Sexual Development

SEXUAL DEVELOPMENT

Development of sex organs:  The physical and sexual development takes place more or less at the same time during puberty. The sex organs of boys and girls start developing. Testes in boys mature. They start producing semen. In girls, the reproductive organs are strengthened. The ovaries enlarge and the production of ova begins. The ovaries release mature ova. The girls start their monthly menstruation.

Development of secondary sexual characters: The development of secondary sexual characters also takes place. It starts in boys with the appearance of public and facial hair. In girls, the breasts start developing and the appearance of public hair takes place. Body hairs also become prominent.

Change in hormonal balance: Most of the changes that occur in adolescents are controlled by hormones. Hormones are the chemical substances produced and secreted by the endocrine glands. Hormonal balance in adolescents shifts strongly towards an adult state. This is triggered by the pituitary gland. Pituitary secretes hormones which influence the production of testosterone from testes in boys and estrogen and progesterone from ovaries in girls. These hormones are released into the blood stream and start the rapid maturation of the gonads (sex organs).

The reproductive phase in human beings: Humans become capable of reproduction when their testes and ovaries begin to produce gametes- the sperms and ova. The males produce gametes for a longer duration in their life as compared to females. In females, the ovaries become active when the girl reaches puberty, i.e. between 11-13 years of age. One ovum in one of the ovaries becomes mature once in about 28 days. The mature ovum enters the oviduct where it may get fertilized. If fertilized, it develops and reaches the uterus that is a pear- shaped structure present between the ovaries. Uterus is muscular and elastic and can grow, stretch and expand many times its size when the foetus grows and develops inside it.

Before the embryo enters the uterus, the uterus prepares itself to receive it by forming a thick lining of blood vessels. If fertilization does not occur, the egg disintegrates and the lining of blood vessels is shed off. This process of blood flow is termed as menstruation. It lasts 3-6 days. The first menstrual flow that begins in a girl at puberty is termed menarche.

The menstrual cycle stops when the woman is 45-50 years of age. This is termed menopause. In general, menstruation occurs regularly at intervals of 28-30 days. However, this period is variable. It may take about 6 months to one year for a girl’s menstrual periods to become regular, but this should not cause any worry. If the ovum is fertilized by the sperm, a zygote is formed that begins to divide and gets embedded in the uterus for further development.

Sex hormones control the onset of puberty and initiate the reproduction dunction. Body changes in male such as the growth of facial hair and cracking of voice, are initiated due to the secretion of testosterone. Body changes in females during puberty, such as brest development, are initiated by estrogen. During puberty, the tests begins to secrete the testosterone hormone. This hormones bring about the physical changes that make a boy look like an adult male. These changes are called male secondary sexual characteristics. Similarly, in girls during puberty the ovaries begin secreting the hormones called estrogen and progesterone. These hormones develop female sexual features. Pituitary gland is small (about 0.5 grams in weight ) pea sized gland, present in brain. It secretes various hormones in blood, which stimulate the target sites ( tests and ovaries) to secrete their hormones.

Reproductive phase of life in humans:

The phase in individuals life during which there is reproduction of gametes is called reproductive phase. In femalse, it is between 13 to 50 years and in males, it is from the age of 13, to life-long. The reproduction of gametes starts earlier in females than in males.The menstrual cycle is controlled by a number of glands and a series of hormonal changes beginnign in the brain.