Objective: To analyze morphological differences between the choroidal innervation of the human and the rabbit, the latter being a species frequently used as an experimental model of human ocular diseases. Methods: Twelve human and 12 rabbit choroidal whole mounts were processed using an indirect immunohistochemical technique, peroxidase-anti-peroxidase and antibodies against 200 kD neurofilament. Results: Choroidal nerve fibers were perivascular and intervascular. Perivascular fibers surrounded all arteries forming a network that was more developed in the rabbit. In humans, intervascular fibers were mainly concentrated at the posterior pole where they formed a denser and more highly organized plexus than in the rabbit, which did not exhibit a preferential location for these fibers. Human choroidal ganglion cells were far more numerous than in the rabbit and were concentrated in a circumferential area corresponding to the entrance of the short posterior ciliary arteries of the submacular area. In the rabbit, these cells were restricted to the peripheral choroid. Conclusions: Some differences were observed between human and rabbit choroidal innervation. The abundance of ganglion cells and their preferential distribution could be necessary to maintain a constant blood flow in the central area of the human choroid. The lack of organization of rabbit choroidal innervation at the posterior pole could be associated with an absence of the macula. These differences, along with peculiarities of retinal vascularization, should be taken into consideration when using the rabbit as an experimental model to study human eye diseases in which regulation of choroidal blood flow is involved.

Objetivo: Analizar las diferencias morfológicas entre la inervación coroidea del hombre y el conejo, especie frecuentemente utilizada como modelo experimental de enfermedades oculares. Método: Se estudiaron montajes planos de coroides (12 humanas y 12 de conejo albino) con la técnica de inmunohistoquímica indirecta de la peroxidasa-antiperoxidasa, utilizando un anticuerpo frente al neurofilamento de 200 kD. Resultados: Las fibras nerviosas coroideas pueden ser perivasculares e intervasculares. Las perivasculares rodeaban las arterias formando una red que estaba más desarrollada en la coroides del conejo. En el humano, las fibras intervasculares se concentraban principalmente en el polo posterior donde formaban un plexo más denso y organizado que en el conejo, el cual no tenía una localización preferencial. Las células ganglionares eran más numerosas en el humano, concentrándose en un área circunferencial correspondiente a la entrada de las arterias ciliares cortas posteriores y en el área submacular. En el conejo estas células se situaban sólo en la periferia. Conclusiones: Existen diferencias entre la inervación coroidea humana y del conejo. En el humano, la abundancia de células ganglionares y su distribución, podrían ser necesarias para mantener un flujo sanguíneo constante en el área central de la coroides. La falta de organización nerviosa en el polo posterior del conejo podría estar asociada a la ausencia de mácula. Estas diferencias, junto a las diferencias anatómicas de la vascularización retiniana, deberían ser tenidas en cuenta al utilizar el conejo como modelo experimental para estudiar enfermedades oculares en las que esté implicada la regulación del flujo sanguíneo coroideo.

Purpose: To compare findings of normal angles with those from primary congenital glaucoma in order to clarify the pathogenic mechanisms of the disease and to explain the success of surgical treatment in some of these patients. Methods: Adult normal eyes from cadavers and fragments of surgical trabeculectomies from patients with primary congenital glaucoma previously treated with goniotomy were studied. Eyes were processed for examination using light microscopy and scanning electron microscopy techniques. Results: The following was evident in congenital glaucoma: 1) high iris insertion; 2) no observable pre-trabecular membrane, but enlarged trabeculae with diminished inter-trabecular spaces; 3) Schlemm’s canal (SC) apparently normal, with vacuoles in the wall indicating normal functioning; 4) sectioning of the abnormal trabecular tissue during goniotomy allowed repositioning of the angle structures and hence the appearance of the angular recess. Conclusions: Anomalies of the trabecular structures in primary congenital glaucoma do not always parallel an abnormal development of the SC and the collector channels. This fact could explain the success of goniotomy in this type of glaucoma.

Objetivo: Comparar los hallazgos morfológicos observados en ángulos normales con los observados en ángulos de pacientes con glaucoma congénito primario, para intentar clarificar los mecanismos patogénicos de esta enfermedad, así como explicar el éxito del tratamiento quirúrgico en alguno de estos pacientes. Métodos: Se utilizaron ojos adultos normales procedentes de cadáveres y fragmentos quirúrgicos procedentes de trabeculectomías, de pacientes con glaucoma congénito primario que habían sido tratados previamente con una goniotomía. Los tejidos fueron procesados para su examen a microscopía óptica (MO) y microscopía electrónica de barrido (MEB). Resultados: En los glaucomas congénitos encontramos: 1) inserción alta del iris; 2) No se observa una membrana pre-trabecular, sino que comparando con los ángulos normales las trabéculas aparecen ensanchadas con disminución de los espacios inter-trabeculares; 3) el canal de Schlemm (CS) es aparentemente normal, con vacuolas en su pared que indican un funcionamiento normal del mismo; 4) la sección del tejido trabecular anormal que produce la goniotomía, permite el reposicionamiento de las estructuras del ángulo y por tanto la aparición del receso angular. Conclusiones: En el glaucoma congénito primario las anomalías de las estructuras trabeculares no siempre se acompañan de un desarrollo anómalo del CS y de los canales colectores. Este hecho podría explicar que la goniotomía sea un tratamiento con éxito en estos glaucomas.

Different from most mammalian species, the optic nerve of the rabbit eye is initially formed inside the retina where myelination of the axons of the ganglion cells starts and vascularization occurs. Astrocytes are confined to these regions. The aforementioned nerve fibers known as medullated nerve fibers form two bundles that may be identified with the naked eye. The blood vessels run on the inner surface of these nerve fiber bundles (epivascularization) and, accordingly, the accompanying astrocytes lie mostly facing the vitreous body from which they are separated only by the inner limiting membrane of the retina. The arrangement of the astrocytes around blood vessels leads to the formation of structures known as glial tufts. Fragments (N = 3) or whole pieces (N = 3) of the medullated nerve fiber region of three-month-old male rabbits (Orictolagus cuniculus) were fixed in glutaraldehyde followed by osmium tetroxide, and their thin sections were examined with a transmission electron microscope. Randomly located discontinuities (up to a few micrometers long) of the basement membrane of the inner limiting membrane of the retina were observed in the glial tufts. As a consequence, a direct contact between the astrocyte plasma membrane and vitreous elements was demonstrated, making possible functional interactions such as macromolecular exchanges between this glial cell type and the components of the vitreous body.