L26: Blood Flukes Flashcards
What does the digestive tract of Trematodes consist of
fore gut and two cacea
Go in depth about whats in the foregut of treamtodes
- anterior mouth, pharynx, esophagus
- ingestion and assimilation
*The mouth surrounded by a muscular oral sucker for attachment and feeding
Go in depth about whats in the two caeca of treamtodes
- longitudinal blind tubes
✓ intestine-like
✓ variable length depending on trematode species
✓ Digestion and absorption of food occur in the caeca
What is the tegument in Trematodes
syncytium – a multinucleated tissue with no cell boundaries
What is the synticum made of
- outer zone – the distal cytoplasm which is bound by the
plasma membrane - An inner zone – the proximal cytoplasm
What is inner/outer zone of syncytium. What are they composed of
proximal cytoplasm / distal cytoplasm
Distal
* glycocalyx is a surface coat covering the entire plasma
membrane
* Surface invaginations function much like microvilli
* The glycocalyx and surface invaginations same
function as in cestodes
* Tegumental spines embedded in the distal cytoplasm and
project outward from the surface
Proximal
*It is connected to the distal cytoplasm by cytoplasmic bridges
* Contains nuclei, endoplasmic reticulum, Golgi complexes and
mitochondria
* involved in repair and maintenance of components of the
distal cytoplasm
Whare the zones of the muscular system. Other key muscle
subtegumental:
underlying tegumes of longi, circular and diagnotl layers
gastodermal
line cacare to help move food down
ventral scucker: contractile muscle fibres located mid verntrally for attachment, no opening here
What are general characteristrics of somoregulatory system
consits of protenephridia, a tubular system without opening made of flame cells
flame cells has flagella, remove excess water by creating hydrostatic pressure
flame cell open to terminal tubule tat converge from larger tubes leading to excretory bladder
duct of bladder opens to exterior of organism located posterioly
How can trematodes reproduce
✓ Self-fertilization in hermaphroditic worms
✓ Cross-fertilization in hermaphroditic worms
✓ Mating between 2 dioecious worms – this occurs ONLY in Schistosoma spp
Describe the male reproductive system
- Generally, includes 2 testes, 2 vas efferens, a common vas deferens, a cirrus, cirrus sac, seminal vesicle and the prostate gland
- Depending on the species, one or more of these components may be missing, in different size, or in a different position
- Schistosomes are multi-testicular
Describe the female reproductive system
Consists of a single ovary that forms ova
* Depending on the species, the ovary may be anterior/ posterior to, or between the testes
- Other components are the oviduct which comprises the ootype (where fertilization occurs), Mehli’s gland and vitelline glands
(both function to secrete the eggshell), uterus (a long, convoluted tube) and Laurer’s canal (in some species)
Draw the reproductive sytem
Male reproductive system of a digenetic trematode
Female reproductive system of a digenetic trematode
Describe trematode eggs
Eggs are ovoid, shelled and contain the embryo and other materials
- The typical eggshell is equipped at one end with a lid-like
structure, the operculum
✓ The operculum allows the larva to hatch - In species lacking an operculum (mainly schistosomes), the
eggshells rupture longitudinally when larva (miracidium) hatch - Hatching occurs only under precise conditions of temperature,
osmolarity and light - Specific size and structural characteristics of trematode eggs are
useful in diagnosis
What time of parasite are trematodes
obligate parasite
In general describe trematode life cycle
✓ 1st intermediate host is an invertebrate, almost always a mollusk (harbors larval stages)
✓ 2nd intermediate host includes fish/ arthropod/ another mollusk (harbors the encysted juvenile trematode)
✓ Definitive host is a vertebrate (harbors the adult trematodes)
