Types of Animal Tissues

January 26, 2016 January 26, 2016

In all the animals, tissues develop from the embryonic germ layers during the blastula (early stage of embryonic development) phase. On the basis of germ layers, all animals except Porifera and Protozoa; there are either two or three germ layers.

The animals which develop from two germ layers (ectoderm and endoderm) are called Only Ctenophores (comb jellies) and Cnidarians (Hydra, Corals, Sea Anemones, Jelly Fishes, Sea Pens) have this feature.
The animals which develop from three germ layers viz. ectoderm, mesoderm and endoderm are called triploblastic. All animals from Platyhelminthes to Humans are triploblastic.

Types of Animal Tissues

There are 4 categories of animal tissues viz. Epithelial Tissue, Connective Tissue, Muscular Tissue and Nervous Tissue.

Epithelial Tissue

Epithelial tissue makes the covering of the internal organs as well as our body. This is the simplest and non specialized tissue. Epithelial tissue originates from all the three embryonic layers viz. Ectoderm, Mesoderm and Ectoderm.

Connective Tissue

The tissues that bind several tissues in the body are called connective tissues. They do the function of supporting the organs and packaging of the organs. Please note that except muscles all the connective tissue is derived from the mesoderm of the embryonic blastula. 30% of the body by mass is composed of connective tissue. This tissue includes connective tissue proper, skeletal issue and fluid tissue.

Collective tissue proper includes the below two types:
- Collagen fibres which make tendons that connect muscles to bones. We note here that Vitamin C helps in synthesis of Collagen and lack of vitamin C causes a deficiency of connective tissue called “Scurvy”.
- Yellow elastic fibres which make ligaments that connect bones to bones. Yellow elastic fibres are also present in arteries to provide elasticity to them. We note here that Yellow Elastic Fibre is resistant to chemical change, though it loses elasticity with aging. Resistance to chemical change is also evident from the fact that when mummies are dissected, arteries are among the internal organs that might be found in most intact condition!
Skeletal Tissue is derived from the mesoderm of embryonic blastula {this question is frequently asked in UPSC and state exams}. There are two types of skeletal tissues viz. cartilage and bone.
- Cartilage is softer, elastic tissue that makes joints between bones, rib cage, ear, nose, bronchial tubes, intervertebral discs etc.
- Bone is a highly mineralized tissue in which connective tissue part is 1/3rd while mineral part is 2/3rd portion.
Fluid Connective Tissue includes Blood, Lymph and Cerebrospinal fluid(CSF). Blood and Lymph circulate in the body and help in transportation of the metabolites. They have a common matrix called plasma. They have various kinds of cells which are called “corpuscles. There are no fibers or matrix in fluid connective tissue.

Nervous Tissue

Nervous Tissue is the main component of brain; spinal cord and peripheral nerves. It helps in the regulation and control of body functions and activities and allows us to see and perceive the world. It is made of neurons {nerve cells}, and Neuroglia, which helps in propagation of the nerve.