Animal Tissues of Class 11

  • A tissue is a group of cells that are similar in structure, origin and function.
  • The word “tissue” was given by French anatomist and physiologist Bichat (1771-1802)
  • Study of tissues is called histology (Gr. histos-tissue, logos-study).
  • Term ‘histology’ was given by German histologist Mayer (1819).
  • Italian scientist Marcello Malpighi (1628-1694) is known as “founder of histology”
  • Histology is also called microscopic anatomy (=microanatomy).
  • Bichat (1771-1802) is considered “Father of histology”.
  • Histogenesis (histos-tissue, genesis-formation). Formation and development of tissues from undifferentiated or embryonic cells; also called histogeny.
  • The phenomenon of differentiation of cell groups into tissues is known as histodifferentiation.
  • Histolysis (GK. histos-tissue, lysis-to break) Degeneration of tissues.

Interaction with Mankind

Rat is known as an important pest of crops and stored grains. Nearly 20 per cent of these are damaged every year by the rats.

Rat destroys fields by making burrows and tunnels. The burrows made by rats often provide shelter to snakes including the poisonous ones.

Rat makes burrows in the houses and causes damage to the household including books, clothes, food, vegetables, etc. Rat is a carrier of flea, which spreads plague.

Rat is an important component of food chain as several reptiles, birds and mammals prey on it.

In some countries rat is used as a food item. Rats have been used in teaching and biomedical research for more than a century. The researchers in the field of genetics produced several phenotypic strains by colour and coat variations. The albino rat that is commonly used for teaching and researches in institutions is a product of laboratory breeding. These are also used as an experimental animal to test drugs that are to be finally used by the human beings.

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