Explanation:
For paleontologists, however, the Phylogenetic Species Concept is most frequently employed, simply because we just can't test reproductive isolation in fossil taxa.
The gaps (approximately 1 micrometer wide) formed between myelin sheath cells long the axons are called Nodes of Ranvier. Since fat serves as a good insulator, the myelin sheaths speed the rate of transmission of an electrical impulse along the axon.
Down syndrome, turner syndrome, Klinefelter syndrome, and fragile X syndrome.
