Collocyte is a term variously applied in botany and zoology to cells that produce gluey substances, or that bind or capture prey or assorted objects by securing them with gluey materials and structures, or that simply look smooth and gelatinous. Literally the word means "glue cell", and it has a number of poorly distinguished synonyms, such as ''colloblast''.Harmer, Sir Sidney Frederic; Shipley, Arthur Everett et alia: The Cambridge natural history Volume 1, Protozoa, Porifera, Coelenterata, Ctenophora, Echinodermata. Macmillan Company 1906

Use in Botany

In English the term "collocyte" (or, less formally, "glue cell") is uncommon in botanical publications. It appears more often in French texts; however, it sometimes is used in referring to individual cells in

ground tissue The ground tissue of plants includes all tissues that are neither dermal nor vascular. It can be divided into three types based on the nature of the cell walls. # Parenchyma cells have thin primary walls and usually remain alive after they beco ...

s of types characterised as

collenchyma The ground tissue of plants includes all tissues that are neither dermal nor vascular. It can be divided into three types based on the nature of the cell walls. # Parenchyma cells have thin primary walls and usually remain alive after they bec ...

Use in Zoology

In zoology the word "collocyte" applies to several different types of cell in very different

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

, and there are a few similar terms used confusingly or interchangeably, such as colloblast. Some of the terms refer to specialised subject matter, so from time to time variations and inconsistent definitions have been coined independently in niche disciplines. For example, ''

glial cells Glia, also called glial cells (gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. They maintain homeostasis, form myel ...

'' sometimes are called "glue cells" but have little in common with other types of so-called glue cells. Apart from such difficulties, "glue cells" of various types commonly occur in taxa of animals that are practically unrelated to each other, and in such cases they are as a rule non-homologous and differ profoundly in their

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vi ...

and function. This suggests that distinct terms should be allocated to the different types. The problem is so marked that to avoid confusion many workers are abandoning traditional terms in favour of new words.

Collocytes in Tunicata

Among the taxa of animals that have some form of cells that might be classed as collocytes, are the larvae of

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

forms of

Tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ...

s. Near the head end, most of those have collocytes with which they permanently fasten themselves to the substrate.

Collocytes in Ctenophora

Perhaps the most striking and celebrated examples of collocytes are those of the Ctenophora (comb jellies). The Ctenophora use their colloblasts or collocytes in hunting and gathering food, in much the same way as members of the

Cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that ...

use

cnidocyte A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this c ...

s; they keep the cells in a retracted form until they deploy them for securing prey. In keeping with their food capturing function, the collocytes sometimes are called "lasso cells", but as is to be expected of common names, the term is not precise and is variously applied to both colloblasts and cnidocytes. The retracted mechanism is kept coiled in the Ctenophora, as opposed to inside out in the Cnidaria. The Cnidaria

evert Evert is a Dutch and Swedish short form of the Germanic masculine name "Everhard" (alternative Eberhard).Evert
at the

their stings to penetrate the prey, but the Ctenophora eject microscopic balls of adhesive mucus that stick to the prey externally, trailing threads that as a rule do not lose attachment to the parent colloblast. The structure of these specialized cells is extremely complex and varies among ctenophore species. Their mechanisms are still under study.

C''ollenocytes''

In some organisms collocytes that attach the animal to substrates must be able to release their grip as well as establish it. Commonly, though not always, this requires the ability to dissolve the adhesive substances after the adhesion has been achieved. When a glandular structure has the ability to perform both the adhesion and the dissolving of the adhesive, it is called a duo-gland This is a very common requirement and examples occur in

Platyhelminths The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegmen ...

, both parasitic and free-living,Lengerer B, Pjeta R, Wunderer J, Rodrigues M, Arbore R, Schärer L, Berezikov E, Hess MW, Pfaller K, Egger B, Obwegeser S, Salvenmoser W, Ladurner P. Biological adhesion of the flatworm Macrostomum lignano relies on a duo-gland system and is mediated by a cell type-specific intermediate filament protein. Front Zool. 2014 Feb 12;11(1):12. doi: 10.1186/1742-9994-11-12. Annelida,

Echinoderm An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...

ata and other phyla. In some organisms the adhesion it affords is so remarkably reversible that it is used as the basis of locomotion over solid surfaces.

Confusion between collocytes and collencytes

Another class of apparently similarly-named cells, "collencytes" occurs in sponges, but in this case there is little to do with adhesion. The term was derived from the tissue in which the cells occur: collenchyma. The name

in turn was borrowed from botany because of a fancied, essentially irrelevant, resemblance between sponge tissue and a particular class of ground tissue in plants. The collencytes are one of the classes of component cells of the sponges' tissue, loose mesenchyme between the ectoderm and the endoderm in the body wall. The functions of the collencytes are not yet fully understood; they are branched

amoeboid An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopo ...

cells and appear to produce collagen and play roles in forming sponge spicules. It even has been proposed that they have primitive nerve-like physiologic roles.LI Hui, ZHANG Xiao-Yun, WANG An-Tai. Exploration on primordial nervous substances in sponges. Current Zoology(formerly Acta Zoologica Sinica), Dec. 2005, 51(6):1091 - 1101

References

{{Reflist, 2 :Ctenophora Histology