Cells of human body: somatic and germ cells

Cells of human body

1. Somatic cells
2. Germ cells

Somatic cells of body  are three types:

•      Permanent cells: they do not divide in post natal life (after birth) . Ex: neuron

•       Labile cells are cells that multiply constantly throughout life. ex: epidermis of skin(replace within one month) , intestinal epithelium(replace daily) ,

•      Stable cells are cells that multiply only when needed. Ex : liver, skeletal muscle

Germ cells: are two types male and female germ cells

Female germ cell : Oocyte: the female germ or sex cell produced in the ovaries

•      Immature female germ cells : Oogonia/ Diploid /Chromosome number: 46 ( 44 autosomes+ XX)/At intrauterine life, they increase their number by mitosis  

•      Mature female germ cells: Ovum ( mature oocyte ) / Haploid/Chromosome number: 23 (22 autosomes + X) / After puberty upto menopouse, only one ovum is produced by meiosis in each month

Male germ cell:  Sperm: the male germ cell produced in the testes.

•      Immature male germ cells :  Spermatogonia /Diploid /Chromosome number: 46 ( 44 autosomes+ XY)/ At  puberty they start to increase their number by mitosis  and continued until death

•      Mature male germ cells : Spermatozoa / Haploid / Chromosome number: 23 (22 autosomes + X Or  22 autosomes + Y) / At  puberty they start to increase their number by meiosis &  continued until death