- The human body has a total of 210 different cell types; however, there are only three basic processes by which these cell types reproduce. The majority of cells in the body are classified as somatic cells. Somatic cells make up the skin, hair and muscle tissues. They reproduce through a process called mitosis, which is the most common form of cell replication. Mitosis can happen when areas of the body is growing, when older cells are replaced or when an area of the body becomes damaged or injured.
Mitosis takes place when a cell duplicates its genetic material and then splits in half to form two complete cells that are identical to the original one. The entire process takes anywhere from an half hour to an hour and a half depending on the type of cell involved. Overall, somatic cells are designed to reproduce up to 50 to 60 times within a person's lifetime before they die off. However skin, hair and nail cells reproduce many more times than 60. The actual rate of reproduction for hair, skin and nail cells depends on individual body chemistry.
Meiosis is a different process of cell reproduction that's specifically carried out by the reproductive organs. The results of meiosis are male gametes and female ovum, which are the cells that combine during conception. In males, gametes--or sperm cells--contain the chromosome material that's passed on to the offspring. And while body cells carry a total of 46 chromosomes, gamete cells carry only 23 chromosomes. A healthy young adult male will produce several hundred million gamete cells on a daily basis.
In females, sex cell--or ova--development follows a lengthy process, starting as early as the fifth month after a female is conceived. Meiosis begins at this stage, but stops at a precursor egg cell stage--or primary oocyte--during fetal development. Once a female hits puberty, hormonal secretions trigger the production of one or more ovum per month. After a period of time, the secondary oocytes, which are the mature eggs, are released from the ovaries. The process of complete meiosis in the female doesn't actually occur until an egg is fertilized by a gamete. As with the male gamete, only 23 of the female's 46 chromosomes are transferred to a zygote cell, which is the first form a fetus takes.
Upon conception, the development of a fetus into a baby is by far the most comprehensive and diverse process of cell reproduction. The zygote cell contains 46 chromosomes--half from the gamete and half from the ova. This is the same number of chromosomes that each respective parent carries. This same cell multiples into two groups of cells that make up an inner core and an outer shell. This formation is called a blastocyst and is considered the second stage of embryo development. The actual embryo is contained inside the shell.
Once the blastocyst enters the uterus, it becomes attached to the uterine wall and from there is nourished via the mother's bloodstream. Over the course of nine months, the zygote cell differentiates into the different cell types that make up the human body. This development unfolds according to the genetic markers contained inside its chromosome materials. The resulting newborn baby is the result of millions of cells reproducing to form the organs, tissues, muscles and skin cell groups.
previous post