Spatio-temporal patterns in stable isotope composition of a benthic intertidal food web reveal limited influence from salt marsh vegetation and green tide.

Assessing fluxes of matter and energy in food webs within and across benthic habitats is important to understand the ecological functioning in bays and estuaries, where the productivity is favoured by a wide diversity of primary producers. The temporal variability (March vs September 2019) in the carbon and nitrogen stable isotope composition of primary food sources and benthic invertebrates consumers was investigated in a large intertidal area (Western English-Channel, France). The study area is influenced by megatidal conditions and characterised by salt marshes in the sheltered part, and seasonal Ulva spp. blooms. The spatio-temporal variability in the structure of the benthic food web was analysed at the scales of both the whole bay and the different assemblages, which constitute the mosaic of habitats. Inferences on potential sources fuelling the food web were supported by spatio-temporal patterns based on covariations and stable isotope trajectory analysis. Results highlighted that phytoplankton, microphytobenthos and SOM were, most likely, the main food sources. The trophic connectivity between salt marsh and benthic habitats within the bay was limited to some macrofauna species inhabiting muddy creeks within the salt marsh. Unexpectedly, the influence of Ulva spp. blooms appeared also limited. Spatial patterns illustrates the constancy of the spatial variability in the benthic pelagic coupling, with a higher influence of microphytobenthos in the upper shore compared to low shore assemblages. This first attempt to characterize intertidal benthic food web constitutes a relevant baseline for the conservation of the bay of Saint-Brieuc where a national Nature Reserve has been created in 1998 for the conservation of overwintering birds. The spatial and temporal patterns of the benthic food web observed in this study (1) confirm the importance to consider food web variability at spatial and temporal scales from sampling designs to data analysis, and (2) demonstrate the ability of the stable isotope trajectory analysis framework to highlight food web dynamics.

Stomach content and stable isotope analyses provide complementary insights into the trophic ecology of coastal temperate bentho-demersal assemblages under environmental and anthropogenic pressures.

Assessing organic matter fluxes and species interactions in food webs is of main interest to understand the ecological functioning in bays and estuaries characterised by a wide diversity of primary producers and consumers. Demersal fish and cephalopod assemblages were studied across a network of 24 shallow subtidal stations in the bay of Saint-Brieuc for their diversity, stable isotope compositions and stomach contents. The community was composed of 21 taxa, eight species accounting for 94.4% of the total abundance. Three different assemblages were identified along bathymetric gradient and spatial patterns in fish dredging. Marine POM and SOM were the most likely bases of food webs regarding δ13C range displayed by fish and cephalopod without differences among assemblages. Amphipoda was the main prey item in stomachs leading to significant diet overlaps among fish species, with some variations in additional items. Sepia officinalis was characterised by a singular diet and very low dietary overlap with other species. Contrasted stable isotope values and niche overlaps among species were evidenced in the δ13C/δ15N space. Callionymus lyra and Buglossidium luteum, characterised by the widest isotopic niches, encompassed those of other species, except the singular 13C-depleted Spondyliosoma cantharus. Coupling taxonomic assemblages, stomach contents and stable isotope analyses help disentangling the resources uses and evidencing trophic pathways. Contrasts in fish and cephalopod demersal assemblages occurring at different depths not necessarily imply differences in the trophic resources uses in such complex shallow coastal ecosystems under anthropogenic influences.

Effect of sow vaccination against Mycoplasma hyopneumoniae on sow and piglet colonization and seroconversion, and pig lung lesions at slaughter.

