CHAP29_2402 - Chapter 29 1 BIOLOGY 2402 Anatomy and...

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Unformatted text preview: Chapter 29 1 BIOLOGY 2402 Anatomy and Physiology Lecture Chapter 29 DEVELOPMENT AND INHERITANCE Chapter 29 2 DEVELOPMENT AND INHERITANCE Developmental Anatomy is the study of the sequence of events from the fertilization of a secondary oocyte to the formation of an adult organism. PRENATAL DEVELOPMENT Prenatal Period – Is the period from conception until birth, and it is divided into three parts: 1. Germinal Period – Approximately the first 2 weeks of development during which the primitive germ layers are formed. 2. Embryonic Period – From about the second to the end of the eighth week of development, during which the major organ systems come into existence. 3. Fetal Period – The last 30 weeks of the prenatal period, during which the organ systems grow and become more mature. Last menstrual Period (LMP) of the mother is used by the medical community to calculate the clinical age of the unborn child. Postovulatory Age is used to describe the timing of developmental events. Fertilization Fertilization- Is a process by which a sperm cell attaches to a secondary oocyte, the sperm head enters the oocyte cytoplasm, and joins the oocyte pronucleus to form a new nucleus. Chapter 29 3 During fertilization the genetic material from a sperm cell (spermatozoon) and secoondary oocyte merges into a single nucleus. Of the 300-500 million sperm introduced into the vagina, less than 1% reach the secondary oocyte. (Fertilization normally occurs in the uterine (fallopian) tube when the oocyte is about one-third of the way down the tube, usually (about 12-24 hrs.) Transportation of Oocyte through the Uterine (Fallopian) Tube: 1) Peristaltic contractions; 2) Action of cilia Transportation of Sperm or Mechanism by which they reach Uterine tube: 1) Swim up the female tract by means of whip like movements of their flagella. 2) Acrosin an enzyme produced by the Acrosome of the sperm stimulates sperm motility and migration. 3) Probably transported by muscular contraction of the uterus stimulated by prostoglandius in semen. 4) Oocyte is though to secrete a chemical that attracts sperm (negatively charged, positively charged) *(Although sperm undergo maturation in the epididymis, they ar still not able to fertilize an oocyte until they have remained in the female reproductive tract for about 10 hours .) * Capacitation is the functional changes that sperm undergo in the female reproductive tract that allow them to fertilize a secondary oocyte. Three destructive Enzymes secreted by the Acrosomes of the sperm : (1) hyaluronidase (2) acrosin (3) neuraminidase (During capacitation, the membrane around the acrosome becomes Chapter 29 4 fragile so that several destructive enzymes- hyaluronidase , acrosin , and neuraminidase- are secreted by the Acrosomes.) These enzymes help sperm penetrate the Corona Radiate and Zona Pellucida ....
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This note was uploaded on 03/10/2012 for the course BIOL 2403 taught by Professor Campbell during the Spring '12 term at Texas Pan American.

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CHAP29_2402 - Chapter 29 1 BIOLOGY 2402 Anatomy and...

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