- Education and Science»
- Life Sciences
Hormonal Effects On Secondary Sexual Characteristics In Males And Females And The Libido Effect
Increased Libido: Especially In Men
Secondary Sexual Characteristics Development
Hormonal Effects In Males
The development of the genitalia, breasts, body build, voice, facial and pubic hair and other pubertal changes constitute secondary sexual development. The term ‘psychological sex’ and the ‘gender role’ refer to the behavioural and psychological aspects of two sexes. Sexual maturation in males and females occurs in stages and this has been divided into five grades. Changes in male include increase in testicular volume, growth of penis and glans, appearance of scrotal rugosity, and scrotal pigmentation.
Reproduction In Males
The male reproductive system comprises of tests, vas deferens and accessory sex glands. The bulk of the testes is made up of seminiferous tubules embedded in a connective tissue matrix which also contains Leydig cells, blood vessels and lymphatics. Spermatogenesis takes place in the epithelium of the seminiferous tubules and it takes about 74 days. Spermatozoa are stored in the epididymis. Sertoli cells present in the seminiferous epithelium secrete an androgen-binding protein under FSH control. Interstitial tissue of the testes contains the Leydig cells, which secrete the principal testicular hormone-testosterone.
Androgens are steroid hormones which are responsible for conferring male characteristics. They are responsible for the development of male reproductive organs, secondary sexual characters and masculine behaviour. The testicular androgens include testosterone, androgtenedione and dehydroepiandrosterone (DHE). Androgens are secreted by the testes under the influence of the luteinizing hormone (LH) of the pituitary.
The testicular hormones show variation with age. About 4- 7 months after birth, male infants show a substantial increase of circulating testosterone and LH levels. The levels of testosterone fall to low ranges by one year, so also FSH and LH. Puberty occurs by the age of 10-17 years. The FSH reaches adult levels by the age of 15 years and LH reaches adult levels by 17 years. During puberty, gonadotropin output occurs in spurts related to sleep. After completion of puberty, the gonadogropin Levels become steady. After the age of 40 years, marked changes in gonadal function occur in women, but only to a lesser extent in men. Plasma levels of testosterone grafually decline in men. There is a gradual decline in libido and reduction in size of the testes. Testicular function is essentially under a dual gonadotropin control. The LH stimulates the Leydig cells and FSH stimulates seminiferoud tubules.
The ovary increases in size after birth. In the years preceding menarche, the medullary stroma hypertrophize. When puberty develops, cyclic gonadotropin rhythm is established and one follicle develops fully during each cycle and this results in ovulation, with the approach of menopause, the ovary becomes less sensitive to gonadotropin stimulation. Maturation of follicles and ovulation stops. The levels of pituitary gonadotropins increase considerably and remain so for life.
© 2014 Funom Theophilus Makama