Labeled sperm cell

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NCBI Bookshelf. Molecular Biology of the Cell. New York: Garland Science; In most species, there are just two types of gamete , and they are radically different. The egg is among the largest cells in an organism, while the sperm spermatozoon , plural spermatozoa is often the smallest.

The male reproductive system can be thought of as a series of tubes. These tubes deliver the male gametes from their site of production in the testes to their destination outside the body. The system itself is divided into two distinct units: testes, located outside the major body cavity and housed in the scrotum and the excretory duct system, which transports the sperm from the testes and whose accessory glands produce and modify the contents of semen.

Actomyosin interactions are reportedly the principal mechanism for the transport of nonmotile sperm cells of flowering plants inside the pollen tube and inside the embryo sac. Myosin has been demonstrated on the generative cell the predecessor of sperm cells , although it is unclear from previous studies whether myosin is located directly on the plasma membrane of the male germ cells or on the external plasma membrane of the pollen cell that surrounds them. Immunogold scanning electron microscopy was used to localize myosin on isolated tobacco sperm cells, with and without associated membranes. When present, the pollen tube plasma membrane surrounding the sperm cells was labeled by an antimyosin antibody, as were pollen tube cytoplasmic organelles.