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.
The chromosomes (really pairs of chromatids) split apart to form the genetic material of the four new cells. The end result is four sex cells each with a complete but single set of 23 chromosomes. On fertilisation the nuclei of the sperm and the egg join to form a new nucleus, called the zygote. The zygote contains 23 pairs of chromosomes â 23 single chromosomes from the sperm, and 23 single chromosomes from the egg. SUMMARY ANIMATION. For meiosis to work, first the chromosomes are doubled, just as they are for mitosis: