Myxozoa: These microscopic aquatic parasites infect fish and other aquatic animals. Their spores contain a polar capsule with a coiled polar filament. When triggered, the filament rapidly unravels, anchoring the spore to the host's tissues and aiding in invasion. Their filament structure is even used for species identification. 2. Microsporidia: These single-celled parasites infect a wide range of hosts, including humans and insects. Their spores also possess a polar tube (similar to a filament) for injecting infectious contents into host cells. The firing mechanism of the polar tube is incredibly fast, ensuring efficient parasite entry. These parasites are considered emerging pathogens due to their increasing prevalence and impact on human health. These are just two examples, and many other parasite groups utilize similar structures for host invasion. Research on these mechanisms continues to elucidate their complexity and role in parasite survival and host interaction.

1. PARASITE WITH POLAR
FILAMENTS:
NAME: Mahnoor Baig

2. PARASITES:
DEFINITION:
Parasites are those organism which live inside or outside the host
body for nutrition & abode i.e. Ectoparasites and Endoparasites.
 Some parasites are beneficial while some parasites are harmful.
i.e. some are edible and role in pollination of crops and used in
medicines etc.
Some are harmful as they act as pest and some are vectors of diseases.

3. PARASITES WITH POLAR FILAMENTS:
 Not all the parasites are having polar filaments. The polar
filaments are found in Myxosporean organisms.
POLAR FILAMENTS:
 It is a special type of structure found in Head capsule of
Myxosporean organisms.
 It is a coiled structure present In polar capsule along its
inner wall.
 If present outside the body of host they are sticky and help
in attachment of spores with the intestinal wall of Host and
also help in separation of these spores from host body.

4. Importance of Polar Filaments:
 It is important in species classification.
 In some species like Ceratomyxa; it form a straight basal section and
rest of filament remain coiled.
 In SPHAEROMYXA; the filament is Zig zag structure. So, on basis of
morphological differences of polar filament species are classified.
 It is a characteristic feature of microsporidia found in the spore used
to infiltrate host cells. These eukaryotic parasites infect mainly fish.

5. MYXOSPOREAN PARASITES:
 These are minute microscopic, spore forming intracellular parasites
that invade vertebrates & invertebrates. Belong to Myxozoa clade and
belong to phylum Cnidaria.
 They have complex life cycle which comprises vegetative forms in 2
hosts;
o Vertebrate host (Fish)
o Invertebrate host (Annelids)
 In each host, they releases different types of spores.
1. Myxospores
2. Actinospores
 Spores are usually oval shaped but can be rod-shaped or spherical.
These spores are highly resistant that can survive outside the host for
up to several years.

6. myxospore Actinospore

7. LIFE CYCLE OF MYXOZOA:

8. LIFE CYCLE OF MYXOZOA:
 Myxospores are ingested by annelids, in which the
polar filaments extrude to anchor the spore to the gut
epithelium 0f host by acting as a kind of “needle”.
 Opening of the shell valves allows the sporoplasms
to penetrate into the gut epithelium, travel to tissues
elsewhere in the body via the blood stream.
 Subsequently, the parasite undergoes reproduction
and development in the gut tissue, and finally
produces usually eight actinosporean spore stages
(actinospores) within a pansporocyst (An assemblage
of several sporocysts).
ANNELID

9.  After mature actinospores are released from their hosts they float in the
water column.
 Upon contact with skin or gills of fish, sporoplasms penetrate through
the epithelium, followed by development of the myxosporean stage.
 Myxosporean trophozoites are characterized by cell-in-cell state, where
the secondary (daughter) cells develop in the mother (primary) cells.
 The presporogonic stages multiply, migrate via nervous or circulatory
systems, and develop into sporogonic stages. At the final site of
infection, they produce mature spores.
 Examples of Myxosporean genera are Kudoa, which attacks
fish muscle and Myxobolus which attacks the hearts of
freshwater fishes.