Nephritis (diminutive of the ancient Greek. Nephros - “kidney”) - organs of excreta from invertebrates , performing the functions of osmoregulation , extraction and removal from the body of harmful metabolic products . Sometimes they can also be used for removing genital products.
Nephridia are divided into two types: protonephridia and metaneridia . The former are more primitive and are characteristic of flatworms , rotifers , bellyworms , nemertins, and some types of polychaete worms . Protonephridia have the form of branched tubules ( nephridial tubules ), which are closed at the inner ends by the terminal cells ( solenocytes ) and excretory pores ( nephropores ) that open to the outside. Losing solenocytes and communicating with the secondary body cavity, they turn into metanefridia, occurring mainly in annelids . In some ringed worms, nephridia grow together with mesodermal ciliary sex funnels - whole products , forming organs of mixed origin - the so-called nephromyxia . The number of Nephridia in one individual varies from one to several hundred.
Metanefridia
Metanephridia is a type of excretory gland or nephridium in many types of invertebrates , such as annelids, arthropods and mollusks . It usually consists of a ciliary opening of a funnel into a body cavity or body cavity associated with a canal, which can be variously glandularized, folded, or vesiculate, and which usually opens to the external organism. These tubules of the ciliary water pump remove excess ions, metabolism, toxins from food, and useless hormones from the body through the openings - the nephrostomy. This waste is transferred from the body to the pores of Nephridia. Primary urine after filtering the blood (or similar functioning of the fluid) changes to secondary urine through selective reabsorption in the cells lining the metanephridia. In many worms, the nephridic ducts open into the gastrointestinal tract, a condition known as enteronephritis.
Sources
- Nefridiya - an article from the Great Soviet Encyclopedia .
- Nephridia - an article from the Biological Dictionary