Cytogenetics is an independent branch of the doctrine of heredity, which examines different, first of all observed (explicate) carriers, containing the information on genetic inheritance.These chromosomes are the carriers of different types (polytene, mitotic and meiotic), plastids, interphase nuclei, and, to a lesser extent - the mitochondria.
On this basis, cytogenetic method is a set of methods and techniques study, first of all, the chromosomes in which they set the quantitative parameter is made of chemical and biological description, study the structure and modes of behavior during cell division.The scientific objective of this study is to establish the connection between the nature and the dynamics of changes in the structure of chromosomes and the picture of the variability of symptoms.
One of the most important areas of research that suggests cytogenetic method is to analyze the human karyotype.This study is usually carried out on cultures in which there is division of germ and somatic cells.
most common culture for this kind of research - peripheral blood cells, such as lymphocytes, fibroblasts and bone marrow cells.The most affordable of crops used in the medical cytogenetics are blood lymphocytes.The reason for this is that, as a rule, they are the subject of the analysis and in the postnatal period.In the analysis of fetal karyotype Cytogenetic method involves the use of cell cultures, the choice of which is due to several factors.Chief among these is the gestational age.For example, with less than 12 weeks, cytogenetic analysis of chromosomes is best done with the participation of the chorionic cells, and when pregnancy is over 12 weeks, it is advisable to consider the study of fetal cells.For this purpose, they are specifically allocated from the placenta and fetal blood.
cytogenetic karyotype to establish a method for studying heredity requires obtaining a blood sample in an amount of not less than 1-2 ml.Thus the method involves conducting research, consisting of three main phases:
- isolating and culturing the cells, which will be analyzed;
- staining;
- a thorough analysis of the preparation under the microscope.
effective cytogenetic method of genetics can be only when the following conditions are met.Firstly, it should be a certain number of cells in the metaphase stage.Second, the cultivation must be carried out in strict compliance with established rules and for a period of not less than 72 hours.Thirdly, the fixation of the cells should be performed with a solution of acetic acid and methanol simple ratio of these three substances: 1. In step
staining for cytogenetic study of color selection is made in view of the purpose of the study, i.e., what type of mutations should be studied.Most often, a continuous dyeing method is used, as it is the easiest to quantify the chromosomes.Modern research has most used the method of staining to determine the karyotype abnormalities in their quantified.But this cytogenetic method makes it impossible to determine and to identify the structural dynamics of chromosomes.Therefore, use other special methods that allow you to neutralize the lack of a continuous dyeing method.The most common of these, such as differential staining method, G-method, R-method and other.
Finally, the third stage of the research consists in the microscopic study of stained chromosomes are in the metaphase stage.During a set number of normal and abnormal in their body cells of the human fetus.For this purpose, as a rule, the analysis of several tissue.
