The Reproductive System by Alvin Silverstein

These are of varying degrees of detriment to the body. The reproductive system is susceptible to a number of diseases and disorders.

The ovum fuses with the sperm cell and fertilization completes while embryonic development begins.

Once fertilization is initiated, the secondary oocyte completes meiosis II and becomes an ovum. The haploid secondary oocyte will only complete the second meiotic stage if it encounters a sperm cell. After meiosis I is complete, the egg cell is called a secondary oocyte. The polar bodies degrade and are not fertilized. This asymmetrical cytokinesis results in one large egg cell (oocyte) and smaller cells called polar bodies. In meiosis I of oogenesis, daughter cells divide asymmetrically. Oogenesis (ovum development) occurs in the female ovaries. Hundreds of millions of sperm must be released in order for fertilization to take place. This process occurs continuously and takes place within the male testes. Spermatids then transform into mature spermatozoa through spermiogenesis. The production of sperm cells is known as spermatogenesis. Stem cells develop into mature sperm cells by first dividing mitotically to produce identical copies of themselves and then meiotically to create unique daughter cells called spermatids. When sex cells unite during fertilization, the two haploid sex cells become one diploid cell that contains all 46 chromosomes. Human sex cells contain one complete set of 23 chromosomes. Meiosis produces gametes that are considered haploid because they have half the number of chromosomes as the parent cell. Through a sequence of steps, replicated DNA in a parent cell is distributed among four daughter cells. Gametes are produced by a two-part cell division process called meiosis.

The reproductive system is closely associated with other organ systems, particularly the endocrine system and urinary system.

The growth and activity of these parts are regulated by hormones. The reproductive system is usually comprised of either male or female reproductive organs and structures. When a male and female sex cell unite, an offspring grows and develops. The primary function of the human reproductive system is to produce sex cells. In sexual reproduction, two individuals produce offspring that have some of the genetic characteristics of both parents. The human reproductive system and the ability to reproduce make life possible.

The Reproductive System by Alvin Silverstein