Meiosis, Germ Cells, and Fertilization
Meiosis, Germ Cells, and Fertilization
Meiosis, Germ Cells, and Fertilization
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Sperm Are Highly Adapted for Delivering<br />
Their DNA to an Egg<br />
• Head<br />
– highly condensed haploid nucleus<br />
– DNA in the nucleus is extremely tightly packed<br />
– chromosomes of many sperm lack the histones, but with protamines<br />
– Acrosomal vesicle - specialized secretory vesicle<br />
• Midpiece<br />
• Tail<br />
– Mitochondria - ATP is generated<br />
– strong flagellum propels the sperm<br />
– central axoneme emanates from a basal body<br />
– With two central singlet microtubules surrounded by nine evenly<br />
spaced microtubule doublets.<br />
– sliding of adjacent microtubule doublets past one another, driven by<br />
dynein motor proteins<br />
• Acrosome reaction<br />
– a sperm contacts the egg coat, the contents of the vesicle are<br />
released by exocytosis
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