Asexual reproduction in animals occurs through fission, budding, fragmentation, and parthenogenesis. Sexual reproduction starts with the combination of a sperm and an egg in a process called fertilization. This can occur either outside the bodies or inside the female. The method of fertilization varies among animals. Animal cells lack the rigid cell walls that characterize plant cells. The bodies of most animals (all except sponges) are made up of cells organized into tissues, each tissue specialized to some degree to perform specific functions. In most, tissues are organized into even more specialized organs. Most animals are capable of complex and relatively rapid movement compared to plants and other organisms. Most reproduce sexually, by means of differentiated eggs and sperm.
For more details: http://sciaeon.org/veterinary-sciences-and-medicine/home
Submit your manuscript: http://sciaeon.org/submit-paper
Contact us: veterinary@sciaeonopenaccess.com