Retinal adaptation to dim light vision in spectacled caimans (Caiman crocodilus fuscus): Analysis of retinal ultrastructure.

It has been shown that mammalian retinal glial (Müller) cells act as living optical fibers that guide the light through the retinal tissue to the photoreceptor cells (Agte et al., 2011; Franze et al., 2007).

Corrigendum: Distribution of 28 kDa Calbindin-Immunopositive Neurons in the Cat Spinal Cord.

[This corrects the article on p. 166 in vol. 9, PMID: 26858610.

The ultrastructure of rabbit sclera after scleral crosslinking with riboflavin and blue light of different intensities.

Purpose: We aimed to determine the ultrastructural changes of collagen fibrils and cells in the rabbit sclera after scleral crosslinking using riboflavin and blue light of different intensities. Scleral crosslinking is known to increase scleral stiffness and may inhibit the axial elongation of progressive myopic eyes.

Methods: The equatorial parts of the sclera of one eye of six adult albino rabbits were treated with topical riboflavin solution (0.

Distribution of 28 kDa Calbindin-Immunopositive Neurons in the Cat Spinal Cord.

The distribution of vitamin D-dependent calcium-binding protein (28 kDa calbindin) was investigated in cat lumbar and sacral spinal cord segments (L1-S3). We observed specific multi-dimensional distributions over the spinal segments for small immunopositive cells in Rexed laminae II-III and medium-to-large cells of varying morphology in lamina I and laminae V-VIII. The small neurons in laminae II-III were clustered into the columns along the dorsal horn curvature.

[Development of Meynert cells in cat visual cortex under the conditions of flickering light stimulation].

To examine the effect of rhythmical light stimulation on postnatal development of the visual system, the formation of Meynert cells was studied in area 17 and posteromedial suprasylvian area (PMLS) of kittens reared under the conditions of flickering light stimulation (15 Hz frequency). Profile area of neuronal cell bodies and cytochrome oxidase (CO) activity level were measured in frontal sections of the visual cortex in control (n = 6) and stimulated (n = 6) kittens. Meynert cells located in area 17 and PMLS demonstrated an approximately 37% increase in CO activity in the stimulated animals.

[Changes of y neuron formation in cat visual system during early postnatal ontogenesis under the influence of binocular rhythmic light stimulation].

To examine the effect of an artificial rhythmic light stimulation on the development of structural and functional organization of Y neurons of cat visual system in the ontogenesis, the distribution of the neurons immunopositive to SMI-32 antibodies was studied in lateral geniculate nucleus (LGN) and posteromedial suprasylvian area (PMLS). Laminar distribution of SMI-32-positive neurons and neuronal body profile area were analyzed in intact animals (n = 4) and in kittens (n = 4) grown under conditions of rhythmic light stimulation with 15 Hz frequency for 4 months. In light-stimulated animals, changes in laminar distribution of immunopositive neurons were detected in both LGN (decline in the percentage of the immunopositive cells in C(M) layer) and in PMLS area (decrease in cell count in layer V).

Grouped retinae and tapetal cups in some Teleostian fish: occurrence, structure, and function.

This article presents a summary and critical review of what is known about the 'grouped retina', a peculiar type of retinal organization in fish in which groups of photoreceptor cell inner and outer segments are arranged in spatially separated bundles. In most but not all cases, these bundles are embedded in light-reflective cups that are formed by the retinal pigment epithelial cells. These cups constitute a specialized type of retinal tapetum (i.

Photonic crystal light collectors in fish retina improve vision in turbid water.

Despite their diversity, vertebrate retinae are specialized to maximize either photon catch or visual acuity. Here, we describe a functional type that is optimized for neither purpose. In the retina of the elephantnose fish (Gnathonemus petersii), cone photoreceptors are grouped together within reflecting, photonic crystal-lined cups acting as macroreceptors, but rod photoreceptors are positioned behind these reflectors.

Effects of intravitreal bevacizumab (Avastin) on the porcine retina.

