Читать книгу Horse Genetics - Ernest Bailey - Страница 60

The behavior of chromosomes through cell life cycles is the key to the principles of Mendelian inheritance. Two types of division cycles are characteristic of vertebrates. The first process (mitosis) occurs in all cells of the body. The second chromosome process (meiosis) is directly involved in the formation of the gametes (sperm and eggs) and occurs only in the reproductive organs or gonads (testes in males and ovaries in females).

In Fig. 4.4, the large mass to the right of the image is a large, intact nucleus. The smaller, dark staining bodies are chromosomes which have burst from another cell’s nucleus. Each contains tightly coiled DNA from one of the 64 horse chromosomes. All chromosomes participate in mitosis and meiosis. Two of the chromosomes are called “sex chromosomes” and are involved in gender determination. The remaining chromosomes are called autosomes. Chromosome (Cytogenetic) studies are described further in Chapter 17.