The objectives of the present study were to compare Mycoplasma hyopneumoniae (Mh) colonization and serologic status on Mh vaccinated and non-vaccinated sows and to assess the effect of sow vaccination on colonization and serologic status of their piglets at weaning as well as presence of enzootic pneumonia (EP) lung lesions at slaughter. Fifty sows (25 vaccinated and 25 unvaccinated) as well as five of their piglets were included in the study. Blood samples and nasal swabs from sows at 7 weeks pre-farrowing and 1 week post-farrowing and from piglets at 3-4 weeks of age were taken. Nasal swabs and sera were tested by a nested polymerase chain reaction (nPCR) to detect Mh DNA and by an enzyme-linked immunosorbent assay (ELISA) test to detect antibodies to the pathogen, respectively. Finally, at 23 weeks of age, pigs were sent to the slaughter where the extension of EP-compatible gross lesions was assessed. Vaccination with two doses of Mh vaccine resulted in a significantly higher (p<0.05) percentage of seropositive sows than in the non-vaccinated group at 1 week post-farrowing. On the contrary, no statistical significant differences were found in the number of nasal nPCR positive sows among different treatments (p>0.05). At 3-4 weeks of age, a significantly higher percentage (p<0.001) of seropositive piglets came from vaccinated than from non-vaccinated sows. Although the number of Mh infected piglets coming from non-vaccinated sows was higher than the one from vaccinated sows, the difference was not statistically significant (p>0.05). Overall, piglets from vaccinated sows had a significant lower (p<0.05) mean of EP-compatible lung lesions (1.83+/-2.8) than piglets from non-vaccinated sows (3.02+/-3.6). Under the conditions described in this study, sow vaccination did not affect sow or piglet colonization but increased the percentage of seropositive sows and piglets at weaning and reduced significantly the mean EP-compatible lung lesion scoring at slaughter.

Simultaneous detection and genotyping of porcine reproductive and respiratory syndrome virus (PRRSV) by real-time RT-PCR and amplicon melting curve analysis using SYBR Green.

The feasibility of using a SYBR Green-based real-time RT-PCR assay (SYBR Green ReTi RT-PCR) followed by melting curve analysis (MCA) for detecting and genotyping porcine reproductive and respiratory syndrome virus (PRRSV) was assessed. The SYBR Green ReTi RT-PCR and a previously reported two-step, non-nested RT-PCR assays were simultaneously tested on selected European (EU) and North American (US) PRRSV strains and isolates collected from diverse clinical, temporal, and geographical origins. The validation experiments showed that the optimised SYBR Green ReTi RT-PCR can sensitively and specifically detect PRRSV, consistently detecting as little as 0.03TCID(50)/sample of each virus genotype, with no type-bias and no amplification signal for other swine pathogens. After MCA, two well-differentiated melting temperature (T(m)) profiles for each virus genotype were obtained, as sequencing confirmed it. High repeatability was obtained for the T(m) values, with intra-run coefficients of variation (CoVs) of 0.25 and 0.32 and inter-run CoVs of 0.42 and 0.52 for EU and US genotypes, respectively. The sensitivity of the SYBR Green ReTi RT-PCR (100%) was higher than that of the RT-PCR (95.7%) when testing field isolates. This greater sensitivity of the SYBR Green ReTi RT-PCR was further confirmed by the detection of a higher proportion of PRRSV-positive diagnostic specimens (29.7%) than by the RT-PCR (28.5%). The SYBR Green ReTi RT-PCR test detected infection as early as 2 dpi in the sera of experimentally infected pigs regardless of virus genotype, and discriminated negative (non-inoculated), EU- and US-infected pigs. In conclusion, the reported SYBR Green ReTi RT-PCR assay coupled with MCA can detect and type PRRSV and may be useful as an alternative diagnostic assay in diverse PRRSV epidemiological circumstances.

Exploratory field study on Mycoplasma hyopneumoniae infection in suckling pigs.

The present study focused on Mycoplasma hyopneumoniae (M. hyopneumoniae) detection by nPCR in nasal swabs of 507 suckling pigs. These animals came from 69 sows (from 1 to 8 parity number) of a farrow-to-finish herd with Enzootic Pneumonia (EP) problems at finishing stages. At 1 and 3 weeks of age (still in the farrowing units), nasal swabs and blood samples were taken from all piglets. Moreover, from these 507 animals, 37 randomly selected pigs were necropsied at 3 weeks of age. From those necropsied pigs, M. hyopneumoniae presence was tested in bronchial and tonsillar swabs. At 1 week post-farrowing, blood samples from sows were collected and used to detect M. hyopneumoniae antibodies. From the 69 analysed sows, 19 (27.5%) were seropositive. Global percentage of pigs with M. hyopneumoniae detection in nasal swabs at 1 and 3 weeks of age was 1.5% (8 out of 507) and 3.8% (19 out of 507), respectively. From these nPCR positive pigs, 89% (24 out of 27) were seronegative and 11% were seropositive. From necropsied animals, the pathogen DNA was detected in two pigs at bronchus level and in another pig at tonsil. In this study, sow parity was not statistically related with sow seropositivity and piglet colonization. These results confirm that M. hyopneumoniae infection may be detected not only in nasal cavities of naturally infected suckling piglets but also at their low respiratory tract airways. Our results suggest that M. hyopneumoniae detection in lower and upper respiratory tract could be an indicator that respiratory problems associated to EP may start relatively early in the production system. In consequence, sow-to-piglet and/or piglet-to piglet transmission in farrowing barns should not be underestimated.

