General organisatoon of monogenea for M.Sc students

1. GENERAL ORGANISATION
OF MONOGENEA

2. INTRODUCTION
Phylum - Platyhelminthes
Trematoda CestodaTurbellaria
ORDER
Monogenea
Ex-
Polystoma
Aspidobotheria
Ex-
Aspidogaster
Digenea
Ex- Fasciola
CLASS

3. GENERAL Characters Of Trematoda
A
• Ecto-or Endoparasitic form.
• Body shape – Leaf like.
B
• Body wall without epidermis and cilia.
• Well developed suckers are present.
C
• Mostly Hermaphrodite except few families of Digenea.
• Life cycle simple or complicated.

5. morphology
Body sucker
Nervous
system
Reproductive
system
Alimentary
tract

6. Body sucker
Presence of a posteriorly situated adhesive structure-
Opisthaptor
Large, Circular, Muscular disc generally is separated
completely or partially, into smaller suckers by septa.
The opisthaptor does bear 2-4 large hooks known as
Anchors.
A single anchor is divided into root, base and shaft.
Many species possess various numbers
of small suckers divided by septa, ranging
from 6-240 depending on the species.

7. In addition to the opisthaptor ,monogeneids usually
possess 2 anteriorly located auxiliary sucker-the prohaptor.
Prohaptor situated one on each side of the mouth.
Prohaptor may appear as pits, sucker, or discs.

10. Reference: Thomas Chang
Polystoma Diplectamum

11. Alimentary Tract
Mouth- anterior, flanked on each side by a prohaptor.
In Discocotyle sagittata, prohaptors modified as
buccal suckers.
Mouth is surrounded by an oral sucker.
Head glands and head organ are present.
Intestinal tract is an inverted Y shape.
In Dactylogyrus amphibothrium, the caeca are not
united posteriorly , but possess side branches.
In Polystoma, the caeca extend into the disc shaped
opisthaptor.

12. Anatomy of monogenids

13. Nervous system
It consist of large cluster of nerve ganglia and cells.
Two nerves masses connected- transverse commissure
Situated at the anterior end of the body .
In some species the “brain” is arranged in a well formed
circumesophageal ring.
1.
2.
3.

14.  Nerve fibres extend
from this ring.
 Ventral nerves are highly
developed and are
connected by a series of
transverse commissures
.
 Branches of nerve fibres
innervate to the various
sucker muscles and
other portions of body.
 In monogenea, 1 or 2
pairs of eye spots are
present.
Source: Thomas Chang

15. Osmoregulatory system
• It is of the protonephritic type.
• Flame cells are present at the end of collecting
tubules
• Each tube makes a “U” curve.
• The end of ascending tube there is a swelling
known as the contractile bladder
• The tubes leaves the bladder empty to the
outside through the two separate nephridiopore
• Nephridiopores are situated dorsolateral to the
mouth.

16. Osmoregulatory system

17. Reproductive system
THE MALE SYSTEM-
i) It consist of 1,2 or 3 testis, ex- Leptocotyle
and Monocotyle.
ii) A single Vas efferens arises from each testis.
iii) A common atrium is found, the aperture is
known as genital pore.

18. The Female system
 A single ovary is present.
Shape may range globular to elongate.
Oviduct arises from the surface of the ovary.
Unicellular glands, collectively known as the
Mehlis’ gland secrete into the ootype.
Terminal of the uterus opens into genital atrium.

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