animal tissue organ and organ system
ANIMAL TISSUE, ORGAN AND ORGAN SYSTEM There is only one cell in the body of the animals of the phylum Protozoa. Animals of the Phylum Porifera are simplest multi-cellular animals. Their cells do not form actual tissue. Though tissues, organs and systems are not formed in members of the phylum Cnidaria (previously known as Coelenterata), their body cells are, however, arranged in two layers. In the animals from phylum Platyhelminthes to Chordata, tissues, organs and organ systems are seen. Members of those phyla are three layered. From there three embryonic cell layers (namely ectoderm, mesoderm and endoderm), tissues, organs and systems are formed. Tissue : In the body of multi-cellular animals some cells remain together and performa particular function. These cells are either formed from the ectoderm, mesoderm or endoderm of the embryo and remain close together. Inter-cellular materials or matrix are present between these cells. These cells may be similar or of different types. Arisin...