Multiple effects of a Gracilaria vermiculophylla invasion on estuarine mudflat functioning and diversity.

The invasive Japanese seaweed Gracilaria vermiculophylla has become established over the past several years in numerous European estuaries, from Portugal to Norway. In the Faou estuary (48.295°N-4.179°W, Brittany, France), it forms a dense population at the mud's surface. The effects of G. vermiculophylla on metabolism, diversity, and the food web were studied. Community gross primary production (GPP) and respiration (CR) during emersion, chlorophyll-a content, macrofaunal and meiofaunal diversity and abundance, and stable isotopes (δ13C and δ15N) of representative macrofaunal species and main food sources were measured at low tide in winter, spring, summer 2014, and winter 2015. Results show significant seasonal variation in GPP and CR. Moreover, GPP was significantly higher in areas where G. vermiculophylla was present than in the control area (bare mud). However, this high GPP appeared to be linked to the increase in biomass in primary producers, with their efficiency (primary productivity, i.e. assimilation number) remaining relatively stable compared with the control area. Significant variation in abundance of meiofauna and macrofauna was also detected and new epifaunal species were collected, mainly in Gracilaria-colonized areas. Isotopic food-web Bayesian mixing models strongly suggested that G. vermiculophylla plays a major role in the diet of some dominant species. Mechanisms interacting with the functioning and diversity of the mudflat are discussed. Finally, the invasive seaweed G. vermiculophylla affected the mudflat ecosystem in three ways: as a new primary producer (increase in metabolism), as a habitat-forming species (changes in diversity and abundance of macrofauna and meiofauna), and as a new abundant food source, likely through the detrital pathway.

Hernia enlargement and pancreatitis in a patient with short bowel syndrome treated with teduglutide / Crecimiento de hernias y pancreatitis en una paciente con síndrome de intestino corto tratada con teduglutida

Introduction: teduglutide (TED) is indicated for the treatment of patients with short-bowel syndrome (SBS) who are dependent on parenteral support. Case report: we report the case of a 60-year-old woman with SBS treated with TED. She had previously undergone multiple surgical resections due to Crohn's disease. Her remnant bowel included only the duodenum and 50-60 centimeters of jejunum. The patient was dependent on intravenous fluids (2,320 mL/48 h) and had a high stoma output (3,000 mL/day). After four months of TED the jejunostomy output had decreased to 2,200 mL/day with a thicker consistency, and intravenous fluid therapy was reduced to 2,010 mL/48 h. TED was withdrawn due to acute pancreatitis and enlargement of two supraumbilical hernias with high strangulation risk. Discussion: pancreatitis has been reported in clinical studies, and determination of amylase and lipase is recommended in all patients receiving TED. In contrast, there are no recommendations for the surveillance of hernia enlargement in patients on TED therapy, but we suggest the need for surveillance based on this case report (AU)

Introducción: la teduglutida (TED) está indicada para el tratamiento de pacientes con síndrome de intestino corto (SBS) que precisen soporte parenteral. Caso clínico: mujer de 60 años con SBS tratada con TED. Previamente se había sometido a múltiples resecciones quirúrgicas por su enfermedad de Crohn. Su intestino remanente incluía el duodeno y 50-60 centímetros de yeyuno. La paciente era dependiente de líquidos por vía intravenosa (2320 ml/48 h) y tenía una ostomía de alto débito (3000 ml/día). Después de cuatro meses de TED, el débito de la yeyunostomía disminuyó a 2200 ml/día, con una consistencia más espesa, y la fluidoterapia intravenosa se redujo a 2010 ml/48 h. Se retiró la TED por pancreatitis aguda y agrandamiento de dos hernias supraumbilicales con alto riesgo de estrangulamiento. Discusión: se han descrito casos de pancreatitis en estudios previos, por lo que se recomienda la determinación de la amilasa y la lipasa en los pacientes tratados con TED. Sin embargo, no hay recomendaciones específicas sobre la vigilancia del agrandamiento de hernias, pero sugerimos su idoneidad basada en este caso clínico (AU)

Estatus epiléptico: seguimiento e individualización farmacoterapéutica / Status epilepticus: follow-up and pharmacotherapy individualization

