The word 'somatic' is from a Greek word soma, which means 'body'. Somatic cells are those that make up an organism, except for the germ cells. Sexually reproductive cells, that is, eggs and sperms in mammals, are called germ cells. They are present in each and every part of the body. They contain the same DNA throughout, and germ cells are made up of half the amount of DNA present in these. All the cells in the body of mammals, including humans, are made up of the gametocytes and undifferentiated stem cells, which is a somatic or diploid cell. Somatic cells make up the skin, bones, blood, connective tissues, etc.
Genetics and Chromosomal Content
As explained earlier, all cells except sex cells are known as somatic cells of the body. This means, a broader definition of the cells is non-sex cells. The human body contains 46 individual chromosomes. These chromosomes are divided into 23 pairs of chromosomes. Each of the chromosome pair has one chromosome that is inherited by the father and one from the mother. The number of chromosomes are twice the number of chromosomes in the sex cells. The latter contain only 23 chromosomes. After conception, the sex cells fuse together to create a zygote. The chromosome that the gametic cells contain, that is, X or Y chromosome, help determine the sex of the child. As they fuse together, they form a zygote with 46 chromosomes, that is, 23 pairs.
Humans and many other mammals have chromosomes arranged in pairs, and therefore, they are known as 'diploid' organisms. Sex cells contain single unpaired chromosomes called haploid. Many other species have chromosomes arranged in fours called tetraploid, and some have six pairs of chromosomes called hexaploid.
With the advancement in molecular biology and genetics engineering, scientists have been able to develop identical genetic clone of an animal. This is possible by 'somatic cell nuclear transfer', where the nucleus from a somatic cell (mostly skin cell) is removed. This nucleus is then injected into an ovum of the same species that has its genetic material removed. This ovum is then implanted into the uterus without fertilization, as it already contains the diploid number of chromosomes. The baby developing in the uterus will have the exact genetic material as the parent. The most successful cloning process so far has been of Dolly the Sheep. Scientists have also been able to clone a dog called Snuppy.
The presence of these cells in milk are an indication of cow udder infection―mastitis. Human genetics is a vast subject, that covers the depths of the tiniest of the cells and genetic materials of organisms.