Background: To evaluate the effects of intravitreal bevacizumab (Avastin) on the porcine retina, with respect to structural alterations, expression of proteins involved in apoptosis (bax, caspase-3, caspase-9) and gliosis (vimentin, GFAP), expression of factors which influence the development of vascular edema (VEGF, PEDF), and of membrane channels implicated in retinal osmohomeostasis (Kir4.1, aquaporin-1, aquaporin-4).

Methods: One eye of seven adult pigs received a single intravitreal injection of bevacizumab (1.

[Retinotopic organization of the lateral suprasylvian sulcus' posterior-medial area as revealed by analysis of the pattern of cortico-cortical connection with the cat 17th area].

Using cortico-cortical connection analysis technique, the cat visual area PMLS (the area located on posterior medial wall of the lateral suprasylvian sulcus) retinotopic organization was investigated. A retrograde axonal tracer: horseradish peroxidase (HRP), was injected in the PMLS, and initial neurons were investigated in area 17. It was shown that after HRP injection in PMLS locus, where a central vision field is located, a labelled cell pattern in area 17 corresponded to the L.

[Development of primary visual cortex connections with the motion processing center: the role of visual environment].

Development of axonal connections between cat primary visual area 17 and visual motion processing center was studied to investigate cortico-cortical connection plasticity in ontogenesis as affected by an experimental modification of visual environment (flickering light stimulation). By using a retrograde axonal labeling by horseradish peroxidase, a distribution of initial neurons in area 17 that send afferent projections to PMLS (posterior medial part of lateral suprasylvian sulcus) was analyzed. Sixteen 5-week-old and 12-14-week-old kittens, than were reared in normal visual environment or were subjected to a flickering light of 15 Hz frequency, were examined.

[Ontogenetic specifics of organisation of the cortico-cortical connections of the cat primary visual cortex and lateral suprasylvian area].

A quantitative and qualitative analysis of distribution of initial cells that organize the cortico-cortical connections between area 17 and posterior-medial lateral suprasylvian area (PMLS) was carried out in 10 kittens (5- and 12-week old). A horseradish peroxidase labeling technique was used. PMLS area is the highest center of moving visual stimuli information processing.

[Early ontogenetic development of regular organization of corticocortical connections between visual areas 17 and posteromedial lateral suprasylvian area in the cat].

Early ontogenetic development of cluster organization of corticocortical connections between visual areas 17 and posteromedial lateral suprasylvian area (PMLS) was studied in cat. Retrograde axonal tracer horseradish peroxidase was microinjected into the area PMLS. Labeled initial neuron distribution was analyzed in area 17 in 5- and 12-week-old kittens.

Effects of transient and prolonged flashing light stimulation on the cytochrome oxidase module system in layer IV of the primary visual cortex of kittens.

Cytochrome oxidase spots in layer IV of field 17 of the primary visual cortex were studied in kittens aged 33, 49, and 93 days, stimulated with a light flashing at a frequency of 15 Hz. The kittens of one group received stimulation from the moment of eye opening until euthanasia (prolonged stimulation); other groups received stimulation for eight days starting from ages 26, 42, or 85 days (transient stimulation), again until euthanasia. Both types of stimulation were found not to alter the geometrical characteristics of cytochrome oxidase spots, but led to significant increases in the contrast of spots located in the splenial gyrus.

[The area centralis of the mammalian retina: morphology and histogenesis].

This review summarises both classical and current literature data on the structure and the histogenesis of the retina of the mammalian eye and, in particular, of its specialized region--area centralis. The review describes the modem concepts of cytoarchitecture of area centralis, as well as the peculiarities of its blood supply, and presents the details of its histogenesis from early embryonic stages to postnatal development.

Involvement of the sacral parasympathetic nucleus in the innervation of the descending colon and rectum in cats.

Studies in anesthetized (urethane, 1.5 g/kg, i.p.

[Morpho-physiological features of the human eye sclera as the key unit in the level of intraocular pressure under normal conditions and in glaucoma].

