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Aerenchyma in stem cross section of a typical wetland plant. Aerenchyma or aeriferous parenchyma [1] or lacunae, is a modification of the parenchyma to form a spongy tissue that creates spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases between the shoot and the root. [2]
He observed "lacunae" (empty spaces) in the deep brain structures after occlusion of 200–800 μm penetrating arteries and connected them with five classic syndromes. These syndromes are still noted today, though lacunar infarcts are diagnosed based on clinical judgment and radiologic imaging.
Basically, the Retinal Vessel Analyzer measures the diameters of small arteries and vein in the posterior segment of the eye. In static retinal vessel analysis this is a snapshot, in dynamic vessel analysis (DVA) a 12.5 Hz optoelectric flickering light induces a stimulation of a specific segment of the retina to which the vessels react by a ...
If the lacunae are located in the macula, they affect acuity. Other types of eye abnormalities are also common, such as one eye being smaller than normal (microphthalmia), changes in the optic nerve, and incomplete closure/slitting of the membranes of the eye . Rapid, involuntary eye movements are common. Since people with Aicardi syndrome have ...
The uvea (/ ˈ j uː v i ə /; [1] derived from Latin: uva meaning "grape"), also called the uveal layer, uveal coat, uveal tract, vascular tunic or vascular layer, is the pigmented middle layer of the three concentric layers that make up an eye, precisely between the inner retina and the outer fibrous layer composed of the sclera and cornea.
Several layers such as the neural tube, neural crest, surface ectoderm, and mesoderm contribute to the development of the eye. [2] [3] [4] Eye development is initiated by the master control gene PAX6, a homeobox gene with known homologues in humans (aniridia), mice (small eye), and Drosophila (eyeless). The PAX6 gene locus is a transcription ...
The human eye is a sensory organ in the visual system that reacts to visible light allowing eyesight. Other functions include maintaining the circadian rhythm, and keeping balance. Arizona Eye Model. "A" is accommodation in diopters. The eye can be considered as a living optical device.
Thus if the central retinal artery gets occluded, there is complete loss of vision in that eye even though the fovea is not affected. The entire retina (with the exception of the fovea) becomes pale and swollen and opaque while the central fovea still appears reddish (this is because the choroid color shows through).