fertilization-+rebecca

sperm article:-

Sperm Article (1) What is a germ cell? (male germ cell and female germ cell) (2) Compare the size of a sperm to an egg. Insert a picture here comparing the sizes.
 * Sperm is the germ cell for males. and an egg is a germ for a female Germs are sex cells.
 * Sperm are fast, they have chubby teardrop heads and tapering tails. Sperm is the tiniest cell in the human body. The head of a mature, semen- ready sperm cell spans about 5 microns and two ten- thousandths of an inch, less that half the width of a white blood cell of a skin cell. The egg is one of the biggest cells in the body. At 30 times the width of a sperm, the egg is massive enough to be seen with the naked eye.

(3) Compare the number of eggs produced by human females to the number sperm produced by human males.
 * each testes generates more than 4 million new sperm per hour and a lifetime total of maybe 12 trillion sperm per man.

(4) Describe semen. What is the purpose of semen?
 * a viscous mix of sugars, citric acid and other ingredients designed to pamper and power the sperm cells and prepare them for difficult times ahead; the sperm proper account for only about 1 percent of the semen mass. Yet in that 1 percent may be found 150 million sperm, 150 million human aspirants yearning to meet their mammoth other halves.

(5) What can be wrong with sperm? What percentage of sperm are usually normal?
 * the majority of sperm couldn’t fertilize an ovum. “Only a perfectly normal sperm can penetrate an egg, and the majority of sperm are abnormally shaped. Some may have pinheads, others have two heads, some lack tails, a third don’t move at all. a man is lucky if 15 percent of his sperm are serviceable.

(6) Where do sperm develop? Why could a fever disrupt sperm production for months?
 * Creating sperm is a complex. It is a multistep operation where immature cells spend one or two months wending through a labyrinth of tubules coiled in the testes, at each stage losing a bit more of the blobby contours and yolky contents of standard cells and assuming the streamlined profile of sperm cells. Sperm must be performed at temperatures some 2 degrees below that of the body, which is why the testicles hang outside the body, where breezes can keep them cool; why a man hoping to become a father is advised to skip the hot baths and saunas; and why a bout of high fever can disrupt fertility for months.

(7) Describe in detail the three parts of a sperm cell.
 * Sperm - an insect, three basic body segments. The head, which is taken up largely by a supercondensed tangle of 23 chromosomes, half the complement of DNA found in a normal body cell and the right number to merge with an egg’s 23 chromosomes and begin tapping out a whole new body. At the tip of the sperm head is the acrosome, a specialized sack of enzymes that help the sperm penetrate through a male -the “forest” of ancillary cells and connective tissue that surrounds the ripe, ready egg.Below the head is the midpiece, which is packed with the tiny engines called mitochondria that lend the sperm its motility, and below the midpiece is the tail, a bundle of 11 entwined filaments that thrashes and propels a sperm forward at the estimable pace of one-twelfth of an inch per minute, the equivalent of a human striding at four miles an hour. Sperm do not really hit their stride until they are deposited in the female reproductive tract, at which point chemical signals from the vaginal and cervical mucus seem to spark them to life. Released from the buffering folds of their seminal delivery blanket, they at first swim straight ahead, torpedo-style, “with very little back and forth of the head, They may linger in the cervical mucus for a couple of days, or cross the cervix and enter the uterus.

(8) How do the sperm react to being in the female reproductive tract? How do they know where to go?
 * If an egg has burst from its ovarian follicle and been plucked by a fallopian tube, sperm can sense its signature, a telltale shift in calcium ions. The sperm become hyperactivated, switching to a crazed figure-eight motion ideal for boring through barriers. The ovum eggs them on, signaling some to play the sacrificial kamikaze and explode their enzyme sacks prematurely, loosening the corridor for other, shapelier sperm to pass through intact.

(9) How is the egg only fertilized by one sperm?
 * A few dozen fine-figured sperm find their way to the final barrier, the egg’s plasma membrane, where they waggle with all their crazy-eight might and beg to be chosen — but only one will be taken, will fuse with the egg and be absorbed into its rich inner sanctum.