Your "blind spot" or the spot where the optic nerve exits the eye and goes the brain. Since it has to be a hole for the nerve to got through it, you can't see anything at that spot. Your brain takes the images around that spot and meshes it together so you can't tell that you have a blind spot.
photosensitive alloy containing silicon
The thoracic region of the spinal cord lacks autonomic preganglionic neurons. Autonomic preganglionic neurons are found in the intermediolateral cell columns of the spinal cord at the thoracolumbar (T1-L2) and sacral (S2-S4) levels.
cell wall
The incipient nucleus of a prokaryotic cell is called the nucleoid. It is a region within the cell where the genetic material is located, but it lacks a membrane-bound nucleus found in eukaryotic cells.
The mature red blood cell lacks a nucleus, and so is unable to reproduce.
cell wall and chloroplast
Retina
The Jyplostic Retina
Rods function in dim light and provide black-and-white vision. Cones support brighter daytime vision and the perception of color. A third type of photoreceptor, the photosensitive ganglion cell, causes reflexive responses to bright daylight.
A Mitochondrion
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prokaryotic cell =)