Disc Shedding
The retina contains two types of photoreceptor – rod cells and cone cells. There are about 6-7 million cones that provide color vision to the eye, and they are very concentrated in a central spot in the retina, called the macula. However, the rods are much more numerous – they weigh in at about 120 million – and are also more sensitive than the cones. These rods are responsible for scotopic (night) vision, our most sensitive motion detection, and our peripheral vision. Vertebrate photoreceptors are composed of a photosensitive outer segment, an inner segment that contains the cell’s metabolic machinery (endoplasmic reticulum, Golgi complex, ribosomes, mitochondria), and a synaptic terminal at which contacts with second-order neurons of the retina are made. The photosensitive outer segment is connected to the inner segment by a modified, nonmotile cilium, and consists of a series of discrete membranous discs that are apparently derived from the plasma membrane in the region of the connecting cilium.
Read more about Disc Shedding: Formation and Shedding, Traditional Theories About The Mechanism of Disc Shedding, Recent Research About The Mechanism of Disc Shedding
Famous quotes containing the words disc and/or shedding:
“Perhaps all music, even the newest, is not so much something discovered as something that re-emerges from where it lay buried in the memory, inaudible as a melody cut in a disc of flesh. A composer lets me hear a song that has always been shut up silent within me.”
—Jean Genet (1910–1986)
“Thus Winter falls,
A heavy gloom oppressive o’er the world
Through Nature shedding influence malign,
And rouses up the seeds of dark disease.
The soul of man dies in him, loathing life,
And black with more than melancholy views.”
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