Nematode Excretory System: Structure & Significance

1. By: Sundus Suhail
M.Sc.
Nematology
15ZYM19

2. Introduction
• Excretory system is one of the most simplest system of
nematodes.
• Waste is turned into ammonia and is excreted through the body.
• The major nitrogenous waste product is ammonia.
• The excretory products of nematodes are numerous like amino
acid , peptides, uric acid , fatty acid
• The excretory pore is located in the anterior mid ventral line
close to the nerve ring.
• Parasitic worms tend to have a glandular process to excrete.
• Nonparasitic worms tend to have a much more tubular method
of releasing their salty waste.

3. Components of Excretory System
Four different cell types :
 A pair of gland cell
 One canal cell (Excretory cell)
 One duct cell
 One pore cell

5. 1.Gland cell:
• A shaped
• Formed by the fusion of two identical cells
• Secrete materials from large membrane bound vesicles
• Secretion is a hormone which helps in molting

6. 2.Canal cell:
•Uninucleate
•H shaped
•Forms a bridge between left and right excretory canal
•Form numerous gap junctions with the epidermis and are in direct contact
with the pseudocoleomic fluid

7. 3.Duct cell:
•Loop shaped
•It connects with excretory cell on one side and pore cell on other side
•It surrounds duct from its origin to the boundary of pore cell
4.Pore cell:
•Specialized transitional epithelial cell
•Does not have any sphincter, so it remains open throughout
•Opens to the exterior via excretory pore.
•Laser ablation of duct cell and pore cell leads to absence
• of cuticle

8. Types of Excretory System
Excretory system is varied and in some groups it is completely absent as in
Dorylamoidea , whereas Longidorous macrosoma belonging to this group
has well developed excretory system.
The division of excretory system is as follows:
1.Glandular Type :
•Present in class Adenophorea
2.Tubular Type
•Present in class Secernentea

9. 1.Glandular Type
• Primitive and basic type.
• Consists of a simple single ventral gland cell without
collecting tubules..
• This gland is connected to the excretory pore by a
duct that terminates in a pouch like structure known
as ampulla.
• Example: Chromadora
• In Enoplia , Phanodermopsis the single cell is lobed
• In Plectus, the duct is very elongated.
Chromadora
Phanodermopsis
Plectus

10. 2.Canalicular or
Tubular Type
•Consists of four
cuticularised canals.
•Two are anterior and
another two are posterior
canals.
• These are joined by a
transverse duct.
• A terminal duct arises
and opens on ventral side
via the excretory pore.
•Example Tylenchids ,
Rhabditids

11. Modifications of the Excretory System
1. H shaped/ Oxyuroid Type:
 Four excretory canals are present.
 The anterior canals are slightly shorter than the
posterior ones.
 Canals extend throughout the length of the body.
 Excretory sinus is present.
 No excretory gland cells are present.
 Example: Oxyurids
Oxyuroid Type
Anterior
excretory canal
Posterior
excretory canal

12. 2. Rhabditoid Type:
 Four cuticularised canals are present.
 Excretory gland cell is present.
 It is filled with secretory granules.
 Excretory duct connected with sinus.
 Excretory pore is present.
 Example : Rhabditis

13. 3. Ascaroid Type
 All four excretory canals are present .
 Left anterior canal is shorter then posterior one.
 Excretory cell is present.
 Excretory duct is present.
 Example: Ascaris

14. 4. Cephaloboid Type:
 Also called as inverted U shaped type.
 No excretory gland cell is present.
 Two excretory canals with only one extending anteriorly.
 A terminal cuticularised duct connected with sinus and opens to
exterior via excretory pore.
 Example: Cephalobus

15. 5. Anisakid Type:
•Asymmetrical type.
•Anterior canals absent.
•Gland cell is absent.
•Only posterior canal is present.
•Excretory cell is present.
•Example : Anisakis
Excretory cell
Excretory
canal

16. 6. Tylenchid Type:
 A single tube runs throughout the body length.
 It is found in either of the lateral hypodermal chords.
 Excretory sinus connected with canal.
 No gland cell.
 Excretory duct which opens via excretory pore
 Example : Tylenchids

17. Alternate Cellular Means of Excretion
There are certain cells in the nematode body which help in excretion:
 Hypodermal glands: They enhances the efficiency of excretion by
functioning throughout the length of the body.
 Prerectum: It is the connection between intestine and rectum.
 Coelomocytes : These are the cells situated in the body cavity.

18. Significance of Excretory System
 Maintaining osmoregulation.
 Regulating turgor pressure in the body cavity.
 Removes foreign particle.
 In the infective L3of Haemonchus contortus,
the excretory system may be involved in ex sheathment .
 In female of citrus nematode Tylenchulus semipenetrans,
excretory pore is located posteriorly and it is
responsible for the secretion of the gelatinous
matrix surrounding the eggs.
Citrus nematode

19.  Ecdysis is accompanied by the synthesis of the enzyme leucine
aminopeptidase in the excretory gland and its release via the excretory duct
into the space between the two cuticles in Phocanema.
 Excretory secretory are used as models for pharmaceutical discovery
Example: E/S product released by filarial worms are capable of influencing
flow in mammalian blood and lymph vessels thereby helping in
hypertension and cardio vascular diseases.
• E/S products are used as markers for infection
Example: Og4C3. a circulating antigen ,that is easily detected in patients
suffering from the infection of Wuchereria bancrofti