Biological differences between males and females are found in three ways:

• In chromosomes
• In hormones
• In structure of the nervous system

Hormones and chromosomes are the:

• Bases of masculinity and femininity
• Structural units and carriers of heredity
• Play important role in various human behaviors

Endocrine system is a network of glands that produce and secrete chemical messengers (hormones), directly into the blood stream. This activity is controlled by hypothalamus: the important relay station and significant brain structure.

Hormones and Chromosomes:

Hormones and chromosomes are not only bases of masculinity and femininity and structural units of heredity, they play important role in various human behaviors. Endocrine System is a network of glands that produce and secrete chemical messengers that are called hormones, directly into the blood stream. Theses glands are controlled by hypothalamus that is important relay station and significant brain structure. Pituitary glands (also called master glands) stimulate or inhibit secretion of hormones from other glands. Sex and reproduction hormones are called, Steroid hormones. Reproductive organs ovaries (in females) and testes (in males) are called gonads.

Sexual Differentiation and role of Chromosomes:

Sexual dimorphism is existence of two sexes (male & female) in a species, including differences in genetics, gonads, hormones, internal genitalia and external genitalia. The process of sexual differentiation starts when conception takes place. Chromosomes are threadlike structures that are structural carriers of heredity, play very important role in sex differentiation. In human beings there are 23 pairs of chromosomes. At the time of conception half amount of chromosomes is received from mother side and half from father side. 23rd pair of chromosome is called sex chromosome in females it is XX and in males it is XY. Genes contain genetic information carried on chromosomes. Researchers claim that XY chromosomal makeup may not be as stable as XX and therefore play a role in higher mortality rates for men. XX chromosomal makeup and the hormone estrogen seem to make women less vulnerable to physical problems so women live longer lives.

Sex Chromosomal Abnormalities:

Sudden structural changes in the genes are called mutations. These mutations lead to negative consequences in individual’s development. Some times deleted or duplicated number of chromosomes also causes abnormalities in an individual. Researches have found that disorders in sex chromosomes lead to problems in gender role development, intelligence, growth and hormone production.

Female Sex Chromosome Abnormalities:

Turner’s syndrome:

This syndrome occurs when individual inherit only one X chromosome and their sex chromosomal structure is XO.

Such cases are females in sex with abnormal growth patterns. They are short in stature, averaging 4 foot 7 inches as adults, and often have distinctive webbed necks (i.e., extra folds of skin), small jaws, and high arched palates. They generally lack prominent female reproduction ability.