El estatus epiléptico superrefractario es un cuadro muy grave que pone en riesgo la vida de los pacientes. En este sentido, la monitorización rigurosa de los antiepilépticos es clave para un desenlace favorable. La excepcionalidad del caso presentado radica en la superrefractariedad del cuadro, que dificultó su manejo terapéutico y requirió un elevado grado de implicación del farmacéutico hospitalario en el seno de un equipo multidisciplinar. (AU)

Super-refractory epileptic status is a really serious and life-threatening condition. In this sense, rigorous monitoring of antiepileptic drugs is key to a favourable outcome. The exceptionality of the case presented lies in the super-refractoriness of the clinical profile, which made its therapeutic management difficult and required a high degree of involvement of the pharmacist’s hospital within a multidisciplinary team. (AU)

Identification of viral pathogens in aborted fetuses and stillborn piglets from cases of swine reproductive failure in Spain.

The objective of the present study was to determine the presence of recognised abortifacient viruses such as porcine reproductive and respiratory virus (PRRSV), Aujeszky's disease virus (ADV), porcine parvovirus (PPV) and porcine circovirus type 2 (PCV2), in tissues from aborted fetuses and stillborn neonates in cases of late reproductive failure in swine. A total of 293 specimens (fetuses aborted in the last third of gestation and stillborn piglets) from 100 different cases of late-term abortions and premature farrowing from 15 different Spanish provinces were studied. PRRSV was detected in 9/100 cases by RT-PCR. Only 1/100 cases analysed (corresponding to a late-term aborted fetus with a negative PRRSV RT-PCR result) was positive for PCV2 by PCR. Neither ADV (monitored by viral isolation plus antigen detection) nor PPV (monitored by ELISA antigen capture test) infection was identified. The results suggest that PRRSV is one of the most important infectious agents, if not the most relevant one, associated with fetal infection leading to abortion or premature farrowing in Spain. Moreover, other viral pathogens such as ADV, PPV and PCV2 seem to have a minor impact on reproductive disease.

Spontaneous congenital hydrocephalus in the mutant mouse hyh. Changes in the ventricular system and the subcommissural organ.

The subcommissural organ is an ependymal gland located at the entrance of the cerebral aqueduct. It secretes glycoproteins into the cerebrospinal fluid, where they aggregate to form Reissner's fiber. This fiber grows along the aqueduct, fourth ventricle, and central canal. There is evidence that the subcommissural organ is involved in the pathogenesis of congenital hydrocephalus. This organ was investigated in the mutant mouse hyh developing a congenital hydrocephalus. The central nervous system of normal and hydrocephalic hyh mice, 1 to 40 days old, was investigated using antibodies recognizing the subcommissural organ secretory glycoproteins, and by transmission and scanning electron microscopy. At birth, the affected mice displayed open communications between all ventricles, absence of a central canal in the spinal cord, ependymal denudation of the ventricles, stenosis of the rostral end of the aqueduct, and hydrocephalus of the lateral and third ventricles and of the caudal end of the aqueduct. Around the 5th postnatal day, the communication between the caudal aqueduct and fourth ventricle sealed, and hydrocephalus became severe. It is postulated that the hyh mice carry a genetic defect affecting the ependymal cell lineage. The subcommissural organ showed signs of increased secretory activity; it released to the stenosed aqueduct a material that aggregated, but it did not form a Reissner's fiber. A large area of the third ventricular wall differentiated into a secretory ependyma synthesizing a material similar to that secreted by the subcommissural organ. It is concluded that the subcommissural organ changes during hydrocephalus; whether these changes precede hydrocephalus needs to be investigated.

Distribution of neuropeptide Y-like immunoreactivity in the brain of Salmo salar and Gambusia affinis.

Through the immunohistochemical PAP technique, the distribution of immune positive neurons and fibres for an antibody anti-NPY in the encephalon of salmon fixed in Bouin have been located and studied. NPY-positive neurons are found forming three important nuclei: in the ventrolateral telencephalon; in the tegmentum mesencephali; and in the locus coeruleus. Neurons in the optic tectum, in the thalamic region and a few in the preoptic recess have also been located. The fibres were found throughout the brain, with the exception of the cerebellum, presenting a greater density in three regions: in the dorsal telencephalon; in the mesencephalon; and in the visceral lobes in the rhombencephalon. With the aim of proving if this distribution is found in other groups of teleosts, we processed, with the same technique, the advanced teleost Gambusia affinis, in order to compare it with the primitive teleost Salmo salar. The results show that in both fish this neuropeptide has the same pattern of distribution. The results also suggest that in fish this neuropeptide can be involved in several functions of the central nervous system, as has been demonstrated for mammals. The innervation of the visceral lobes and also the presence of NPY-fibres in the posterior hypothalamus are anatomical supports of the studies which suggest that NPY is related to the control of the food intake.

