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| Description: The embryonic period extends from fertilization through the eighth week of development. Fertilization—merging of genetic information from sperm and secondary oocyte. Sperm swim from the vagina to the cervix using their tails. Sperm pass through the uterus and uterine tubes mainly due to contraction of the walls of these structures. To fertilize an egg, sperm must penetrate the corona radiata (granulosa cells) and the zona pellucida (glycoprotein layer outside of the oocyte’s plasma membrane). The enzymes of the sperm’s acrosome, along with tail movement, allow the sperm to penetrate the corona radiata. Glycoprotein ZP3 in the zona pellucida is a receptor for the sperm. Membrane proteins in the sperm head bind to ZP3 and acrosomal enzymes are released to digest a path in the zona pellucida. Picture Stats: Views: 2106 Filesize: 1.25MB Height: 900 Width: 1094 Source: https://biology-forums.com/index.php?action=gallery;sa=view;id=40472 |