Introduction of Tapeworms Flashcards by Danica Mae Araza

Cestodes is also known as?

Tapeworms

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Two orders of cestodes (tapeworms)

✓ Order Cotyloda / Pseudophyllidea (Pseudotapeworms)
✓ Oder Eucestoda / Cyclophyllidea (True tapeworms)

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Order Cotyloda/Pseudophyllidea also known as?

Pseudotapeworms

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Oder Eucestoda/Cyclophyllidea also known as?

True tapeworms

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SN of Pseudotapeworms

Cotyloda/Pseudophyllidea

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SN of True tapeworms

Eucestoda/Cyclophyllidea

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Organ attachment of Order Eucestoda/Cyclophyllidea (True tapeworms)

Suckers and rostellum

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Stage of infective to 1st IH of Order Eucestoda/Cyclophyllidea (True tapeworms)

Hexacanth embryo

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No. of IH of Order Eucestoda/Cyclophyllidea (True tapeworms)

One

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Egg shedding of Order Eucestoda/Cyclophyllidea (True tapeworms)

Via thysanus

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Organ of attachment of Order Cotyloda/Pseudophyllidea (Pseudotapeworms)

Bothria

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Stage infective to 1st IH of Order Eucestoda/Cyclophyllidea (True tapeworms)

Coracidium

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Tapeworms also known as?

Segmented worms

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No. of IH of Order Eucestoda/Cyclophyllidea (True tapeworms)

Two

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Egg shedding of Order Eucestoda/Cyclophyllidea (True tapeworms)

Via uterine pore

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Differentiate Order Cotyloda/Pseudophyllidea (Pseudotapeworms) and Eucestoda/Cyclophyllidea (True tapeworms)

The organ of attachment of order Cyclophyllidea are suckers and rostellum, stage infective to first IH is the hexacanth embryo with only one IH and eggs are shedded via thysanus. On the other hand, Order Pseudophyllidea organ of attachment is the bothria, stage infective to first IH is the coracidium with two IH and eggs are shedded via uterine pore.

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General characteristics of Tapeworms

With elongate flat body
Without body cavity
Without alimentary canal
Hemaphroditic
Body consist of head or scolex, neck and strobila
The scolex may bear hooks or suckers which may be armed; rostellum may be present
Strobila is segmented
Each proglottid consists of 1 or 2 sets of male and female reproductive organ
Has an indirect life cycle
The size varies from a few mm to several meters in length

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A protrusible part

rostellum

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Typical Cestode Parts

scolex
rostellum
sucker
neck
strobila
Immature proglottid
Mature proglottid
Gravid proglottid
proglottid

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Scolex or head of a tapeworm are composed of what?

rostellum
sucker
neck

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Strobila of tapeworms are composed of what?

Immature proglottid
Mature proglottid
Gravid proglottid
Proglottid

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Mobile retractable structure of a tapeworm

Rostellum

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Segments of the Tapeworm

Strobila

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Part of strobila where eggs are shedded, uterus and ova are located, and can be detached to be a new tapeworm

Gravid proglottid

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The body of the tapeworm is covered by this which serves as a protective structure

tegument

The chief organ for nourishment being composed of interspersed microtriches (microvilli) which aids in absorption of food

tegument

Aids in the absorption of food

microtriches (microvilli)

Excretory organs of tapeworm are composed of what?

Rostellar Nerve Ring and 2 Lateral Nerve Cords

both of these types of reproduction may occur

cross-and self-fertilization

A metameric repetition of reproductive organs

Proglottidization

Male Reproductive Organs

one or more testes vas efferens vas deferens Cirrus (surrounded by cirrus sac) Genital sinus

True tapeworms Cirrus

Single lateral

Pseudotapeworms

Central genital

Female Reproductive Organs

Bilobed ovary Ootype Vitelline gland (compact in cyclophyllideans and follicular in pseudophyllideans; much reduced than flukes) Oviduct which receive the receptaculum seminis Vagina Uterus arises from the ootype Uterus opens distally via a uterine pore or blindly Common genital pore usually opens on the lateral side

Ootype of a female reproductive organ is surrounded by?

Mehli's glands

Vitelline gland of Cyclophyllideans

Compact

Vitelline gland of Pseudophyllideans

Follicular

Structures that develop once the uterus disappears by degeneration

Paruterine organs

It assumes the function of the uterus e.g. hyaline egg capsules and dense areas of fibromuscular tissue

Paruterine organs

Eggs of the tapeworms are shed from the ____ and passed out with the faeces.

Strobila

Disintegrated eggs may fall into single eggs, give an example

Taenia sp.

