Estudio morfológico de la retina de salmones (Salmo salar) / Morphological study of the retina of salmon (Salmo salar)

La retina de peces teleósteos como pez cebra, se ha transformado en un importante modelo para el estudio de la plasticidad neuronal y la neurogénesis. Se ha demostrado además que la retina experimenta cambios ontogenéticos para adaptarse a distintos medios ambientes durante su vida. Este estudio tiene como objetivo describir el desarrollo ontogenético de la retina del alevín de salmón desde la eclosión hasta la fase de juvenil. Se trabajó con 30 salmones divididos en tres grupos de 10. Grupo I: recién eclosionados, con saco vitelino y 18 mm de longitud. Grupo II: sin saco vitelino y 30 mm de longitud. Grupo III: 100 mm de longitud. Cinco alevinesde cada grupo fueron procesados según el protocolo de Hanken & Wassersug para medir los diámetros dorsoventral y nasal-temporal utilizando el cartílago que protege al globo ocular. Los restantes cinco ejemplares fueron seccionados con micrótomo Microm en forma seriada (5 µm) y procesados con técnica H&E/Azul de Alcián. Se midieron las capas de la retina en un microscopio óptico Zeiss, con cámara Powershot incorporada y con un software Image Tool 3.0. El Grupo 1 presentó grandes ojos pigmentados, con aspecto de copa óptica embrionaria, la retina está estratificada en capas. La Capa Nuclear Interna (CNI) mide 62±10 µm y la capa plexiforme interna (CPI) 10±2 µm. El Grupo 2 presenta cambios en el espesor de ellas. La CNI disminuye su espesor a 45±8 µm y la Plexiforme aumenta a 25±5 µm. En los peces juveniles del Grupo 3, la CNI alcanza el espesor mínimo (15±3 µm), por el contrario, la capa Plexiforme interna aumenta su espesor hasta alcanzar (70±10 µm). En los tres grupos estudiados observamos en la periferia de la retina una zona proliferativa germinativa, que corresponde a un remanente del neuroepitelio embrionario, responsable del crecimiento continuado de la retina. La retina de los salmones puede ser también un importante modelo para el estudio de la ontogenia, la plasticidad neuronal y la neurogénesis. Esta neurogénesis en la retina de peces facilita la reordenación celular a lo largo de la ontogenia, lo que potencialmente permite la optimización del sistema visual a los cambios en las demandas visuales. Este estudio puede ser de utilidad para facilitar el diagnóstico en las patologías de ojo en salmonicultura y también puede contribuir a conocer mejor la regeneración de tejidos. Por otro lado, con estudios posteriores, la neurogénesis de la retina de peces podría extrapolarse al tratamiento de enfermedades humanas con daño a nivel retineal, tales como glaucoma, desprendimiento de retina y retinopatía diabética.

The retina of teleost fish zebrafish, has become an important model for studying neuronal plasticity and neurogenesis. It was further shown that the retina undergoes ontogenetic changes to adapt to different environments during their lifetime. This study aims to describe the ontogenetic development of the retina of juvenile salmon from hatching to the juvenile stage. We worked with 30 salmon divided into three groups of 10. Group I: newly hatched with yolk sac and 18 mm in length. Group II: without yolk sac and 30 mm in length. Group III: 100 mm long. Five fry each group were processed according to the protocol of Hanken & Wassersug to measure dorsoventral and nasal-temporal diameters using the cartilage that protects the eyeball. The remaining five specimens were sectioned with a microtome Microm serially (5 µm) and processed with technical H-E / Alcian blue. The layers of the retina were measured on a Zeiss optical microscope with camera Powershot built and with Image Tool 3.0 software. Group 1 showed large pigmented eyes, looking embryonic optic cup, the retina is stratified in layers. The inner nuclear layer (CNI) measured 62±10 microns and the inner plexiform layer (CPI) 10±2 µm. Group 2 presents changes in the thickness of them. The CNI decreases in thickness to 45±8 µm and the plexiform increased to 25±5 µm. In juvenile fish of group 3, the CNI reaches the minimum thickness (15±3 µm), by contrast, the inner plexiform layer thickness increases up to (70±10 µm). In the three groups observed in the periphery of the retina one proliferative germinative zone, which corresponds to a remnant of the embryonic neural epithelium responsible for the continued growth of the retina. The retina of the salmon can also be an important model for the study of ontogeny, neuronal plasticity and neurogenesis. This retinal neurogenesis fish rearrangement facilitates cell along ontogeny, potentially allowing optimization of the visual system to changes in the visual demands. This study may be useful to help diagnose pathologies in eye salmon and can also contribute to better understand tissue regeneration. On the other hand, with later studies, fish's retinal neurogenesis could be extrapolated to the treatment of human retinal diseases, such us glaucoma, retinal detachment o diabetic retinopathy.

