Life Sciences Glossary: Gonads and Alpha Hydroxyprogesterone

Get top class preparation for competitive exams right from your home: get questions, notes, tests, video lectures and more- for all subjects of your exam.

Gonads

The main function of gonads is to produce gametes, but they also secrete sex hormones. Sex hormones regulate growth and development of accessory sex organs, secondary sexual characters and sexual behaviour. In addition to gonads, adrenal cortex also produce sex hormones. Sex hormones are mostly steroids.

  • Sex Hormones
  • Male Hormones
  • Androgens
  • Testosterone
  • Dilydrotestosterone
  • Female Hormones
  • Estrogens
  • Beta- estradiol
  • Estrange and Estill
  • Progestns
  • Progesterone

Alpha Hydroxyprogesterone

Male Hormones

Male hormones called androgens are produced by interstitial cells of Lending by the stimulation of ICSH from anterior pituitary. The principal male hormones is testosterone. It is responsible for puberty in man. At puberty by the influence of FSH and ICH of pituitary, a large amount of testosterone is produced. Testosterone exerts a feedback inhibitory effect of pituitary LH (ICSH) secretion. Testosterone is secreted by Leyden cells. Surgical removal of testis is castration or orchiectomy. Due to castration the animal becomes agile and strong.

Female Hormones

  • Female hormones are known as estrogens and progestin՚s. Estrogens are produced by the theca sterna cells of Gratian follicles. Estrogens regulate growth and development of female accessory reproductive organs, secondary sexual characters and sexual behavior. Estrogen suppress the production of pituitary FSH. The raptured follicle after ovulation gives rise to corpus lutein which is the source of the secretion of progesterone. Progesterone is the hormone responsible for growth and maintenance of fetus. A temporary endocrine structure after ovulation is corpus letup. Progesterone causes the excessive development of endometrium of uterus. It is responsible for the implantation of embryo in uterus and formation of placenta. The role of progesterone hormone is to thicken uterine wall to increase the blood supply to uterine wall and to build up fat and glycogen in uterine wall. Progesterone also suppresses ovulation and production of pituitary LH. If pregnancy occurs, corpus letup is maintained for about three months. At later stages in pregnancy, the function of corpus lutein will be carried out by placenta through its hormones. It ovaries of a lady are removed in day during menstrual cycle. Menarche is the starting of menstruation.
  • Menstruation is the periodic shedding of the endometrium of the uterus in some mammals (primates) with bleeding. Ovulation occurs usually midway ( during menstrual cycle. Menarche is the starting of menstruation in girls at about 13 - 14 years. Menopause (climacteric) is the period of life when menstruation naturally stops. It usually occurs between the ages of 45 and 50. After menopause the ovaries become smaller, the Gratian follicles disappear and are replaced by fibrous tissues. After menopause, ova, corpora luteal and internal secretions of ovary are no longer formed. The woman cannot become pregnant after the age of 50. After menopause, the secretion of both FSH and LH increases but ovaries do not respond to these hormones.
  • Hormones taken in the form of drugs for contraception are estrogens and progesterone.

Placental Hormones

A temporary structure with endocrine function is placenta. Placenta secretes many hormones like chorionic gonadotropin, placental lactogenic, estrogens, progesterone, relaxing, etc. The presence of HCG (human chorionic gonadotropin) in the urine forms the basis of all pregnancy diagnosis tests. HCG can be detected as early as 14 days after conception.

Reproductive System

Reproduction is one of the most fundamental characteristics of living organisms. Reproduction means the ability to produce individuals of the same species. Primary sex organs produce gametes and also secrete sex hormones. Secondary sex organs are important in reproduction, but do not produce gametes or sex hormones. By accessory sex characters both sexes can be distinguished externally but do not directly play any role in reproduction. The age of sexual maturity is called puberty. External or accessory sex characters first appear in puberty.

Male Reproductive System

Human male reproductive system consists of paired testes, accessory glands, a duct system and penis.

Testes

  • Testes are the primary male sex organs. Testis produces spermatozoa and secretes the male sex hormones testosterone. Testes are located in the extra- abdominal scrotal sacs. Scrotum communicates with abdominal cavity through inguinal canal. The temperature in scrotum is 2 to below the temperature of abdominal cavity. These help in maturation of sperms because maturation of sperm needs low temperature. Cryptorchidism is no descent of testes in scrotum and such persons become sterile. Orchiectomy is the surgical removal of testes. It is also known as castration. Each testis of man contains about 750 convoluted seminiferous tubules which give rise to spermatozoa.
  • Cells of Leydig are found in interstitial connective tissue of testes. They secrete male hormone testosterone. The germinal epithelium lining of the seminiferous tubule is made of two kinds of cells. The most numerous are the small spermatogenic cells or spermatogonia which undergo spermatogenesis to produce sperms. A few larger, tall, columnar supporting cells are called sterol cells or sustencularcels. Sterol cells are located in seminiferous tubules which nourish spermatozoa.
  • Several tubes called vasa efferent arise from rete testis and conduct sperms into epididymis. Epididymis is an irregular, narrow and highly convoluted tubule found on the inner surface of testis. Wolfsan duct of embryo gives rise to epididymis in adult. Sperms achieve maturity and motility in epididymis.

Developed by: