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Morphology of Entamoeba histolytica

Morphology of Entamoeba histolytica

Entamoeba histolytica is a small, microscopic parasitic amoeba. In its life cycle, it occurs in three distinct forms:

        1. Trophozoite or Magna
        2. Precystic or Minuta
        3. Cysts

I. Trophozoite or Magna

  • Also known as trophic or magna form.
  • Most active, motile and feeding form.
  • This stage is pathogenic to man.
  • It lives in the mucous and sub-mucous layers of the large intestine of man.
  • The outermost body covering or plasmalemma is a thin, elastic and semi-permeable membrane.
  • The cytoplasm is differentiated into ectoplasm and endoplasm.
  • Irregular, constantly changing due to pseudopodia.
  • Food vacuoles are present.

a) Nucleus

    • Endoplasm contains a nucleus.
    • In the centre of nucleus, there is an endosome or karyosome which resembles a small dot-like.
    • The fluid-filled space between the nuclear membrane and endosome is marked by spoke-like striations of chromatin material.

b) Pseudopodium

    • When moving, E. histolytica produces anteriorly a large, broad and blunt pseudopodium.
    • The parasite is monopodial.
    • The trophozoite moves with this single pseudopodium.

II. Precystic or Minuta

  • This stage of Entamoeba histolytica is small, spherical, non-motile and non-feeding form.
  • The food vacuoles are absent.
  • It lives in the lumen of the large intestine.
  • It is non-pathogenic to man.
  • It can change into magna form and invade the tissues of intestine.

III. Cysts

  • Under normal condition, minuta forms undergo encystation.
  • It becomes rounded and surrounded by a thin, highly resistant and refractile cyst wall.
  • A mature cyst is a spherical body.
  • Its cytoplasm is clear and contains one or two glycogen masses.

Read More:

Structure and Diagram of Amoeba