Leishmania, Babesia and Ehrlichia in urban pet dogs: co-infection or cross-reaction in serological methods?

INTRODUCTION: The present study was designed to assess the occurrence of co-infection or cross-reaction in the serological techniques used for detecting the anti-Leishmania spp., -Babesia canis vogeli and -Ehrlichia canis antibodies in urban dogs from an area endemic to these parasites. METHODS: The serum samples from dogs were tested for the Babesia canis vogeli strain Belo Horizonte antigen and Ehrlichia canis strain São Paulo by immunofluorescence antibody test (IFAT) and by anti-Leishmania immunoglobulin G (IgG) antibody detection to assess Leishmania infection. We used the following four commercial kits for canine visceral leishmaniasis: ELISA, IFAT, Dual Path Platform (DPP) (Bio Manguinhos(r)/FIOCRUZ/MS) and a rK39 RDT (Kalazar Detect Canine Rapid Test; Inbios). RESULTS : Of 96 serum samples submitted to serological assays, 4 (4.2%) were positive for Leishmania as determined by ELISA; 12 (12.5%), by IFAT; 14 (14.6%) by rK39 RDT; and 20 (20.8%), by DPP. Antibodies against Ehrlichia and Babesia were detected in 23/96 (23.9%) and 30/96 (31.2%) samples, respectively. No significant association was identified between the results of tests for detecting Babesia or Ehrlichia and those for detecting Leishmania (p-value>0.05). CONCLUSIONS: In the present study, we demonstrated co-infection with Ehrlichia or Babesia and Leishmania in dogs from Minas Gerais (Brazil); we also found that the serological tests that were used did not cross-react. .

Reduced occurrence of programmed cell death and gliosis in the retinas of juvenile rabbits after shortterm treatment with intravitreous bevacizumab

OBJECTIVE: Bevacizumab has been widely used as a vascular endothelial growth factor antagonist in the treatment of retinal vasoproliferative disorders in adults and, more recently, in infants with retinopathy of prematurity. Recently, it has been proposed that vascular endothelial growth factor acts as a protective factor for neurons and glial cells, particularly in developing nervous tissue. The purpose of this study was to investigate the effects of bevacizumab on the developing retinas of juvenile rabbits. METHODS: Juvenile rabbits received bevacizumab intravitreously in one eye; the other eye acted as an untreated control. Slit-lamp and fundoscopic examinations were performed both prior to and seven days after treatment. At the same time, retina samples were analyzed using immunohistochemistry to detect autophagy and apoptosis as well as proliferation and glial reactivity. Morphometric analyses were performed, and the data were analyzed using the Mann-Whitney U test. RESULTS: No clinical abnormalities were observed in either treated or untreated eyes. However, immunohistochemical analyses revealed a reduction in the occurrence of programmed cell death and increases in both proliferation and reactivity in the bevacizumab-treated group compared with the untreated group. CONCLUSIONS: Bevacizumab appears to alter programmed cell death patterns and promote gliosis in the developing retinas of rabbits; therefore, it should be used with caution in developing eyes.

