Question

Sex chromatin are present in
A. Drum stick like in lobe of neutrophil
B. Drum stick like in lobe of basophil
C. Drum stick like in lobe of eosinophil
D. Drum stick like in lobe of lymphocyte

Answer 1

Hint: Allosomes of the human female is XX whereas that of the human male is XY. As females contain 2 copies of the same chromosome, to avoid duplication of genes, one of the X chromosomes is randomly inactivated. This inactivated chromosome is called the heterochromatin or sex chromatin.

Complete answer:
Chromatin is composed of DNA and histones. It is located inside the nucleus and stained with basic dyes. Sex chromatin also called the Barr body is a mass of inactivated X chromosome in cells of normal females. The number of sex chromatin is one less than the number of X chromosomes. Thus in normal males(XY) and females with Turner syndrome(XO), sex chromatin are absent. X-inactivation is random in placental mammals but paternal-derived X chromosome is specifically inactivated in the case of marsupials.
The inactivated X chromosome is silenced and packed into a transcriptionally inactive structure called the heterochromatin. Heterochromatin can either be constitutive or facultative. These have specific functions. They can consist of genetically inactive satellite sequences or may either be centromeres and telomeres.
Neutrophils have a lobed nucleus. The sex chromatin is found as a drumstick shaped mass on one of the lobes of the neutrophil nucleus. There are structural differences in the nuclei of blood cells but sex chromatin is only found in the neutrophils.

Hence, the correct answer is option (A).

Note: Sex determination is illegal in our country. However, blood cells can be used for the sex determination test. Blood is collected in vacuiners containing EDTA and stained with specific dye and observed under a microscope for the presence of Barr bodies.