A medical procedure used to open a blocked artery. Appeal An appeal is the action you can take if you disagree with a coverage or payment decision made by Medicare, your Medicare health plan, or your Medicare Prescription Drug Plan.
A uniflagellar sperm cell that is motile is referred to as a spermatozoon, whereas a non-motile sperm cell is referred to as a spermatium. Sperm cells cannot divide and have a limited life span, but after fusion with egg cells during fertilization, a new organism begins developing, starting as a totipotent zygote. The human sperm cell is haploid, so that its 23 chromosomes can join the 23 chromosomes of the female egg to form a diploid cell. In mammals, sperm develops in the testicles and is released from the penis.
For example, in humans each sperm and each egg produced by meiosis has only 23 chromosomes, including one chromosome from each pair of homologous chromosomes. When an egg and sperm are united during fertilization, the resulting zygote has 23 pairs of homologous chromosomes, one in each pair from the egg and one from the sperm. Thus, the zygote has 46 chromosomes, and when the zygote undergoes mitosis to begin to form an embryo, each cell will have the normal number of 46 chromosomes.