Mobile phone radiations, possible disruptor to early retinal development

This study was conducted with an objective to investigate the effects of mobile phone induced radiations on retinal morphogenesis of chick embryo. Experimental Study. This study was conducted at Anatomy department, Regional Centre, College of Physicians and Surgeons Pakistan, Islamabad from Jan. 2006 to Jan. 2007. Chicken embryos were exposed to mobile phone silent mode ringing by placing a GSM operated phone in the centre of the fertilized eggs developing in the incubator. This phone was ringed upon for 15 minutes twice daily for one experimental subgroup and 25 minutes twice for the other subgroup. The control and experimental groups were sacrificed at the end of 10 post incubation days. The retinae of the embryos were dissected out and statistically compared for the heights of different retinal layer after paraffin processing of sections. For lower dosage [15 minutes of ringing] of mobile phone induced EMFs. Thickness of the rods and cones layer and inner plexiform layer of the treated subgroup was significantly less than the control. On increasing the dosage to 25 minutes, thickness of the pigment epithelial layer of the treated group was significantly more than the control group. All the other layers were more in thickness in this subgroup but this difference was not statistically significant. The results of the study conclude that mobile phone radiations have a dose dependant regulatory effect on the early developmental process of chick embryo retina. EMFs dose Mobile phone induced EMFs disrupt the developmental process of embryonal retinogenesis. This effect is influenced differently at different levels exposure

Effect of experimentally induced hypothyroidism during pregnancy and lactation on the retina of juvenile and adult albino rats and the possible role of thyroid hormone supplementation

Nervous system growth and differentiation are closely correlated with the presence of thyroid hormones in initial development stages. Hypothyroidism during the fetal and postnatal life results in an irreversible mental retardation syndrome. At the cellular level, T3 is known to act on neuronal, neuroretinogenesis, and glial lineages. In this study, we aimed to study the influence of hypothyroidism on retinal development in juvenile and adult rats and the effects of thyroid hormone supplementation on both periods of development. This study was conducted using 56 male albino rats. They were divided into three groups: group 1 [control group] included 24 animals, group 2 [juvenile group] included 16 animals whose mother received carbimazole [NeoMercazol] antithyroid drug at a dose of 0.02 mg/day/pregnant female during gestation and lactation, this group was further subdivided into subgroup 2a [hypothyroid juvenile animals] and subgroup 2b [thyroid hormone-supplemented juvenile animals], and group 3 [adult group] included 16 animals, this group was also further subdivided into subgroup 3a [hypothyroid adult animals] and subgroup 3b [thyroid hormone-supplemented adult animals]. At the end of the experiment, the animals were killed. Retinal specimens from all groups were processed for light and electron microscopic studies. Biochemical analysis was carried out to measure the serum levels of triiodothyronine, T4, growth hormone, and insulin growth factor-1. In addition, estimations of lipid peroxidation, catalase activity, and antioxidant enzymes were made. Statistical analysis was carried out to measure the retinal thickness. Light and electron microscopic studies showed that thyroid hormone deprivation altered the organization of the retina in juvenile and adult rats. These changes were apparent in the form of significant reduction in the retinal layer thickness. In addition, degenerative changes in some layers were observed. The group with thyroid hormone supplementation showed recovery of both structural changes and retinal thickness, this recovery was apparent in the juvenile group. Adult animals showed minimal recovery. Biochemical analysis of the serum of hypothyroid animals showed a significant increase in lipid peroxidation products and decease in the serum levels of antioxidants, growth hormone, and insulin growth factor-1, comparable with the controls. Administration of thyroid hormone significantly restored their levels especially in the juvenile group. Gestational and lactational hypothyroidism induced marked changes in the developing retina in juvenile and adult rats. These changes were mostly normalized by thyroid hormone administration especially in the juvenile group