Isolated pieces of uterus (paruterine organs) containing egg packets (give examples) or capsules (cocoons) each with 8-30 eggs (give example).

Mesocestoides, Davainea, Avitellina spp. Dipylidium sp.

Egg shedding of Cyclophyllidea

Eggs are fertilized → reproductive and other internal organs degenerate → proglottids are detached (singly or in chains) → disintegration of gravid proglottids eggs are set free via the thysanus (apolysis)

disintegration of gravid proglottids eggs are set free via what?

thysanus (apolysis)

Egg shedding of Pseudophyllidea

Fertilized eggs are continuously discharged through the uterine pore → egg production ceases → exhausted proglottids are detached from the strobila (pseudoapolysis)

Cestode Eggs general characteristics

1. May be embryonated or non-embryonated. 2. A fully embryonated egg contains an oncosphere

It is a hexacanth embryo with 3 hook pairs found at the center of a fully developed cestode egg

oncosphere

It is the stage infective to the 1st intermediate host

oncosphere or hexacanth embryo

It has 6 hooksb(3 pairs) or lines inside

Hexacanth enbryo

4 embryonic envelops of typical oncosphere

egg capsule/shell outer membrane embryophore oncospheral membrane

Egg hatchings of tapeworms depends on what?

Environmental stimulus - light in Diphyllobothrium latum Mechanical action -Anocephala Digestive enzymes of host - Taenia Combination of mechanical and action of digestive enzymes

Example of Environmental stimulus

light

Species that are hatched due to Environmental stimuli like light

Diphyllobothrium latum

Species that are hatched due to Mechanical action

Anocephala

Species that are hatched due to Digestive enzymes of host

Taenia

Types of Egg Formation

1. Egg capsule 2. Egg pouches

Eggs are covered or protected with material derived from the uterus

Egg capsule

Eggs are covered with materials derived from the parenchyma

Egg pouches

Egg pouches eggs are derived from the?

parenchyma

Egg capsules are derived from the?

uterus

the infective larval form of tapeworms

Metacestode

Types of Metacestodes

1. Procercoid 2. Plerocercoid 3. Tetrathyridium 4. Cysticercoid 5. Cysticercus 6. Strobilocercus 7. Coenurus 8. Hydatid

first metacestode stage of Pseudophyliids

Procercoid

solid-bodied with hooks on the cercomer in the posterior region

Procercoid

follows a procercoid; occurs in the second intermediate host of of Pseudophyllids, elongate, solid-bodied and bears an adult scolex

Plerocercoid

found only in Mesocesotoidea

Tetrathyridium

worm-like, solid larva with deeply invaginated scolex

Tetrathyridium

single evaginated scolex embedded in a small solid cyst, found in small intermediate host such as arthropods

Cysticercoid

Most common type of metacestodes

Cysticercoid

single scolex invaginated into itself in a large, fluid- containing vesicle or bladder

Cysticercus

single scolex evaginated and it attached to the cyst by a chain of asexual proglottids (resembling a juvenile strobila) which are digested away after ingestion by the final host leaving only the scolex

Strobilocercus

large, fluid-containing bladder lined with a germinal epithelium producing a number of invaginated scolices by budding which remains attached to the wall

Coenurus

large, fluid-containing cyst with a laminated cuticular wall lined with a parenchymal inner layer producing many invaginated protoscolices which lies free or in bunches (brood capsules)

Hydatid

many scolex but free

Hydatid

Cotyloda (Pseudophyllidea) general characteristics

* Vary from few mm to 10 meters or more in length * With 2 deep grooves instead of suckers called bothria (dorsal and ventral) * Hooks are absent * Each segment has usually one set of reproductive organs * With numerous testes * With scattered vitellaria * Bilobed ovary * "uterine pore" is present * eggs are operculated and unembryonated when laid

deep grooves instead of suckers

bothria

CN of metacestodes

Bladder Worms

Plerocercoid also known as?

Sparganum

Species with procercoid as its infective stage

Diphyllobothrium latum

Species with tetrathyridium as its infective stage

Mesocestoides lineatus

Species with cysticercoid as its infective stage

Dipylidium caninum

Species with cysticercus as its infective Stage

Taena saginata "beef tapeworm"

Species with strobilocercus as its infective stage

Taenia taeniaeformis

Species with coenurus as its infective stage

Taena multiceps Taenia serialis

It causes true gid as it is found in the brain of sheep

Coenurus

Common types of metacestodes

Strobilocercus Coenurus

CN of Hydatid

Echinococcus cyt / Hydatid cyst