Introduction To Trematodes


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Introduction To Trematodes

  1. 1. Introduction to the Helminths <ul><li>Although the Protozoans are an extremely successful group, their organizational plan is limited due to their small size. </li></ul><ul><li>Limit in size has been escaped through: </li></ul><ul><ul><ul><li>_____________________________________________ </li></ul></ul></ul><ul><ul><ul><li>________________________________________________________________________________________________ </li></ul></ul></ul><ul><li>The ________________________________ contains some _________________ and includes a number of parasitic organisms. </li></ul><ul><li>The first group of parasitic animals we will examine are the HELMINTHS – ________________________________  </li></ul>
  2. 2. Helminth Phyla Phylum _____________________________ - Phylum _____________________________ - Phylum _____________________________ - (of little economic importance – we will not study them) ______________________________ - study of parasitic worms.
  3. 3. Phylum Platyhelminthes – Chapter 13 The flatworms are the planarians, trematodes, and tapeworms. Forms present in the phylum? ____________________________________________ ____________________________________________ ____________________________________________
  4. 4. Phylum Platyhelminthes – Chapter 13 Characteristics of the Phylum Platyhelminthes: 1. 2. 3. 4.
  5. 5. Characteristics of the Phylum Platyhelminthes cont. <ul><li>5. </li></ul><ul><li>first animal group to have this system </li></ul><ul><li>Function? </li></ul><ul><li>6. </li></ul>
  6. 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
  7. 7. 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.
  8. 8. Class Turbellaria <ul><li>Most turbellarians are free-living scavengers, but some are ___________________________ on other invertebrates. </li></ul><ul><li>Characteristics of the Turbellaria: </li></ul><ul><li>_____________________________________________________ </li></ul><ul><li>- Epidermis is _______________________on the ventral surface to aid in locomotion </li></ul>
  9. 9. Class Turbellaria <ul><li>Anterior end: </li></ul><ul><li>Digestive tract: </li></ul><ul><li>One anterior and 2 posterior branches </li></ul><ul><li>No anus – all wastes have to leave via the mouth </li></ul>
  10. 10. Characteristics of the Turbellaria cont.: <ul><li>____________________________ ____________________________are present but do not stain in whole mounts </li></ul><ul><li>____________________________ </li></ul><ul><li>larval stages? </li></ul>
  11. 11. Representative Turbellaria Dugesia – freshwater planarian It is a free-living scavenger. Bdelloura – commensal on the __________________________
  12. 12. Class Monogenea <ul><li>All members of the Monogenea are parasitic </li></ul><ul><li>most are ____________________________________________ </li></ul><ul><li>a few species occur _____________________________________________________ </li></ul><ul><li>one species in the hippopotamus eye </li></ul>
  13. 13. Characteristics of the Class Monogenea <ul><li>Characteristic structure is the _______________________ </li></ul><ul><li>- posterior attachment structure consisting of suckers &/or hooks </li></ul><ul><li>- function? </li></ul><ul><li>2. Anterior feeding and attachment structure is the _______________________ that contains the mouth </li></ul>
  14. 14. Characteristics of the Class Monogenea 3. Digestive tract consists of:
  15. 15. Characteristics of the Class Monogenea <ul><li>3. Monogeneans are monoecious but cross-fertilize </li></ul><ul><li>Male reproductive system consists of _______________ ________________________ </li></ul><ul><li>  Female reproductive system consists of: </li></ul><ul><li>________________________ – produces oocytes </li></ul><ul><li>________________________ scattered throughout the body – produces eggshell protein </li></ul><ul><li>________________________– contains 1- few eggs </li></ul><ul><li>Pathology </li></ul><ul><li>____________________________ </li></ul>
  16. 16. Characteristics of the Class Monogenea <ul><li>Life cycle is a direct cycle involving one host. </li></ul><ul><li>  </li></ul><ul><li>Adult on fish gill or in Egg shed into water urinary bladder of frog or turtle </li></ul><ul><li>  hatches </li></ul><ul><li>  attaches to host </li></ul><ul><li>Free swimming ____________________________ </li></ul>- ciliated - opisthaptor distinct - 2 eyespots - digestive tract & protonephridia present
  17. 17. 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.
  18. 18. 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    
  19. 19. Subclasses of the Class Trematoda Of the 3 subclasses in the Class Trematoda, we will examine 2 of them: Subclass Aspidobothrea (= Aspidogastrea) Subclass Digenea  
  20. 20. 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.  
  21. 21. Subclass Aspidobothrea - Cotylogaster Characteristic structure is ______________________ composed of numerous shallow depressions called ____________________ (this sucker resembles bottom of tennis shoe)  
  22. 22. Subclass Aspidobothrea - Cotylogaster Digestive tract consists of:
  23. 23. Subclass Aspidobothrea - Cotylogaster Adults are monoecious: Male and female reproductive organs are similar to those of digenetic trematodes (I will discuss these shortly) Importance?
