Introduction To Trematodes

Introduction to the Helminths Although the Protozoans are an extremely successful group, their organizational plan is limited due to their small size. Limit in size has been escaped through: _____________________________________________ ________________________________________________________________________________________________ The ________________________________ contains some _________________ and includes a number of parasitic organisms. The first group of parasitic animals we will examine are the HELMINTHS – ________________________________

Helminth Phyla Phylum _____________________________ - Phylum _____________________________ - Phylum _____________________________ - (of little economic importance – we will not study them) ______________________________ - study of parasitic worms.

Phylum Platyhelminthes – Chapter 13 The flatworms are the planarians, trematodes, and tapeworms. Forms present in the phylum? ____________________________________________ ____________________________________________ ____________________________________________

Phylum Platyhelminthes – Chapter 13 Characteristics of the Phylum Platyhelminthes: 1. 2. 3. 4.

Characteristics of the Phylum Platyhelminthes cont. 5. first animal group to have this system Function? 6.

Characteristics of the Phylum Platyhelminthes cont. 7. ________________________________________ ________________________________________ - absent in the tapeworms 8. _______________________________________ _______________________________________ - limits size so most flatworms are small and soft-bodied. 9. ________________________________________ - most flatworms are _________________ - both male and female organs occur in an individual

Taxonomy of the Phylum Platyhelminthes We will use the traditional taxonomy: Phylum Platyhelminthes Class Turbellaria – planarians Class Monogenea – monogenetic flukes Class Trematoda – digenetic flukes Class Cestoidea – tapeworms As in the Protozoa, a new taxonomic scheme has been proposed which divides the Turbellaria into several taxa. However, we will not use the new scheme and use the traditional taxonomy.

Class Turbellaria Most turbellarians are free-living scavengers, but some are ___________________________ on other invertebrates. Characteristics of the Turbellaria: _____________________________________________________ - Epidermis is _______________________on the ventral surface to aid in locomotion

Class Turbellaria Anterior end: Digestive tract: One anterior and 2 posterior branches No anus – all wastes have to leave via the mouth

Characteristics of the Turbellaria cont.: ____________________________ ____________________________are present but do not stain in whole mounts ____________________________ larval stages?

Representative Turbellaria Dugesia – freshwater planarian It is a free-living scavenger. Bdelloura – commensal on the __________________________

Class Monogenea All members of the Monogenea are parasitic most are ____________________________________________ a few species occur _____________________________________________________ one species in the hippopotamus eye

Characteristics of the Class Monogenea Characteristic structure is the _______________________ - posterior attachment structure consisting of suckers &/or hooks - function? 2. Anterior feeding and attachment structure is the _______________________ that contains the mouth

Characteristics of the Class Monogenea 3. Digestive tract consists of:

Characteristics of the Class Monogenea 3. Monogeneans are monoecious but cross-fertilize Male reproductive system consists of _______________ ________________________ Female reproductive system consists of: ________________________ – produces oocytes ________________________ scattered throughout the body – produces eggshell protein ________________________– contains 1- few eggs Pathology ____________________________

Characteristics of the Class Monogenea Life cycle is a direct cycle involving one host. Adult on fish gill or in Egg shed into water urinary bladder of frog or turtle hatches attaches to host Free swimming ____________________________ - ciliated - opisthaptor distinct - 2 eyespots - digestive tract & protonephridia present

2 members of Class Monogenea Polystomoidella – parasite in the urinary bladder of the snapping turtle Microcotyle – parasite on the gills of the sheepshead fish. Note numerous clamplike structure on the opisthaptor.

Class Trematoda Trematodes are __________________________________ in all classes of vertebrates. These worms have become structurally adapted for a parasitic existance: 1. possess ___________________for attachment to host 2. have many types of ____________________to produce secretions for ___________________________________ or to produce a ___________________________ 3. have high _________________________(reproductive capacity) to increase chances of completing complex life cycles

Subclasses of the Class Trematoda Of the 3 subclasses in the Class Trematoda, we will examine 2 of them: Subclass Aspidobothrea (= Aspidogastrea) Subclass Digenea

Subclass Aspidobothrea Most are parasites in the viscera of ____________________ A few are parasitic in the intestines of ________________________________________________ Cotylogaster - a parasite in the small intestine of the sheepshead fish- is a representative of this subclass.

Subclass Aspidobothrea - Cotylogaster Characteristic structure is ______________________ composed of numerous shallow depressions called ____________________ (this sucker resembles bottom of tennis shoe)

Subclass Aspidobothrea - Cotylogaster Digestive tract consists of:

Subclass Aspidobothrea - Cotylogaster Adults are monoecious: Male and female reproductive organs are similar to those of digenetic trematodes (I will discuss these shortly) Importance?

