 New students, in this topic we shall discuss the reproductive hormones in detail. The reproductive hormones of vertebrates belong to two chemical categories, steroid sex hormones and peptide hormones. These hormones develop the primary and secondary sexual characters. They also control and regulate reproductive activities of animals. First, we shall discuss in detail the steroid sex hormones which include progesterone, astrogens and androgyns. Progesterone and astrogens predominate in female animals while androgyns predominate in male individuals. The steroid sex hormones are produced by the gonads that is testes and ovaries. Small quantities of these hormones are also produced by the adrenal cortex of both sexes in varying quantities. Dear students, the steroid sex hormones are synthesized from cholesterol. Cholesterol is the parent molecule with which all steroid hormones are produced. Cholesterol is first converted to progesterone. Progesterone is then transformed into androgyns like a ketastro-steroid or andro-steenidion in both sexes in various aspects of growth and morphology. Progesterone is then converted to androgyns like a ketastro-steroid or a ketastro-steroid or a ketastro-steroid. That is, astrogens, androgyns and progesterone are very important in both sexes in various aspects of growth and morphological differentiation. They are also important in the regulation of reproductive cycles. And they are also important in the development of sexual behaviors. Dear students, now we shall discuss the roles of androgyns in males. Androgyns trigger the development of primary male sexual characters in the embryo. For example, testes, penis, development of vas deferens, development of epididymus and prostate gland and development of seminal vesicles. All these characters are called the primary male sexual characters and they are formed because of the action of androgyns in the embryo. Dear students, androgyns also produce male secondary sexual characters. These characters develop after the puberty. These characters include the loins' mane, roosters' comb, plumage in birds, facial hair in men, body musculature in males, and voice coarseness. These are secondary sexual characters and they develop after puberty. Dear students, androgyns primarily stimulate spermatogenesis by the germinal cells of testes. They also contribute to the synthesis of specialized proteins which are called myofibrillar proteins in the muscles of males. They are produced under the effect of androgyns. Dear students, now we shall discuss the role of steroid sex hormones in females. Hormones and progesterones are the primary steroid sex hormones in females. They stimulate the development of female primary sexual characters, for example uterus, ovaries and vagina. These hormones also develop the secondary female sexual characters, for example the development of breasts. These hormones also regulate the reproductive cycles, that is the menstrual cycle in human and some other primate females and astro cycle in all other mammalian females. Dear students, in addition to steroid sex hormones, two peptide hormones also play an important role during parturation and lactation. These hormones are prolectin and oxytocin. Prolectin stimulates the development of and growth of mammary glands and milk synthesis in mammals. Prolectin plays a special role during parturation, when it produces strong contractions in the uterus wall in which there is childbirth. In addition to this, after the oxytocin birth, the mother's mammary glands also plays a role in the ejection of milk.