Question

The drawing shows two long rod-shaped structures with horizontal light and dark bands.

Answer 1

From my side I think it is Photoreceptors cells :

A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential.

There are currently three known types of photoreceptor cells in mammalian eyes: rods, cones, and photosensitive retinal ganglion cells. The two classic photoreceptor cells are rods and cones, each contributing information used by the visual system to form a representation of the visual world, sight. The rods are narrower than the cones and distributed differently across the retina, but the chemical process in each that supports phototransduction is similar. A third class of mammalian photoreceptor cell was discovered during the 1990s: the photosensitive ganglion cells. These cells do not contribute to sight directly, but are thought to support circadian rhythms and pupillary reflex.

hope u will like it...

Answer 2

The drawing shows two long rod-shaped structures with horizontal light and dark bands is Photoreceptors cells

• Photoreceptors are the cells in the retina that respond to light.
• Their unique feature is the presence of large amounts of tightly packed membranes that contains the photopigment rhodopsin or a related molecule.
• The tight packing is needed to achieve a high photopigment density, which allows a large proportion of the light photons that reach the photoreceptor which to be absorbed later.
• The photoreceptor’s output signal is contributed by photon absorption.
• In the retina of vertebrates the cones rods have photopigment-bearing regions (outer segments) composed of a large number of pancakelike disks.
• In rods the disks are closed, whereas in cones the disks are partially open to the surrounding fluid.
• In a typical rod there are about a thousand disks, and each disk holds about 150,000 rhodopsin molecules, 150 million molecules per rod.
• In most invertebrate photoreceptors the structure is different, with the photopigment borne on regularly arranged microvilli, fingerlike projections with a diameter of 0.1 μm.
• This photoreceptor structure is also known as a rhabdom.
• In both vertebrate rhabdoms and photoreceptors, each photoreceptor cell contains a nucleus, an energy-producing region with mitochondria (in the inner segment in rods and cones), and an axon that conveys electrical signals to the next neurons in the processing chain.
• In reptiles and birds the receptors may also contain colored oil droplets that modify the spectrum of the light absorbed by the photopigment, thereafter enhancing color vision.

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