Life cycle of Cotylogaster Life Cycle – Addition of fish host: Adult in fish intestine clam eaten by fish Adult in clam viscera egg released into water hatches enters clam via free-swimming _______________________ incurrent siphon - has tufts of cilia - eyespots - long unbranched intestine

Subclass Digenea Most abundant subclass - contains the digenetic trematodes All are _________________________ in all classes of vertebrates inhabit many vertebrate organs (not limited to the intestine) many species infect humans and domestic animals and are of medical and veterinary importance

Subclass Digenea Life cycles are complex involving at least 2 hosts - term "digenea" means 2 beginnings representing the 2 hosts first intermediate host is a ______________________________ definitive host is a ________________________________ many life cycles have a third host between the snail and vertebrate - the second intermediate host - this is an __________________________ ___________________________________________________________ Ma ny larval stages occur in the intermediate host(s) - _____________________________________ occurs in some of the larval stages Adults occur in the definitive host - ___________________________________ occurs in this host

Morphology of an Adult Digenetic Trematode Size - Characteristic structures are the 2 suckers _____________________________ - at anterior end surrounding mouth - for attachment and feeding _____________________________ (= ventral sucker) - located midventral to oral sucker - no internal opening - for attachment to host Suckers are strongly muscularized consisting of bands of smooth muscle Taxonomic importance -

Body wall is a tegument It consists of 2 layers: Syntegument outer ____________________ ____________________ layer - contains mitochondria, secretory bodies, and occasional spines - a chemical layer called the ___________________ lies on top of outer cell membrane syntegument

Tegument Cytotegument - cell bodies or ___________________ beneath the syntegument - each cell contains a nucleus and organelles (RER & Golgi) involved in production of ____________________ - separated from syntegument by layers of tegumental muscle - connected to syntegument by cytoplasmic bridges syntegument cytotegument

Tegument syntegument cytotegument cyton

Tegument Functions of the Tegument: protects trematode from ____________________________ protects trematode from _____________________________ (3) absorbs ______________________________________for trematode nutrition

Trematode Digestive Tract ___________________________ is contained in oral sucker Muscular ___________________ creates sucking action Short esophagus leads into 2 long blind-ending _________________ (= intestinal ceca) No anus so ______________________________________________________

Digestion and the Parenchyma Food taken into the digestive tract consists of ______________________________ ______________________________ Proteins are digested in the lumen of the intestine and _______________________________are absorbed through the intestinal epithelium.

Parenchyma PARENCHYMA - loosely arranged cells filling space between internal organs. Major function is:

Trematode Excretory System EXCRETORY SYSTEM removes excess water that has diffused into worm _______________________________ _______________________________ occur throughout the body cells contain beating flagella that create a hydrostatic pressure which draws water from the parenchyma into the collecting duct flame cells are seen only _______________________________ - at the posterior end of the worm:

Trematode Nervous System Ladder-type system consisting of anterior ganglionic mass, lateral nerve trunks, and connecting commissures. Sense organs of adults are at the cellular level within the tegument - ______________________________________________________________ Sense organs of free-swimming larval stages (miracidium & cercaria) are well developed: ______________________________________________________________

Trematode Reproductive Systems Reproductive systems are extremely elaborate and specialized Digenetic trematodes have ___________________________ - some produce as many as 25,000 eggs per day. Most digenetic trematodes are _________________________ - schistosomes are only dioecious group - monoecious forms commonly cross-fertilize but self-fertilization is possible

Male reproductive system Two testes – function?

Male reproductive system Trematode sperm are unusual for 2 reasons: 1. ________________________________________________________ 2. ________________________________________________________ nucleus 2 flagella mitochondrion

Male reproductive system Shape and position of the 2 testes are important taxonomic characters Shape: Position: Combination of shape/position: branched tandem testes; lobed opposite testes, etc.

Male reproductive system Sperm ducts consist of 2 ____________________________ which join to form a single _______________________ Vas deferens leads into the cirrus sac (= cirrus pouch) that contains: - ____________________________ - sperm-storage area - _____________________________- produces fluids to maintain sperm - _____________________________- male copulatory organ which can be everted through the ______________________________ for copulation

Female reproductive system Single ovary produces ___________________________ which pass along the oviduct to the ___________________________ Taxonomic importance?

Female reproductive system Shape and position of the ovary in relationship to testes important in identification Shape: oval lobed branched

Female reproductive system Ootype is region of female system where: (1) ____________________________ (2) ____________________________

Female reproductive system Structures associated with the ootype: 1. ________________________ - sperm storage area of the female system 2. _________________________ is a short duct which leads from the seminal receptacle to the outside. Laurer's canal was once a vagina but has lost this function and now serves to ________________________________________________

Female reproductive system Vitellaria (= vitelline glands) - occur in _____________________ which generally stain intensely - secrete ______________________ which will coalesce in the ootype to form the _______________________ - vitelline cells containing this protein pass along vitelline ducts which join and lead into the ootype

Female reproductive system Mehlis' gland - surrounds the ootype - produces secretions that ______________________________ ______________________________in the ootype - stains a light pink

Female reproductive system ___________________________ leaves from the ootype and consists of a long, often highly coiled duct containing eggs and sperm As the eggs pass through the uterus, 2 processes occur: 1. 2. Uterus function -

Female reproductive system Anteriorly, the uterus leads into a strongly muscularized duct called the __________________________ - this functions as an ovijector, forcing eggs out the common genital pore - metraterm joins the cirrus sac at the __________________________

Trematode Anatomy – Representives We will examine the anatomy of Prosthogonimus macrorchis, the chicken and duck oviduct fluke, in lab.

Trematode Anatomy – Representatives We will examine the anatomy of Quinqueserialis , the muskrat cecal fluke, in lab.

Trematode Anatomy – Representatives We will also examine the anatomy of the immature adult of Leucochloridiomorpha from a snail. We’ll examine living specimens to see excretory system and beating of the protonephridia. We will compare living specimen to stained whole mount.

Introduction To Trematodes

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Introduction To Trematodes