Human Fertilisation and Development

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  • Topic: Gamete, Spermatozoon, Sperm
  • Pages : 3 (1117 words )
  • Download(s) : 267
  • Published : March 27, 2013
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Human Fertilisation and Development
Each day cute little babies are born into this world and being dazzled by their beauty we forget all about the long complicating process that took place which made it possible to have a baby. Therefore in my essay I am going to discuss the human reproductive cell, fertilisation and the development of a human life. Humans reproduce sexually, with both parents contributing half of the genetic makeup of their offspring via sex cells or gametes. Gametes produced by the male parent through Spermatogenesis process are called spermatozoa (commonly called sperm cells) and gametes produced by females through Oogenesis process are called oocytes (commonly referred to as ova or eggs). As gametes are formed, the 46 chromosomes from each parent cell (23 pairs of chromosomes) are divided through meiosis so that each gamete is haploid, having only 23 unpaired chromosomes. Spermatozoa, produced by males, contain a 23rd chromosome that is either an X chromosome (female) or the analogous Y chromosome (male), making each sperm cell either female or male. Spermatozoa have a head that contains a nucleus, a mid piece that contains mitochondria, and a tail with its end piece. Sperm cells produced in the testes move to the epididymis, a coiled tube at the base of the penis where they are stored and matured. During ejaculation, or the ejection of sperm from the penis during orgasm, sperm travel from the epididymis through a long tube called the vas deferens to the urethra. This single tube, which extends from the bladder to the tip of the penis, is also the means by which urine passes out of the body. Liquid secretions from various glands combine with sperm to form the semen, or seminal fluid. Ejaculated semen may contain as many as 400 million sperm. Oocytes are also haploid, and since they are formed only by females, the 23rd chromosome can only be an X chromosome. Each oocyte is protected by several layers of granulosa cells called the corona...
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