The results of sclera investigations from the positions of morphology, physiology, biomechanics and control-system theory, are summarized. The morphological evidence was obtained supporting the physiological hypothesis stating that the specific anatomical organization and spatial displacement of elastic fiber-containing scleral layers against one another, are the key elements in formation of the individual level of intraocular pressure (IOP) in man both under normal and pathological conditions. It was shown that the elastic fibers outlined the collagen lamallae in of scleral internal layers.

[Participation of sacral parasympathetic nucleus in the innervation of the descending colon and the rectum in cats].

The localization and morphometric features of the preganglionic neurons of the spinal sacral parasympathetic nucleus innervating the descending colon and the rectum, were studied in cats, anesthetized with urethane (1.5 g/kg intraperitoneally) using the method of retrograde horseradish peroxidase transport. The solution of the marker was injected under the serosa of the indicated areas of the colon.

Dim light vision--morphological and functional adaptations of the eye of the mormyrid fish, Gnathonemus petersii.

The African weakly electric fish Gnathonemus petersii is well known for its electrosensory capabilities. These animals can detect and distinguish objects through active electrolocation in complete darkness. Because of their nocturnal lifestyle, a low contribution of vision for orientation and object detection has been expected.

Parasympathetic innervation of the initial segments of the large intestine in cats.

The locations and morphometric characteristics of efferent parasympathetic neurons in the dorsal motor nucleus of the vagus nerve and the cruciform parasympathetic nucleus of the spinal cord, innervating the area of the ileocecal sphincter and the ascending and transverse segments of the colon, were studied. Horseradish peroxidase solution was injected beneath the serous membranes of these parts of the intestine in urethane-anesthetized cats. After 48 h, animals were subjected to transcardiac perfusion with a fixative mixture and sections of the medulla oblongata and spinal cord were prepared and processed by the Mesulam method.

Some aspects of the modular organization of the primary visual cortex of the cat: patterns of cytochrome oxidase activity.

The distribution of the enzyme cytochrome oxidase (CO) in continuous series of parasagittal sections from field 17 and frontal sections of the dorsal nucleus of the lateral geniculate body (LGB) from normal kittens and adult cats was studied. In all cats apart from neonates, layer IV showed regularly alternating areas with above-background levels of CO activity ("spots"). There was a significant increase in the contrast of the "spots" from days 13 to 21, which was followed by a significant decrease from days 48 to 93.

[Effects of short-term and prolonged flickering on the system of cytochromeoxidase modules of the kitten primary visual cortex IV layer].

CO "spots" in layer IV of primary visual cortex were investigated in 33, 49 and 93-days kittens that were subjected to flickering light stimulation. Kittens from first group were stimulated since eye opening (long-term stimulation), other kittens--since postnatal day 26, 42 or 85 until euthanasia (short-term stimulation). Both types of stimulation did not disturb CO "spots" spatial organization but obviously increased a contrast of splenial CO "spots".

[Parasympathetic innervation of proximal parts of the colon in cat].

The localization and morphometric features of efferent parasympathetic neurons of the vagus dorsal motor nucleus and of the spinal sacral parasympathetic nucleus innervating the area of ileocaecal sphincter, ascending and transverse colon, were investigated. In urethane anaesthetized cats, the solution of horseradish peroxidase was injected under the serosa of the indicated areas of colon. In 48 hours animals were transcardially perfused with a fixative solution.

[Some aspects of modular organization of the cat primary visual cortex: cytochrome oxidase activity pattern].

Distribution of enzyme cytochrome oxidase (CO) activity was studied in a continuous series of parasagittal sections of cortical area 17 and frontal sections of dorsal lateral geniculate nucleus (LGNd) in kittens of different age and adult cats. In all the kittens except the newborns, in layer IV of area 17, regular alternating areas of CO activity, exceeding the background activity ("spots"), were detected. During the period between postnatal days 13 and 21 a significant increase of "spots" contrast took place, while between postnatal days 48 and 93 contrast was significantly decreased.