Ex_5_Fertilization2009

Ex_5_Fertilization2009 - Exercise 5. Fertilization and...

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Exercise 5. Fertilization and development 73 EXERCISE 5 ECHINODERM DEVELOPMENT * FERTILIZATION AND EARLY DEVELOPMENT IN ECHINODERMS Equipment and supplies needed Fertilization dissection microscopes compound microscopes slides and coverslips echinoderms beakers for eggs and sperm sea water syringe Pasteur pipettes KCl (0.5M) Development Waterbath and shaker prepared slides of starfish embryos Microliter pipette 20, 200, and 1,000 μl pipetmen pipette tips The purpose of this exercise is to demonstrate fertilization and early development in echinoderms, a model system for animal development, and to prepare and examine giant chromosomes of the fruit fly, Drosophila. PART I: Echinoderm Development One of the fundamental questions of biology is how the egg and sperm unite to form a single cell, the fertilized egg, which then divides and develops into a complex multicellular organism. This process involves cell recognition and fusion, then growth and an elaborate pattern of specialization. The initial event in development is fertilization - the fusion of egg and sperm to form a zygote. Considerable research has been directed toward understanding this process and echinoderms, such as sea stars, sea urchins or sand dollars, have been used extensively in this research. These animals have several advantages for studies on fertilization. 1) they produce large numbers of eggs and sperm 2) the release of these gametes is easily induced 3) the fertilized eggs can be cultured in a simple solution (sea water) 4) embryonic development is rapid.
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Exercise 5. Fertilization and development 74 In order to understand fertilization, it is necessary to know the structure and function of the various components of the egg and sperm. Sperm The sperm consists of a head (containing a nucleus, very little cytoplasm, and a dense acrosome at the tip) , a midpiece (containing the mitochondria which supply energy for tail movement) and the tail , which propels the sperm through the liquid medium. SPERM
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Ex_5_Fertilization2009 - Exercise 5. Fertilization and...

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