Flatworms Flashcards by Zaide, Caenia Danka

PHYLUM PLATYHELMINTHES (FLATWORMS)

Multicelled animals
Dorsoventrally flattened (leaf-like, ribbon-like, may resemble a masking tape)

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PHYLUM PLATYHELMINTHES (FLATWORMS)

Bilaterally symmetrical with how many body layer?

3 body layers (upper and lower portions)

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Lacking an organ called the Coelom - true body cavity

Acoelomate

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True or False. Phylum Platyhelminthes is Lacking in circulatory and digestive structure.

False. Circulatory and Respiratory Structure.

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Phylum Platyhelminthes has Incomplete digestive tract - how?

have mouth, but no anus

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What are the classes of Phylum Platyhelminthes?

Turbellaria
Trematoda
Cestoda

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Phylum Platyhelminthes
Life cycle: single obligatory host with?

2 consecutive hosts, can be 1 intermediate, 1 definitive host

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Parasitic flatworms (free-living, parasitic)

CESTODA

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Cestoda’s Reproductive system: present both male and female organs

hermaphroditic adult worms (monoecious)

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Cestoda’s Body structure

long, flat, ribbon-like

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Cestoda is composed of?

scolex (head), neck, and strobila (has proglottid segments)

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Organ responsible for the absorption of nutrients and the excretion of waste products

Non-ciliated tegument

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Unarmed scolex
Presence of dorsal and ventral grooves (bothria- attachment organ, used to attach to hosts)
Spatulate scolex - resembles a spoon
Genital pores: midventral
All representatives in man belong to the superfamily Bothriocephaloidea

Pseudophyllidea

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Pseudophyllidea’s Genital pores

midventral

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Pseudophyllidea: All representatives in man belong to the superfamily

Bothriocephaloidea

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Scolex: 4 cuplike suckers and usually a centrally placed apical rostellum; armed with hooks or spines
lacks bothria
quadrate scolex

Cyclophyllidea

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Cyclophyllidea’s genital pores

lateral sides

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Cyclophyllidea: Species found in man belonging to the superfamily

Taeniodea

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• Organ for attachment and orientation of the strobila
• equipped with a hold-fast organ:
suckers, grooves, hooks, spines, glands, tentacles or combination of these

Scolex

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Plural of Scolex

Scolices

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SCOLEX

With well-developed pseudoscolex - false structure of tapeworm

Fimbriaria fasciolaris

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Cup-shaped
Circular/oval outline
With a heavy, muscular wall
Four acetabula on the scolex are retractable (protrusible), hook-bearing rostellum
Holdfast organs

Acetabula/acetabulum

Usually 2-6
Shallow pits or longer grooves
Non-muscular wall

Bothria

Groups of 4
Have highly mobile or motile leaf-like margins
Quite a muscular wall
Projective sharply from the scolex

Bothridia

Unsegmented Between the scolex and the strobila The neck is posterior to the scolex Contains stem cells or germinal cells, giving rise to new proglottids Germinative zone: critical target for antiparasitic drugs

Neck

NECK Germinative zone

critical target for antiparasitic drugs

Unique structure among metazoans Consists of linear sets of reproductive organs of both sexes (testes, ovaries, and uterus) Polyzoic (multiple) proglottids Three divisions of proglottids Immature Mature - male and female organs Ripe/gravid: eggs

STROBILA

• length varies from 3mm to 10 meters, and the number of proglottids ranges from 3 to 4000 segments

Cestodes

Structural organizations of proglottids • craspedote: • Acraspedote: • Apolytic: • Anapolytic:

• craspedote: overlap posteriorly • Acraspedote: do not overlap • Apolytic: proglottids detach when they release eggs, along with gravid proglottids • Anapolytic: remains attached

MORPHOLOGY of Cestodes Mature

testes (minute ovoid testes) Uterus ovary

MORPHOLOGY OF Cestodes Gravid

gravid poglottid with eggs cuticle

Stirred or developed in the uterus

TAPEWORM EGGS

• discharged from the uterus via the uterine pore • ovoid, operculated (has another structure called aberpocular knob - small knob) • immature (unembryonated eggs) when passed in the feces • requires a period of incubation in water before they become mature outside

Pseudophyllidea eggs

• apolytic • spherical, non-operculated, hexacanth eggs or embryos • almost fully embryonated when discharged from the proglottids • Mature or almost mature egg when excreted through feces

Cyclophyllidea eggs

LARVAE OF TAPEWORMS Solid type (non-fluid)

plerocercus/percercoid/procercus plerosercoid/sparganum

LARVAE OF TAPEWORMS Cystic type (fluid-filled, called a cyst)

cysticercoid cysticercus

SOLID TYPE relatively globular Scolex is invaginated into the body of the larva

Plerocercus

SOLID TYPE elongated with head free and invaginate only to the neck

Pleroceroid

CYSTIC TYPE • With a slightly developed bladder anteriorly, into which the head is invaginated • With longated solid posterior portion

Cysticercoid

CYSTIC TYPE • AKA true bladder worm • The head is invaginated into the proximal portion of the bladder

Cysticercus

Cysticercus How many scolex (immature tapeworm head) in bladder.

Single scolex

What type of Cysticercus is this? Only one scolex Taenia spp.

Simple

What type of Cysticercus is this? • Multiple scolices developed from the inner germinal wall

Coenurus

What type of Cysticercus is this? • The germinal layer produces many scolices • Develop into many daughter bladders (brood capsules) • Each of which, in turn, produces many scolices internally

Echinococcus/hydatid

Note: Cyst wall>germinal lining>hyatid sand (granular material)+ ______________

brood capsule>scolices

MEDICALLY IMPORTANT SPECIES OF TAPEWORMS Pseudophillidea

Diphyllobothrium latum

MEDICALLY IMPORTANT SPECIES OF FLATWORM Cyclophyllidea

Taenia solium Taenia saginata Diphylidium caninum Hymenolepis diminuta Railleietina garrisoni Hymenolepis nana Ethinococcus granulosus Ethinococcus multiocularis Spirometra mansoni

MEDICALLY IMPORTANT SPECIES OF FLATWORM Cyclophyllidea

Taenia solium Taenia saginata Diphylidium caninum Hymenolepis diminuta Railleietina garrisoni Hymenolepis nana Ethinococcus granulosus Ethinococcus multiocularis Spirometra mansoni

• Broad or fish tapeworm • Longest human tapeworm • Ivory color • Small colex • Spatulate/almond-shaped scolex • 2 dorsoventral sucking grooves (bothria)

DIPHYLLOBOTHRIUM LATUM

DIPHYLLOBOTHRIUM LATUM Mature proglottids: Male organs: Female organs:

Mature proglottids: broader than long Male organs: numerous testes, single genital pore Female organs: symmetrically bilobed ovary; vagina extending from a common genital pore in the midventral line (allows self-fertilization)

DIPHYLLOBOTHRIUM LATUM A single worm may discharge as many as?

1 million eggs daily

DIPHYLLOBOTHRIUM LATUM DIAGNOSTIC CHARACTERISTICS

rosette-shaped or highly coiled uterus in the middle of the gravid segment

DIPHYLLOBOTHRIUM LATUM EGGS Give at least 3 characteristics

broadly ovoid light golden yellow conspicuous operculum moderatlet thick shelles knob on the shell at the bottom of egg contain an immature embryo when discharged in the feces

dog or double-pored tape worm (2 vaginal openings), cucumper tapeworm Very common intestinal tapeworm of dogs and cats 10-70 cm length 60-175 proglottids

DIPYLIDIUM CANINUM