Monocystis - Life Cycle, Classification and Structure

Monocystis,Monocystis Life Cycle, Monocystis Classification, Monocystis Causes

Monocystis - Life Cycle, Classification and Structure

Monocystis - Life Cycle, Classification and Structure

Under this post, Monocystis - Life Cycle, Classification and Structure, we will read through the following topics :

  • Monocytis Classification
  • Monocytis Structure
  • Monocystis Life Cycle

Monocystis Classification

Systematic position and Scientific Classification :

Phylum –  Protozoa

Subphylum – Sporozoa

Class – Telospora

Subclass – Gregarina

Order – Eugregarinida

Genus – Monocystis

MONOCYSTIS – The Earthworm Parasite

HABIT AND HABITATE - Monocystis is an endoparasite in the seminal vesicle and coelom of earthworms.

MONOCYSTIS STRUCTURE -  The feeding stage is called trophozoite that develops within the sperm morula, which is a group of developing sperms in the seminal vesicles of earthworm. There is only one host, the earthworm.

SHAPE AND SIZE - Young trophozoites are rounded and oval, about 5 micron long but full grown trophozoites are elongated, spindle-shaped, about 500 micron long and 40 micron broad.

PELLICLE -  Body of trophozoites is covered with pellicle that contains longitudinal contractile fibres called myonemes, which help in metabolic locomotion.

CYTOPLASM -  Endoplasm contains paraglycogen globules and volutin granules. Single nucleus which is placed anteriorly in the upper half of body. It contains haploid chromosome.

NUCLEUS - Nucleus is single and vesicular with spherical form. It contain only one nucleolous. Nuclear membrane bear pores.


Monocystis is categorised as a monogenetic parasite which means its life cycle is completed in a single host that is earthworm.

The life cycle is completed in 6 steps :

  • Gamantogamy
  • Sporogamy
  • Transference
  • Sporozoites
  • Invention of seminal vesicle
  • Development of trophozoites

1. Gamantogamy - The motile infective stage is a sporozoite which is haploid and enters the sperm morula of earthworm to feed and grow.  This stage is called trophozoite, which eventually differentiates into agamont or gamete producing cell or gametocyte. The process is called gamontogamy.

It involve following steps :

A. Syzygy - Two gametocytes or gamonts become rounded and make a non-sexual association which is called Syzygy. The two gamonts then become enclosed in a common envelope called the gametocyst or gamontocyst. This process is called encystation.

B. Gametogony - The gametocytes then undergo multiple fission called gametogony to produce large number of gametes. The gametes are anisogametes. The male gamete are small or pointed and female gamete are large and rounded.

C. Syngamy - The cell membrane between two parent gametocytes break and the gametes of the two cells mix together and fuse in pairs. This fusion of gametes is called syngamy, which forms zygote or sporont.

2. Sporogony – Spherical zygote transform into oval body. The diploid zygote secretes around it a tough covering called the sporocyst and the resultant structure is now called spore.

3. Transferance – Exact mode of transmission from one host to another is not known. These sporocysts are released into soil mainly after the death of earthworms or when earthworm is eaten by birds and sporocysts are excreted through the faecal matter of birds. The sporocysts are also transferred from one host to another during copulation.

  • During copulation - The spore are transfered from one host to another during copulation along with spermatozoa and seminal fluid.
  • Death of host - When a hostworm dies and decay the spore get scatterd in soil. When infected soil is eaten by fresh worm these also enter its alimentary canal.
  • By predatory birds - When an infected worm is engulfed by predatory birds the spores pass out and swallowed by another warm .it enter into another body.
  • Automization - When the posterior region of earthworm automised the spore are liberated in soil. The infected soil is eaten by a fresh worm . the spore are injested by it.

4. Sporozoites - The sporozoites are minute spindle shaped uninucleate protoplasmic bodies. Each contain mitochondria, golgi bodies and reserve food granules. At the enterior region a pair of secretory orgenells are present. The secretion help in penetration through tissue. Enterior end also bears conoids and micromere.

5. Invasion of seminal vesicle - The sporozoites secretes a specific substance which help them in the penetration through the tissue. Sporozoites make their entry into the epithelial cell of alimentary canal mucosa. Generally one sporozoites penetrates on cell. From the mucosal cell, sporozoites are transferred into seminal vesicle, the sporozoites enter into group of sperm forming cells (sperm morula). Here sporozoites feed and grow into young trophozoites.

Although all earthworms are infected with monocystis, their fertility is not greatly impaired by the action of parasite.  The trophozoites mainly grow inside sperm morulae, inhibiting the event of spermatogonia and spermatids but this does not affect the amount or quantity of sperms produced.

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