The inheritance of genes contained in the cytoplasm of a cell, rather than the nucleus. Only a very small number of genes are inherited in this way. The phenomenon occurs because certain organelles, the mitochondria and (in plants) the chloroplasts, contain their own genes and can reproduce independently. The female reproductive cell (the egg) has a large amount of cytoplasm containing many such organelles, which are consequently incorporated into the cytoplasm of all the cells of the embryo. The male reproductive cells (sperm or pollen), however, consist almost solely of a nucleus, and any male organelles, e.g. mitochondria or mitochondrial DNA, are eliminated from the fertilized egg. Cytoplasmic organelles are thus not inherited from the male parent, and the DNA in plastids and mitochondria follows a pattern of strictly maternal inheritance, rather than Mendelian inheritance. In plants, male sterility can be inherited via the cytoplasm.