TREMATODES Flashcards
Like the cestodes, the trematodes belong to the phylum
Platyhelminthes
For classification purposes, the flukes may be divided into four categories based on the areas of the body that primarily harbor the parasites:
intestinal, liver, lung, and blood.
Commonly known as the [?], these parasites vary in egg, larva, and adult morphology and production processes.
flukes
The trematodes can be divided into two groups, the [?] that infect organs and are foodborne, and the blood flukes or schistosomes that are [?] and infect by direct penetration.
hermaphroditic (self-fertilizing) flukes
dioecious (parasites that reproduce via separate sexes)
Common to all trematodes is their complex life cycle, which almost always include [?] as an intermediate host.
mollusks (snails)
- Morphology: [?] along a long axis and are usually [?], EXCEPT for the blood flukes which are [?]; [?] varies.
Broadly oval/leaf-like, bilaterally symmetrical ;
flattened dorsoventrally
cylindrical; shape and size
- Excretory system: bilaterally symmetrical and open at posterior end with
FLAME CELLS or SOLENOCYTES
• With an [?] extending from the mouth to a short narrow esophagus
oral sucker and a globular pharynx
• [?] is situated at the anterior end of the worm and is equipped with muscular suckers with spines or hooklets.
Oral cavity
Some species possess a large ventral sucker (?) posterior to the oral sucker
ACETABULUM
• bifurcates in front of the ventral sucker into a pair of blind intestinal caeca which may be simple or branched or may reunite to form a single caecum
Esophagus
• Digestion is predominantly an
extra-cellular process
- Nervous system: composed of a group of paired ganglion cells disposed like saddle on the dorsum of
pharynx/esophagus
• All are hermaphrodite/monoecious EXCEPT the
blood flukes
• All are
Oviparous
• Eggs are provided with a lid called [?], EXCEPT the blood flukes
operculum
• The male reproductive system is located at the [?] of the body.
posterior half
It consists of the [?]
prostate gland, seminal vesicle, cirrus, vas deferens, vas efferens, and testes
• The female reproductive system is composed of
uterus, mehli’s gland, ootype, vitellaria, seminal receptacle, and ovary.
Movement is either
through contraction, elongation or flexion
• The trematodes need [?] to complete their life cycle
body of water
• All require 2 intermediate hosts EXCEPT for
blood flukes
• All trematodes lay eggs which upon embryonation, give rise to a ciliated embryo known as [?] → [?] (Dioecious flukes) →[?] (Monoecious flukes)
MIRACIDIUM; CERCARIA; METACERCARIA
- Stages of Trematodes:
a. Egg stage b. Larval stages
