◼ 1678年，荷兰显微镜 专家Anton van Leeuwenhoek发现了精 子，Nicolas Hartsoeker （ the other codiscoverer of sperm） 描绘了一幅精子中存 在一个预成的小人 (a preformed human — "homunculus")的画面
◼ 1678年，荷兰显微镜 专家Anton van Leeuwenhoek发现了精 子，Nicolas Hartsoeker （ the other codiscoverer of sperm） 描绘了一幅精子中存 在一个预成的小人 (a preformed human — "homunculus")的画面
◼ 17世纪末，意大 利的博物学家 Lazzaro Spallanzani 发现 过滤去除精子之 后的精液不能使 蟾蜍的卵子受精 （filtered toad semen devoid of sperm would not fertilize eggs）
◼ 17世纪末，意大 利的博物学家 Lazzaro Spallanzani 发现 过滤去除精子之 后的精液不能使 蟾蜍的卵子受精 （filtered toad semen devoid of sperm would not fertilize eggs）
◼ In 1824, J. L. Prevost and J. B. Dumas （French speaking）发现只有性成熟的雄 性动物才能产生精子，而未成熟的和年老 的动物体内都没有精子产生，同时他们还 注意到骡的不育性。 ◼ They claimed that sperm were not parasites, but rather the active agents of fertilization. They proposed that the sperm entered the egg and contributed materially to the next generation
◼ In 1824, J. L. Prevost and J. B. Dumas （French speaking）发现只有性成熟的雄 性动物才能产生精子，而未成熟的和年老 的动物体内都没有精子产生，同时他们还 注意到骡的不育性。 ◼ They claimed that sperm were not parasites, but rather the active agents of fertilization. They proposed that the sperm entered the egg and contributed materially to the next generation
◼ Until the 1840s, A. von Kolliker described the formation of sperm from cells within the adult testes. It was only in 1876 that Oscar Hertwig and Herman Fol independently demonstrated sperm entry into the egg and the union of the two cells' nuclei. ◼ Fertilization was at last recognized as the union of sperm and egg, and the union of sea urchin gametes remains one of the best-studied examples of fertilization
◼ Until the 1840s, A. von Kolliker described the formation of sperm from cells within the adult testes. It was only in 1876 that Oscar Hertwig and Herman Fol independently demonstrated sperm entry into the egg and the union of the two cells' nuclei. ◼ Fertilization was at last recognized as the union of sperm and egg, and the union of sea urchin gametes remains one of the best-studied examples of fertilization
2. 精子的结构 人类精子由头部、中部（颈部）和尾部组成
2. 精子的结构 人类精子由头部、中部（颈部）和尾部组成