Trichocysts

Trichocysts are cytoplasmic organelles found in some protists ( ciliates - paramecia , cnidosporidia ) and serving them as defense or attack organs, capable of "shooting" with mechanical or chemical irritation. Trichocysts are located in the cytoplasm perpendicular to the surface of the body and, as a rule, have the appearance of small spindle-shaped rods, which, when exposed to mechanical, chemical or electrical stimuli, are thrown out and take the form of long threads.

Trichocysts in different types of protists have a different shape, and one species can have several types of trichocysts. For example, ciliates are characterized by the presence of spindle-shaped trichocysts, which are elongated (from 2 to 6 micrometers) protein bodies of a paracrystalline structure, equipped with a dense tip and intended for protection: when fired, they are able to stretch into a thread with a tip at a length of 20 to 60 micrometers. Ciliates also have mucocysts (protrichocysts) that do not have a tip and take the form of a swollen gelatinous substance with a mesh structure when fired, rhabdocysts are rod-shaped trichocysts that are completely pushed out; poisonous and intended solely for attack toxicists, consisting of a long capsule with a straight tube that is screwed in and when attacked, firing, turns out; small extrusions at the ends of the tentacles called haptocysts, which consist of a short tube and ampoule; cnidocysts (formerly called stinging capsules) - trichocysts with a tubular thread twisted inside, having a spherical or oval shape and turning out when irritated.

In flagellates, toxicists characteristic of predatory ciliates, rhabdocysts and haptocysts are absent, but there are shadowobolocysts, which are a protein tape, as if rolled up into a roll, which, when irritated, turns out. Knidocysts of knizosporidia (the so-called polar capsules) inherent in spores, when fired, ensure the attachment of spores to the host body.