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Schematic representation of a Euglena cell with red eyespot (9) Schematic representation of a Chlamydomonas cell with chloroplast eyespot (4). The eyespot apparatus (or stigma) is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids.
The eyespot is located near the cell equator. It is composed of a carotenoid-rich granule layer in the chloroplast which act like a light reflector. [6] The main function of the eyespot is the phototaxis, which consist of the movement (with the flagella) related to a light stimulus. [7]
The blood–ocular barrier is a barrier created by endothelium of capillaries of the retina and iris, ciliary epithelium and retinal pigment epithelium. [1] It is a physical barrier between the local blood vessels and most parts of the eye itself, and stops many substances including drugs from traveling across it. [2]
The movement of the eye is controlled by six distinct extraocular muscles, a superior, an inferior, a medial and a lateral rectus, as well as a superior and an inferior oblique. The superior ophthalmic vein is a sigmoidal vessel along the superior margin of the orbital canal that drains deoxygenated blood from surrounding musculature.
The vestibulo-ocular reflex is a reflex eye movement that stabilizes images on the retina during head movement by producing an eye movement in the direction opposite to head movement in response to neural input from the vestibular system of the inner ear, thus maintaining the image in the centre of the visual field. For example, when the head ...
Blood–air barrier – Membrane separating alveolar air from blood in lung capillaries; Blood–brain barrier – Semipermeable capillary border that allows selective passage of blood constituents into the brain; Blood–ocular barrier – Physical barrier between the local blood vessels and most parts of the eye itself
Wojnarowski underwent a physical in February and blood tests revealed his prostate-specific antigen (PSA) was elevated. An MRI did not reveal anything and a second PSA test remained high.
Eyespot (mimicry), a color mark that looks somewhat like an eye; Eyespot, a sensory organ of invertebrates; see simple eye in invertebrates; Eyespot, a type of eye in some gastropods, a part of sensory organs of gastropods; Eyespot apparatus, a photoreceptive organelle found in the flagellate (motile) cells unicellular photosynthetic organisms