Class Sarcodina

Phylum Protozoa – General Characteristics Unicellular animals Digestion: Intracellular digestion Excretion: By contractile vacuoles (No contractile vacuoles in marine and parasitic protozoa) Respiration: Diffusion Reproduction: * Asexually: Budding, Binary and multiple fission, Sporogony                            * Sexually   : Conjugation, Gamete formation Cyst: Unfavourable conditions - Protozoa covered by cyst (Encystment)           Favourable conditions      - Protozoa comes out of cyst (Exystment)
Class Sarcodina - Locomotory organs: Pseudopodia
1) Entamoeba histolytica		Morphology: 1) Trophozoite stage 2) Pre-Cystic Stage 3) Cystic Stage – Quadrinucleate cyst (during passage through alimentary canal) * Trophozoite has ectoplasm and endoplasm. Endoplasm has RBC.		Lifecycle: Monogenetic  (requires only one host man) Infective cysts are ingested by contaminated food, water (indirect or contaminative transference). Also person to person contact. Cysts (infective stage) swallowed àPass into stomach (resistant to gastric juice) à Intestine (Excystment by tyrosine) à Precystic stage passes into colon (They multiply by binary fission) * Under certain conditions precystic changes into trophozoite which invade the colonic epithelium using their protolytic and cytotoxin enzymes)  à Trophozoite (pathogenic stage) penetrates and enters into hepatic portal vein and enters into the liver and causes hepatic and intrahepatic abscesses. à Under certain conditions trophozoites comes out of the intestinal wall and changes into cysts (quadrinucleate form) which passes out of the host with feces.				Diagnosis: Sigmoidoscopy Stool examination for cysts and precystic forms		Disease: Amoebiasis
2) Entamoeba coli		Morphology: Harmless commensal Endoplasm has only bacteria or other substances but no RBC. Immature cyst – 4 nuclei Mature cyst – 8 nuclei		Life cycle: Same as E. histolytica Remains as lumen commensal without tissue invasion and is non-pathogenic.
3) Entamoeba gingivalis		Morphology: Harmless commensal in the gum of man. Endoplasm has bacteria and other substances but no RBC.		Life Cycle: Transmission: During kissing. No need of cyst. Transference is called direct or contagious.