  24. 24. 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  
  25. 25. Subclass Digenea <ul><li>Most abundant subclass - contains the digenetic trematodes </li></ul><ul><li>All are _________________________ in all classes of vertebrates </li></ul><ul><ul><li>inhabit many vertebrate organs (not limited to the intestine) </li></ul></ul><ul><ul><li>many species infect humans and domestic animals and are of medical and veterinary importance </li></ul></ul>
  26. 26. Subclass Digenea <ul><li>Life cycles are complex involving at least 2 hosts - term &quot;digenea&quot; means 2 beginnings representing the 2 hosts </li></ul><ul><ul><li>first intermediate host is a ______________________________ </li></ul></ul><ul><ul><li>definitive host is a ________________________________ </li></ul></ul><ul><li>  </li></ul><ul><ul><li>many life cycles have a third host between the snail and vertebrate - the second intermediate host - this is an __________________________ ___________________________________________________________ </li></ul></ul><ul><li>Ma ny larval stages occur in the intermediate host(s) - _____________________________________ occurs in some of the larval stages </li></ul><ul><li>  </li></ul><ul><li>Adults occur in the definitive host - ___________________________________ occurs in this host </li></ul>
  27. 27. Morphology of an Adult Digenetic Trematode <ul><li>Size - </li></ul><ul><li>Characteristic structures are the 2 suckers </li></ul><ul><li>_____________________________ - at anterior end surrounding mouth - for attachment and feeding </li></ul><ul><li>_____________________________ (= ventral sucker) - located midventral to oral sucker - no internal opening - for attachment to host </li></ul><ul><li>Suckers are strongly muscularized consisting of bands of smooth muscle </li></ul><ul><li>Taxonomic importance - </li></ul>
  28. 28. Body wall is a tegument <ul><li>It consists of 2 layers: </li></ul><ul><li>Syntegument </li></ul><ul><li>outer ____________________ ____________________ layer </li></ul><ul><li>- contains mitochondria, secretory bodies, and occasional spines </li></ul><ul><li>- a chemical layer called the ___________________ lies on top of outer cell membrane </li></ul>syntegument
  29. 29. Tegument <ul><li>Cytotegument </li></ul><ul><li>- cell bodies or ___________________ beneath the syntegument </li></ul><ul><li>- each cell contains a nucleus and organelles (RER & Golgi) </li></ul><ul><li>involved in production of ____________________ </li></ul><ul><li>- separated from syntegument by layers of tegumental muscle </li></ul><ul><li>- connected to syntegument by cytoplasmic bridges </li></ul>syntegument cytotegument
  30. 30. Tegument syntegument cytotegument cyton
  31. 31. Tegument <ul><li>Functions of the Tegument: </li></ul><ul><li>protects trematode from ____________________________ </li></ul><ul><li>protects trematode from _____________________________ </li></ul><ul><li>(3) absorbs ______________________________________for trematode nutrition </li></ul>
  32. 32. 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 ______________________________________________________
  33. 33. 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.  
  34. 34. Parenchyma PARENCHYMA - loosely arranged cells filling space between internal organs. Major function is:
  35. 35. Trematode Excretory System <ul><li>EXCRETORY SYSTEM removes excess water that has diffused into worm </li></ul><ul><li>_______________________________ _______________________________ occur throughout the body </li></ul><ul><li>cells contain beating flagella that create a hydrostatic pressure which draws water from the parenchyma into the collecting duct </li></ul><ul><li>flame cells are seen only _______________________________ </li></ul><ul><li>- at the posterior end of the worm: </li></ul><ul><li>  </li></ul><ul><li>  </li></ul><ul><li>  </li></ul>
  36. 36. 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: ______________________________________________________________      
  37. 37. 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  
  38. 38. Male reproductive system Two testes – function?    
  39. 39. Male reproductive system Trematode sperm are unusual for 2 reasons: 1. ________________________________________________________ 2. ________________________________________________________     nucleus 2 flagella mitochondrion
  40. 40. 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.
  41. 41. 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
  42. 42. Female reproductive system Single ovary produces ___________________________ which pass along the oviduct to the ___________________________ Taxonomic importance?
  43. 43. Female reproductive system Shape and position of the ovary in relationship to testes important in identification     Shape: oval lobed branched    
  44. 44. Female reproductive system Ootype is region of female system where: (1) ____________________________ (2) ____________________________
  45. 45. Female reproductive system <ul><li>Structures associated with the ootype: </li></ul><ul><li>1. ________________________ - sperm storage area of the female system </li></ul><ul><li>2. _________________________ is a short duct which leads from the seminal receptacle to the outside. </li></ul><ul><ul><li>Laurer's canal was once a vagina but has lost this function and now serves to ________________________________________________ </li></ul></ul>
  46. 46. 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  
  47. 47. Female reproductive system Mehlis' gland - surrounds the ootype   - produces secretions that ______________________________ ______________________________in the ootype - stains a light pink    
  48. 48. 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 -
  49. 49. 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 __________________________
  50. 50. Trematode Anatomy – Representives We will examine the anatomy of Prosthogonimus macrorchis, the chicken and duck oviduct fluke, in lab.
  51. 51. Trematode Anatomy – Representatives We will examine the anatomy of Quinqueserialis , the muskrat cecal fluke, in lab.
  52. 52. 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.