Ultraestructura de la retinopatía causada por la hiperoxia en ratas en desarrollo / Ultra structure of retinopathy induced by hyperoxia in developing rats

In order to evaluate the effect of postnatal hyperoxia on retinal structure, newborn rats were exposed to different oxygenation intervals (80 ± 1%) with three interruptions of 21% (30 min each). Four groups of rats were exposed from birth to the 6th, 9th, 12th and 14th postnatal day, respectively and another group was placed under normoxia. After this period all oxygenated groups and the controls remained under normoxia until they were 30 days old for the structural analysis of retina. Retinal histology was carried out using conventional techniques for transmission electron microscopy (TEM). In the ganglion cell layer of the retina from rats exposed for 9 days to hyperoxia, capillaries with large projections toward the lumen, were observed as a possible consequence of cellular edema of endothelium. The most severe damage was observed in rats exposed to hyperoxia during 12 and 14 days, showing mitochondrias swollen up and without crests in the areas surrounding the capillaries, necrosis and apoptosis processes, dense bodies, cells with swollen cytoplasms and rupture of the plasmatic membrane. The results suggest that postnatal hyperoxia causes severe damages to the retina in developing rats with a direct relationship between the time exposed to oxygen and ultra structural damages.

Con el propósito de evaluar el efecto de la hiperoxia posnatal sobre la estructura retiniana se analizaron retinas de ratas recién nacidas expuestas a diferentes periodos de oxigenación (80 ±1%), con tres interrupciones de 21% (30 min c/u). Cuatro grupos de ratas fueron expuestas desde su nacimiento hasta el 6to, 9no, 12mo y 14to días de vida y otro grupo fue mantenido en normoxia. Después de este periodo tanto los grupos expuestos a la hiperoxia como los controles permanecieron en normoxia hasta una edad de 30 días para el análisis estructural de la retina. La histología se hizo usando técnicas convencionales para microscopía electrónica de transmisión (MET). En la capa de células ganglionares de la retina de ratas expuestas a nueve días de hiperoxia, se observaron capilares con notables proyecciones hacia la luz, posiblemente como consecuencia de edema celular del endotelio. El daño más intenso fue observado en las ratas expuestas a hiperoxia durante 12 y 14 días, mostrando mitocondrias hinchadas y sin crestas en las áreas circundantes a los capilares, procesos de necrosis y apoptosis, cuerpos densos, células con citoplasmas hinchados y con ruptura de la membrana plasmática. Los resultados sugieren que la hiperoxia posnatal causa graves daños a la retina en las ratas en desarrollo, con una relación directa entre el tiempo de exposición al oxígeno y los daños ultraestructurales.

Nuclear exclusion of transcription factors associated with apoptosis in developing nervous tissue

Programmed cell death in the form of apoptosis involves a network of metabolic events and may be triggered by a variety of stimuli in distinct cells. The nervous system contains several neuron and glial cell types, and developmental events are strongly dependent on selective cell interactions. Retinal explants have been used as a model to investigate apoptosis in nervous tissue. This preparation maintains the structural complexity and cell interactions similar to the retina in situ, and contains cells in all stages of development. We review the finding of nuclear exclusion of several transcription factors during apoptosis in retinal cells. The data reviewed in this paper suggest a link between apoptosis and a failure in the nucleo-cytoplasmic partition of transcription factors. It is argued that the nuclear exclusion of transcription factors may be an integral component of apoptosis both in the nervous system and in other types of cells and tissues

Estudo da espessura foveal e perifoveal em indivíduos normais por meio do analisador de espessura retiniana / Foveal and perifoveal thickness in normal persons with the Retinal Thickness Analyzer