The distribution of corticotropin-releasing factor immunoreactive neurons and nerve fibres in the brain of Gambusia affinis and Salmo trutta.

The study was carried out on the distribution of neurons and fibres which contain the Corticotropin releasing factor-like (CRF) immunoreactivity in the encephalon of two species of teleosts, Gambusia affinis and Salmo trutta. The peroxidase-antiperoxidase (PAP) immunocytochemical technique was employed. The present study has shown differences between both species. In Gambusia affinis, positive neurons were observed in the area ventralis telencephali pars lateralis (VLT), in the nucleus praeopticus (NPO) and in the nucleus lateralis tuberis (NLT). The immunoreactive fibres were in the area ventralis telencephali, in the preoptic hypophyseal tract and in the hypophysis. In Salmo trutta the immunoreactive cells were seen in the pars magnocellularis and pars parvocellularis of the NPO and in cerebrospinal fluid (CSF) contacting neurons of the NLT. The pattern of distribution of immunoreactive fibres in Salmo trutta was different from that in Gambusia affinis. In addition to the distribution of perikarya in Gambusia affinis (in the VLT and in the preoptic hypophyseal tract), fibres were also observed in the tubero-hypophyseal tract and in the posterior hypothalamus. The hypophysis of Salmo trutta also presents an extensive labelling. The interspecific differences shown in the present study should be due to the different degree of evolution in the two species studied and to other causes, such as environmental ones.

Hindbrain floor plate of the rat: ultrastructural changes occurring during development.

Most of the molecular and experimental studies on the floor plate (FP) have been performed on the FP region extending along the spinal cord. However, little is known about the hindbrain FP. The FP undergoes regional and temporal changes throughout development, but information with respect to the ultrastructural correlate of such changes is missing. The present investigation was focused on the ultrastructural developmental changes occurring in the FP of the rat hindbrain. The FP cells of the hindbrain secrete a material reacting with antibodies against the secretory glycoproteins of the subcommissural organ (AFRU). This antibody was used to perform an ultrastructural immunocytochemical analysis of the rat FP. From E-12 on, there is a progressive increase in the development of the rough endoplasmic reticulum (RER), so that by E-18, it has reached a high degree of hypertrophy. A unique feature of the hindbrain FP cells is the presence of tubular formations and 140-nm vesicles that appear to originate from RER cisternae. The labelling of these two structures with AFRU and Concanavalin A strongly suggests that they are pre-Golgi compartments containing secretory material. Since these structures are present in the basal process and in the apical cell pole of the FP cells, the possibility that they release their content at these sites, is discussed. It is proposed that a secretory mechanism bypassing the Golgi apparatus (constitutive secretion?) operates in the FP cells. The presence of apoptotic cells within the FP of E-20 embryos and newborns suggests that death, and not re-differentiation, is the fate of the FP cells.

Long-term complications of extraperiosteal plombage.

BACKGROUND: As soon as complications due to migration of extraperiosteal plombage material had been documented, early removal became the rule. Some patients who have escaped this rule may still present with long-term complications. METHODS: Since 1980, 14 patients aged 54 +/- 10 years were admitted 28 +/- 11 years after collapse therapy. Eight presented with signs of infection, 4 with hemoptysis, and 2 with periscapular pain. Vascular erosion, suspected in 3 patients, was demonstrated with angiograms in 1. RESULTS: Ablation of the material was combined with excision of the devitalized ribs in 13 patients. Femorofemoral bypass was used in 2 patients for repair of an aortic erosion. Single ablation of subcutaneously migrated material was performed in a poor-risk patient. Operative bleeding was moderate except in 2 patients; 1 of them died intraoperatively during repair of an aortic erosion. A second patient died postoperatively with a massive pulmonary embolus on day 11. Infection was diagnosed in 8 patients (Mycobacterium tuberculosis, 4; and pyogens, 4). Operative outcome was satisfactory in all 12 operative survivors. A single patient presented with an infected apical space at 1 year and underwent complementary resection of the first rib. CONCLUSIONS: We recommend routine ablation of any residual plombage material whenever operative risk is acceptable because of the high incidence of spontaneous complications.

