence of co-infections were analysed and correlated with the brain histopathological findings in each case. Herpesvirus was more prevalent in males, juveniles, and calves and a 41.6% incidence of co-infections in the brain was detected in our study: three with Dolphin Morbillivirus, one with Staphilococcus aureus septicaemia and one with Brucella spp.

Compared with other mammals, the digestive system of cetaceans presents some remarkable anatomical and physiological differences. However, the neurochemical features of the enteric nervous system (ENS) in these animals have only been described in part. The present study gives a description of the nitrergic and selected peptidergic systems in the myenteric plexus (MP) and submucosal plexus (SMP) of the intestine of the bottlenose dolphin (Tursiops truncatus). The distribution and morphology of neurons immunoreactive (IR) for the neuronal nitric oxide synthase (nNOS) and Substance P (SP) were immunohistochemically studied in formalin-fixed specimens from the healthy intestine of three animals, and the data were compared with those described in the literature on other mammals (human and non-human). In bottlenose dolphins, the percentages of nitrergic neurons (expressed as median and interquartile range—IQR) were 28% (IQR = 19–29) in the MP and 1% (IQR = 0–2) in the SMP, while the percentages of SP-IR neurons were 31% (IQR = 22–37) in the MP and 41% (IQR = 24–63) in the SMP. Although morphological features of nNOS- and SP-IR neurons were similar to those reported in other mammals, we found some noticeable differences in the percentages of enteric neurons. In fact, we detected a lower proportion of nNOS-IR neurons in the SMP and a higher proportion of SP-IR neurons in the MP compared to other mammals. To the best of the authors’ knowledge, this study represents the first description and quantification of nNOS-IR neurons and the first quantification of SP-IR neurons in the intestine of a cetacean species. As nNOS and SP are important mediators of intestinal functions and the nitrergic population is an important target for many neuroenteropathies, data obtained from a healthy intestine provide a necessary basis to further investigate and understand possible functional differences and motor intestinal dysfunctions/alterations in these special mammals.

Testicular neoplasms have been extensively described and characterized in domestic animals, but reports in wildlife species, including marine mammals, are scarce. This case report describes a testicular seminoma in an adult striped dolphin Stenella coeruleoalba stranded along the coasts of the Canary Islands. Post-mortem computerized tomography (CT) showed a prominent enlargement of the cranial pole of the right testicle, displacing the intestinal loops. Necropsy gross findings confirmed the presence of a testicular mass, bulging at the cut surface, with multiple well-delimitated whitish nodular lesions. Histologically, intratubular and diffuse neoplastic germinative cell proliferation was described. Complementary immunohistochemical assessments for vimentin and CD117 antibodies were negative. To the authors’ knowledge, this is the first seminoma described in a S. coeruleoalba. We suggest that post-mortem (PM) pre-necropsy CT in dolphins is a useful tool for anatomic-guided pathology in such cases.

The amgdaloid complex consists of different nuclei, each with unique cytoarchitectonic, chemoarchitectonic and connectional characteristics. Most of the inputs coming from cortical and subcortical areas enter the amygdala via the lateral nucleus, which makes it the main receiving structure of the complex. The activity of its neurons is coordinated and modulated by different inhibitory, GABAergic‐interneurons, which can be classified for their expression of various calcium‐binding proteins, as well as by morphological characteristics. This research based on the analysis of the amygdala of three bottlenose dolphins, provides the first description of the topography, cytoarchitecture and distribution of calretinin immunoreactivity of the lateral nucleus. Our observations on the bottlenose dolphin confirmed the general topography of the mammalian amygdala and of the lateral nucleus. Notably, we identified six subdivision of the nucleus, more than those reported until now in the rat, monkey and human lateral nucleus. This could reveal an outstanding capability of integration and elaboration of external stimuli. In addition, we observed a strong presence of CR‐immunoreactive (‐ir) neurons and fibres. CR‐ir neurons were mainly non‐pyramidal inhibitory neurons; in particular, 80% of IR‐cells were represented by large and small polygonal neurons. In the lateral nucleus of the human amygdala, CR‐ir neurons form inhibitory synapses on calbindin‐D28k‐IR inhibitory interneurons. Since calbindin‐D28k‐ir interneurons make inhibitory synapses on the pyramidal cells, the final goal of the CR‐ir interneurons could be the synchronization of cells activity, thus playing an important role in the control of information flow in the lateral amygdalar nucleus. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:2008–2016, 2017.

Background: Serotonin plays a pivotal role in regulating gut motility, visceral sensitivity, and fluid secretion via specific receptors. Among these receptors, 5‐HT₄exerts a prominent control on gut motor function. Although the prokinetic effect exerted by 5‐HT₄agonists is well known, the cellular sites of 5‐HT₄expression remain poorly understood in large mammals, e.g., horses. In this study, we evaluated the distribution of 5‐HT₄in the horse intestine and in foals with enteric aganglionosis, reminiscent of human Hirschsprung's disease.Methods: The intestine and spinal ganglia were obtained from three healthy horses and two foals with hereditary ileocolonic aganglionosis. Tissues were processed for immunohistochemistry using a specific antibody to 5‐HT₄and a variety of neuronal markers. Myenteric and submucosal plexus 5‐HT₄‐immunoreactive (IR) neurons were quantified as relative percentage (mean±SD) to the total number of neurons counted. Furthermore, the density of 5‐HT₄‐IRnerve fibers was evaluated in the mucosa andtunica muscularis.Key Results: The 5‐HT₄immunoreactivity was localized to large percentages of myenteric neurons ranging from 28±9% (descending colon) to 63±19% (ileum), and submucosal neurons ranging from 54±6% (ileum) to 68±14% (duodenum). The 5‐HT₄‐immunoreactivity was co‐expressed by some substance P‐IR(SP‐IR) spinal ganglion neurons and extrinsic sensory fibers of aganglionic foals.Conclusions & Inferences: The presence of 5‐HT₄in many enteric and extrinsic sensory neurons and nerve fibers provides solid morphological evidence of the cellular sites of 5‐HT₄expression in horses. The evidence ofSP‐IRsensory neurons positive for 5‐HT₄suggests its role in visceral sensitivity.

Given the limited information regarding the anatomy of the thoracic limb in European avian species, we decided to investigate the related muscles in the grey heron (Ardea cinerea), in the eurasian buzzard (Buteo buteo), and in the common kestrel (Falco tinnunculus). Therefore we performed a stratigraphic dissection of the wing in 3 subjects. The pars major and minor of the musculus deltoideus, despite being roughly in line with those reported by other authors in other species, displayed unique features. Concerning the pars propatagialis of the musculus deltoideus, from what was observed in the grey heron, we believe this structure can contribute to maintain the propatagial tension. In this way vibrations of this structure, which could cause diminished lift, are avoided. Moreover the peculiarity evidenced in the distal insertion of the common kestrel could influence the control of the pronation-supination of the wing during hovering. With respect to the musculus flexor carpi ulnaris, we believe the presence of a sesamoid-like structure at the base tendon, found in the grey heron and in the eurasian buzzard, may help complete the articular surfaces of the elbow. This study shows interesting data on species not previously examined and provides a possible functional correlation between the peculiarity observed and the kind of flight of each species.