11. Study of Animal Type - Cockroach - part 05 -Excretory System

 

11. Study of Animal Type - Cockroach - part 05 -Excretory System


Excretory System :
  • Malpighian tubules are main excretory organs of cockroach. 
  • They are attached to the alimentary canal between the midgut and hindgut. 
  • They are thin, yellow coloured, ectodermal thread-like structures hanging freely in the haemocoel. 
  • They are about 150 in number.

Malpighian Tubule : 

  • Each Malpighian tubule is lined with a single layer of glandular epithelial cells having microvilli. 
  • Their distal portion is secretory and proximal part is absorptive in function. 
  • They extract water and nitrogenous wastes from the haemocoel and convert them into uric acid and pass them into ileum. 
  • As the cockroach excretes uric acid, it is said to be uricotelic. 
  • In addition, the fat bodies, nephrocytes and uricose glands (in male  cockroach only) also help in excretion.
  • In cockroach, urate cells (nephrocytes) associated with fat bodies and cuticle are also believed to be excretory in function. 
  • The nephrocytes are cells present along with the fat bodies or present along the heart and store nitrogenous wastes. 
  • The excretory products later are removed in the haemocoel. 
  • Some nitrogenous wastes are deposited on the cuticle and eliminated during moulting.

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