The floor plate of the hindbrain is a highly specialized gland. Immunocytochemical and ultrastructural characteristics.

Although the participation of the floor plate (FP) in the differentiation of neurons in the ventral spinal cord is well established, the function of the FP at the level of the hindbrain is not known. The present investigation was focused on the FP of the rat hindbrain. We used an antibody specifically labeling the rat FP (FP4) and an antiserum raised against the secretory glycoproteins of the subcommissural organ that also reacts with an intracellular material in the FP. Immunocytochemical and ultrastructural evidence was obtained indicating that the rostralmost end of the FP, at the metencephalon, is a highly specialized gland which differentiates early and undergoes regression before birth. The material(s) secreted by these FP cells appear to be transported downward into their basal processes, and upward into ventricular protrusions. It is proposed that the former would participate in the differentiation of the serotonergic neurons, and the latter could be released into the ventricle and reach distant targets. Furthermore, evidence is presented supporting the occurrence of regional and temporal specializations of the FP.

Prevalence of Haemophilus parasuis serovars isolated in Spain from 1993 to 1997.

From 1993 to 1997, 327 strains of Haemophilus parasuis were isolated from spanish swine in our Diagnostic Laboratory and 174 strains (53.2%) were serotyped. Four serotypes, sv. 5 (18.4%), sv 4 (16%), sv. 2 (9.2%) and sv. 13 (8%) were the most frequently isolated and 29.3% of the studied strains were classified as non typable. The results obtained indicate that the distribution of the serotypes in Spain is very similar to that found by other researchers in Germany, Australia, Canada and alike to that found in the United States.

Isolation and characterisation of circoviruses from pigs with wasting syndromes in Spain, Denmark and Northern Ireland.

A porcine circovirus (PCV) was isolated from tissues of pigs with wasting syndromes from Spain, Denmark and N. Ireland. The antigenic profiles of these viruses were determined by indirect immunofluorescence assays using polyclonal antisera and monoclonal antibodies (mAbs) prepared against previously isolated PCVs. A rapid and convenient PCR-based test was developed and used for the genotyping of these PCV isolates. These PCV isolates were found to be antigenically and genomically similar to previously reported isolates of PCV from pigs with wasting disease (PCV2), but distinct from the isolate of PCV from continuous PK/15 cell cultures (PCV1).

Cell types of the third ventricle wall of the rabbit (Oryctolagus cuniculus).

A comparative study using optical and electron transmission and scanning microscopes was carried out to determine the cells that comprise the wall of the third ventricle of the rabbit (Oryctolagus cuniculus). Three cell types have been distinguished: type I cells are the most numerous and may present a flat, cubical or cylindrical aspect, with cilia and microvilli at their apical end. Type II cells have an irregular elongated morphology, lack cilia on their luminal end and show functional characteristics of secretory cells. Type III cells are also elongated, and bear irregular protrusions at the apical end. A long process at the basal end of these cells goes deep into the neuropil and becomes related with neurons or blood vessels; these correspond to tanycytes.

Ultrastructural study of the cellular components of the organum vasculosum lamina terminalis of the rabbit (Oryctolagus cuniculus).

We studied the organum vasculosum of the lamina terminalis (OVLT), under the electron microscope (transmission and scanning) to determine its ultrastructural features. Two cell types are differentiated. Type I cells are typical ependymal cells bearing few cilia. Type II cells present a tanycytic morphology. The latter present a long basal process which travels from the perikarya and intermingles with other neuronal components, finally reaching the perivascular spaces where it comes into close contact with fenestrated capillaries.

Supraependymal cell clusters and invaginations in the epithalamic third ventricle of the rabbit (Oryctolagus cuniculus).

Supraependymal cell clusters and deep invaginations of the ependymal wall, situated in the epithalamic area of the third ventricle of the rabbit have been precisely located by means of semithin serial sections. A study of these structures has been carried out using optical transmission and scanning electron microscopy. The round shaped supraependymal cell clusters revealed two types of cells: type I, of central location and bearing the morphological features of neurons and type II, located peripherically and of possible ependymary origin and nature. In the same epithalamic region, deep invaginations of the ventricular wall, lined by ependymal cells of similar morphology to those coating the rest of the third ventricle, are described. The functional role of both structures is discussed.