Sex determination in human – The course is designed for the basic understanding of anatomical structures and physiological functions of human body, musculoskeletal system, digestive system, respiratory system; cardiovascular system; urinary system, endocrine system, reproductive system, nervous system, hematologic system, sensory organs, integumentary system, and immune system.The aim of the course is to acquire knowledge and skills regarding anatomy and physiology.
Sex determination in human
A sex-determination system is a biological system that determines the development of sexual characteristics in an organism which depends on sex chromosomes of sex cells.
- The normal number of chromosomes in man is 44 autosomes which are ordinary chromosomes and in addition 2 sex chromosomes, making 46; a child receives 23 chromosomes from each parent.
- Sex chromosomes are called X and Y chromosomes.
- The female possess 44 autosomes plus 2 X chromosomes (44 + XX = 46).
- The male possess 44 autosomes plus 1 X and 1 Y chromosomes (44+ XY = 46).
- The sex is determined by only father of child because only the sperm carries Y chromosome and the
ovum contains 22 ordinary chromosomes and one X chromosome. - Thus 44 plus XX (two sex chromosomes), one X from mother and one X from father, produce a female.
- But 44 plus XY (two sex chromosomes), one X from mother and one Y from father, produce a male.
Sex is determined at the time of fertilization by the nature of the sperm that fertilizes the egg. Y-bearing sperms produce male zygotes. X-bearing sperms produce female zygotes. So, it is clear that the sex is determined by the father of the child, according to which of the 2 sex chromosomes (X or Y) he contributes.
(Ref: Ross & Wilson 9th /438 + K. Indu, 1″ ed,P-379-381 + P.Evelyn, 16th,P-321)
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