Objetivos: Avalliar um novo método de análise da retina no pólo posterior com o Analisador de Espessura Retiniana (Retinal Thickness Analizer - RTA). Estabelecer os valores da espessura retiniana na mácula de pacientes brasileiros normais. Pacientes e métodos: Foram analisados 35 olhos normais, estabelecendo-se a média da espessura retiniana na mácula, medida pelo RTA. Os valores encontrados para cada paciente foram correlacionados com a idae e sexo. Resultados: A espessura foveal média foi de 156µ, e a espessura perifoveal média foi de 191µ, näo houve Correlaçäo entre espessura retiniana näo invasivo, de simples execuçäo e boa reprodutibilidade, que poderá ser útil na análise de portadores de maculopatias. Estabeleceram-se os valores normais da espessura retiniana para uma populaçäo brasileira. Esses valores seräo úteis para uma avaliaçäo comparativa da espessura retiniana em situaçöes patológicas

Effect of ethambutol on the development of the retina and optic nerve of the chick embryo

The present work was concerned with the development of the retina and optic nerve of the chick embryo and the effect of ethambutol on its development together with the explanation of the possible hazards of antituberculous drugs which May occur To the foetus, if the pregnant mother is under the treatment with these drugs. Histological studies were made on the retina and optic nerve of 9,11 and 15 days chick embryos injected on the 6 th day of incubation with a dose of ethambutol equivalent to the human therapeutic dose [0.8mg/chick embryo]. It was found that ethambutol induced retardation of growth and degenerative changes in the layers of the retina associated with reduction in the size of the optic nerve. As age advenced at 15 day of incubation, regeneration of retina started and progressed gradually till full term, but its size was still less than the control embryo of the same age

Effect of X-radiation on the morphogenesis and histogenesis of the developing retina of the chick embryo

Morphological and histological studies were done on the retina of 10, 12 and 15 days chick embryos which were exposed to X-irradiation [1000 R at 200 k.v.] 48 hours after incubation. Retardation of growth of the retina was observed in 10 and 12 days treated chick embryos as evidenced by reduction of the size of the retina associated with disappearance of some layers of the retina. The retina of irradiated embryos showed signs of incomplete regeneration when these embryos were examined on the 15th day of incubation

Axon orientation and axo-dendritic polarity of retinal ganglion cells during postnatal development in the rat

The axon orientation and axo-dendritic polarities of ganglion cells were investigated in the retinae of developing and adult rats labeled with retrograde tracers. The cells were classified as either regular, if both parameters corresponded to those found among the majority of ganglion cells in the retina of adult rats, or irregular, if either axon orientation or axo-dentritic polarity, or both to follow the norm of adult retinae. The number of regular cells declined from 118,000 to the adult value of 63,000 during the first 5 days following birth, while the number of irregular cells remained stable at 90,000-100,000 during this period and declined thereafter to 46,000. These data suggest that the geometry of neurites within the retina affect the selective elimination of ganglion cells during postnatal development in rats

Developmental changes in synapses of the retino-recipient layers of the opossum superior colliculus

Changes in synaptic structure were examined in junctions of the retino-recipient layers of the opossum superior colliculus (SC) at critical developmental stages (30, 40 and 61 dai-old pouch young and adult controls). Criteria of classification were the presence and direction of curvature (smile, flat, frown and irregula) and the degree of aggregation of paramembranous components vis-a-vis curvature in the assessment of maturational changes

The development of the retinal projection to the olivary pretectal nucleus in normal and monocularly enucleated hamsters

The projection to the olivary pretectal nucleus (OPN) from the contralateral eyes is observed on the first day after birth and appears adult-like on postnatal day 5. The ipsilaeral projection is present at postnatal day 4, and expands to fill the nucleous overlapping the contralateral projection, though never as dense, between days 6 and 8. Then, in normal hamsters, ipsilaterally projecting fibers retract to the ventral side of the OPN by day 10. However, the dense expanded projection in the dorsal OPN ipsilateral to the remaining eye in monocularly enucleated hamsters persists adulthood