绦概带曼cestodes

Morphology of tapeworms: The scolex
The scolex is the part of the worm that anchors it to the intestinal epithelium and prevents that the worm is passed with the digested food.
The male system consists of numerous testes, vasa efferentia from each testis to the sperm duct. The cirrus is surrounded by the cirrus pouch. Most often the cirrus pouch and female vagina enter a common chamber, the genital atrium, and share a common opening, the genital pore.
larvae are • cysticercoid, • cysticercus • and hydatid • (some of these larvae
provided amplification • （Coenurus=many scolices)
Differentiation of the two orders (tapeworms)
Cyclophylidea
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Diferentiating Pseudophylidea
Cyclophylidea
Feature
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The reproductive system
• The female includes a vagina from the genital pore to a seminal receptacle; an ovary; a single oviduct, the ootype, the duct from the seminal receptacle.
The proglottids on the right are immature; note that the reproductive organs are just beginning to differentiate.
Mature proglotids
Mature proglottids of Taenia sp.
Scolex
two grooves
four suckers
(bothrium)
Pseudophyllidea Cyclophyllidea
Uterus
Developmental stages (metacestodes)
(D. latum)
(D. latum)
(Hymenolepis sp.)
(T. solium)
(E. granulosus)
• Pseudophyllidean cestodes
• procercoid: in the 1st • Intermediate host.(at an
Pseudophyllidea
Cyclophyllidea
Scolex
& holdfast 2 sucking grooves
4 suckers
Uterus curved ducts
with opening
Vitelline
gland

follicle-like, anterior
to ovary
Intermediate
segments behind the neck) Immature segments Mature segments Gravid segments
Scolex/neck/ immature proglotid
Anterior region of showing the scolex and neck region.
Different types of scolices Some cestodes carry a rostellum which is armed with hooks. Muscular holdfast organs include suckers or acetabula (usually 4 per scolex), weakly muscled grooves (bothria, 2 per scolex).
4 Hermaphroditic.
5 The nutrition of tapeworms is through integument (skin) as they lack digestive tract.
Tegument
Cestodes
• They have suckers or sucking grooves and teeth that grasp the host (Holdfast organs)
Morphology of adult tapeworm
Adult consists of segments (proglottids)
1 Scolex (head) 2 Neck (the region of
segment proliferation) 3 Strobila ( A chain of
Characteristics:
1 Adult lives in the intestine of vertebrates.
2 One or two intermediate hosts.
3 Humans may serve as final host or intermediate host (Transport host or Paratenic host)
Strobila
• 1 Tiny scolex • 2 Strobila which
makes up most of the “worm” • 3 The strobila consists of a linear series of proglottids • 4 Each mature proglottid carries a set of female and male reproductive organs
• The uterus leads from the ootype and may have either an opening or uteropore or end blindly. Proglottids without uteropores detach when gravid.
• The egg is formed in the ootype with the contributions from the ovary and the vitellaria.
Scolex of Taenia Solium
Strobilation
• Strobilation: asexual
process of forming segments • New proglottids are
continuously formed in the neck just below the scolex (A) • Along the length of the worm the proglottids increase in size and maturity, developing • from premature (B) • to mature (C) • to the “gravid” stage (D) • in which essentially the entire proglottid is filled with the uterus and eggs.
Diagram of oncosphere of Hymenolepis diminuta, dorsal view
Taeniid eggs. The eggs of Taenia saginata and T. solium are indistinguishable morphologically. The eggs are rounded, 31 to 43 µm, with a thick radially striated brown shell. Inside each shell is an embryonated oncosphere with 6 hooks. CDC
• The embryonate egg contains the oncosphere a larva that will penetrate the intestinal wall after eggs are swallowed by intermediate host
• The oncospheres of eucestoda have three pairs of hooks which makes it easy to identify them
each proglottid measures about 4 mm in length
Mature proglottid genital organs
Gravid proglottid: only the uterus exists in the segment
Differences between Pseudophylidea and
Classification of cestodes
Phylum Platyhelminthes (flatworm) Class Cestoda Two important orders: Order Pseudophyllidea : Spirometra mansoni Diphyllobothrium latum( fish tapeworm) Order Cyclophyllidea : Teania solium (pork tapeworm) Teania saginata (beef tapeworm) Echinococcus granulosus (hydatid worm)
Developmental stages
• With very few exceptions vertebrates are the final host harboring the adult tape worms
• Many invertebrates and vertebrates are parasitized as intermediate hosts
end there is a cercomere=tail with 6 hooklets) • plerocercoid :The larvae look fairly similar to the adult In the second host
• Cyclophyllidean • The medically important
• Behind a short neck are repeated parts of the worm, each containing reproductive structures with eggs and sperm.
/ perit/biology_image_gallery1 .htm
host
2
Egg
elliptic, thin shell,
an operculum, an egg
cell and many yolk cells
sack-like, without opening
masses, posterior to ovary
1 spherical, thick embryophore, an oncosphere