Reproductive biology includes both sexual and asexual reproduction.
Reproductive biology includes a wide number of fields:
Main article: Human reproduction
Main article: Endocrinology
Human reproductive biology is primarily controlled through hormones, which send signals to the human reproductive structures to influence growth and maturation. These hormones are secreted by endocrine glands, and spread to different tissues in the human body. In humans, the pituitary gland synthesizes hormones used to control the activity of endocrine glands.
Main article: Reproductive system
Internal and external organs are included in the reproductive system. There are two reproductive systems including the male and female, which contain different organs from one another. These systems work together in order to produce offspring.
The female reproductive system includes the structures involved in ovulation, fertilization, development of an embryo, and birth.
These structures include:
Estrogen is one of the sexual reproductive hormones that aid in the sexual reproductive system of the female.
The male reproductive system includes sex accessory glands, sex accessory ducts, testes, and external genitalia.
Testosterone, although present in both males and females, is relatively more abundant in males. Testosterone serves as one of the sexual reproductive hormones in the male reproductive system.
Animal reproduction occurs by two modes of action, including both sexual and asexual reproduction. In asexual reproduction the generation of new organisms does not require the fusion sperm with an egg. However, in sexual reproduction new organisms are formed by the fusion of haploid sperm and eggs resulting in what is known as the zygote. Although animals exhibit both sexual and asexual reproduction the vast majority of animals reproduce by sexual reproduction.