98 The Sex Check: A Study of Sex Chromatin in Human Cells II. SEX CHROMATIN AND
ID: 189144 • Letter: 9
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98 The Sex Check: A Study of Sex Chromatin in Human Cells II. SEX CHROMATIN AND NUCLEAR SEX Chromatin bodies resembling sex chromatin are occasionally observed in tissues taken from males. what appears to be sex chromatin in male cells normally ranges from abut 2% in oral snears to as high as 20% in liver preparations. In fact, for an acurate de emn nation of nuclear sex, a statistically significant number of cells must be examined and the percentage having sex chromatin computed. For oral smears made from females, most investigators find that be tween 50)% and 65% of the healthy cells demonstrate sex chromatin. Only normal-looking nuclei that stain evenly should be scored. Nuclei that are folded, have granulated nucleoplasm, or demonstrate any sign of degeneration cannox be included in a critical study of cells 1. Examine 50 squamous epithelial cells from a human female. How many exhabit sex chromatin? 2. What is the incidence of sex chromatin among 50 oral mucosal cells obtained from a human make? 3. Did you find any cells of the human female that appear to have more than one sex chromatin What percentage of these 50 cells reveal sex chromatin? body? TABLE 9.1 Sex Chromatin and Its Relationship to Sex Chromosome Complement and Chromosome Number Number of Sex Chromatin Bodies Observed in Somatic Cells Phenotypic Sex of Individual from Whom Cell Was Obtained Probable Sex Chromosome Complement Total Number of Chromosomes in Somatic Cells Male (normal Female (abnormal Male (abnormal) Female (normal) Male (abnormal Female (abnormal) Male (abnormal) Female (abnormal 4. For most mammals studied, and for humans in particular, evidence has accumulated to show that the Y chromosome is male determining and that, with rare exceptions, whenever it is present the Female-determining genes are apparently located on both the X chromosome and the autosomes. The normal human female has a somatic chromosome complement of 46, consisting of 44 autosomes and two X chromosomes, the normal male has 44 basis of this information, complete Table 9.1, phenotype of the individual will be male. indicating the probable sex chromosome complement and the total number of chromosomes antic- ipated in the somatic cells of the individual (assuming the presence of the normal 44 autosomes)Explanation / Answer
Number of sex chromatin bodies observed in somatic cell
Phenotypic sex of individual
Probable sex chromosome complement
Total number of chromosome in somatic cells
0
Male (N)
XY
46
0
Female(A)
X0
45
1
Male(A)
XXY
47
1
Female(N)
XX
46
2
Male(A)
XXXY
48
2
Female(A)
XXX
47
3
Male(A)
XXXXY
49
3
Female(A)
XXXX
48
Sex chromatid called as bar body, is present when one X chromosome remains inactivated. Hence in normal female one bar body will appear (as female has two XX chromosome, one X become inactivate), in case off male no bar body observe.
However in case of klinefelture syndrome in male (XXY) one sex chromatid/bar body will appear.
5.
a. female with 0 sex chromatid (X0) is a classical turner syndrome.
b. male having one chromatid body observed (XXY) is classical klinefelture syndrome.
c. female having 2 chromatid bodies (XXX) triple X chromosome are termed as a metafemale.
Number of sex chromatin bodies observed in somatic cell
Phenotypic sex of individual
Probable sex chromosome complement
Total number of chromosome in somatic cells
0
Male (N)
XY
46
0
Female(A)
X0
45
1
Male(A)
XXY
47
1
Female(N)
XX
46
2
Male(A)
XXXY
48
2
Female(A)
XXX
47
3
Male(A)
XXXXY
49
3
Female(A)
XXXX
48
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