Cestode glossary

acaudate
condition of a metacestode characterized by the absence of tail-like cercomer Antonym: caudate
acetabulate scolex
scolex with four lateral muscular membrane-bound attachment organs (i.e., bothridia or acetabula) Synonym: tetrafossate scolex as in Wardle & McLeod, 1952; Hoberg et al., 2001 Remarks: for the purposes of the present database, we have adopted the interpretations of Caira et al. (1999) who considered bothridia having principally the same organization as acetabula
acetabulum
muscular membrane-bound attachment organ, usually cup-shaped, sunk within the surface of the scolex and consisting of muscular fibres perpendicular to the tegument and extending between the tegument and the bounding membrane (modified from Wardle & McLeod, 1952; Caira et al., 1999)
acraspedote
configuration of the strobila (or proglottides), in which the posterior portion of the proglottis does not overlap the anterior portion of the next proglottis Synonym: amphidote Antonym: craspedote
adult
sexually mature stage in the life cycle characterized by the presence of functional reproductive organs containing fully developed gametes
amphidote
See preferred term: acraspedote
anapolysis
mode of strobilar development characterized by the non-detachment of gravid proglottides Antonym: apolysis
apical organ
organ at the anterior extremity of the body of the adult and/or metacestode, consisting of muscular and/or glandular tissue, and typically specialized in an attachment function
apolysis
mode of strobilar development characterized by the detachment of terminal gravid proglottides Antonym: anapolysis
armatetrathyridium
See preferred term: fimbriocercus
asexual reproduction
mode of reproduction in which new individuals are produced without participation of gametes
autotomicrocercus
See preferred term: urocysticercoid
bladder
fluid-filled cavity in metacestodes of some Trypanorhyncha, Tetraphyllidea and Cyclophyllidea
bothriate scolex
scolex with two, rarely four or six, lateral muscular attachment organs called bothria Synonym: difossate scolex as in Wardle & McLeod, 1952 and in Hoberg et al., 2001
bothridium (pl. bothridia)
muscular membrane-bound attachment organ on the scolex consisting of muscular fibres perpendicular to the tegument and extending between the tegument and the bounding membrane (modified from Caira et al., 1999)
bothrium (pl. bothria)
muscular attachment organ, not membrane-bound, not consisting of radial muscular fibres and situated on the ventral and dorsal surface of the scolex (modified from Caira et al., 1999)
budding
mode of asexual reproduction in which somatic part of a parental organism detaches and forms new individual(s)
calcareous corpuscles
corpuscles found in many cestodes, especially in larval stages, and made up mostly of calcium carbonate, magnesium carbonate and a hydrated form of calcium phosphate embedded in an organic matrix (modified from Slais, 1966)
caudate
condition of a metacestode characterized by the presence of tail-like cercomer Antonym: acaudate
caudate diplocysticercoid
cysticercoids in which the scolex is enveloped by two layers of larval tissue, the internal one is the ‘real’ cyst and the external one is formed by part of the cercomer while the remaining part of the cercomer is tail-like Synonym: ramicercus sensu Chervy, 2002 Remarks: we consider ‘floricercus’ (see Bondarenko & Kontrimavichus, 1976) as a modification of caudate diplocysticercoid in which the most external envelope is not totally closed
cercocysticercoid
caudate cysticercoid (from Chervy, 2002)
cercomer
most posterior part of the body in metacestodes, separated from the anterior body part by constriction formed by circular muscle delimiting small cavity containing the orifice(s) of the osmoregulatory system. The cercomer can be tail-like or form additional protective envelopes surrounding the remaining part of the body of the metacestode
cercoscolex
See preferred term: merocercoid
cladothyridium
See preferred term: merocercoid
coenurus (pl. coenuri)
metacestode of some species of Taenia (Cyclophyllidea), which consists of a large fluid-filled cyst containing many scoleces formed asexually from the internal germinative membrane (i.e., endogenous scolex development)
coracidium (pl. coracidia)
developmental stage of some cestodes, representing an oncosphere and surrounding embryonic envelope (i.e., embryophore), which is ciliated and is thus adapted for swimming after emergence from the egg
craspedote
configuration of the strobila (or proglottides), in which the posterior portion of the proglottis (i.e., velum) overlaps the anterior portion of the next proglottis Antonym: acraspedote, amphidote
cross-fertilisation
mode of sexual reproduction in which new individuals are produced as a result of syngamy of gametes from different parents Synonym: out-crossing Antonym: self-fertilisation, selfing
cysticercoid
metacestode with primary lacuna (sometimes not distinct), scolex retracted within solid cyst, with cercomer or reduced cercomer (modified from Chervy, 2002)
cysticercus (pl. cysticerci)
metacestode with primary lacuna (sometimes not distinct) and a single invaginated scolex (from Chervy, 2002)
decacanth
See preferred term: lycophore
definitive host
host harbouring the adult stage Synonym: final host
dioecy
See preferred term: gonochorism
diplocyst
See preferred term: diplocysticercoid
diplocysticercoid
cysticercoid in which the scolex is enveloped by two layers of larval tissue, the internal one is the ‘real’ cyst and the external one is formed by the cercomer (modified from Chervy, 2002) Synonym: diplocyst
echinococcus
See preferred term: hydatid
egg
embryo and the surrounding protective and nutritive tissues (whether in uterus of gravid cestode or in the environment)
egg capsule
common envelope embedding an aggregation of eggs or an additional envelope around a single egg situated externally to the outer shell
embryophore
layer of cellular origin covering the oncosphere and derived from the inner envelope of the egg
endogenous scolex development
mode of asexual reproduction in some types of metacestodes (hydatids, coenuri and, probably, some cysticercoids), characterized by the formation of new scoleces (i.e., protoscoleces) developing toward the interior of the parental organism
endopolygeny
mode of asexual reproduction in which a mother metacestode (in Mesocestoides) produces internally daughter metacestode(s) Synonym: internal budding
enteral
site of parasite (location) in the alimentary tract of the host Antonym: parenteral
euparatenic host
paratenic (and, therefore, facultative) host, in which metacestodes do not undergo any development but remain infective for the definitive host (modified from Bozkov, 1982)
euryxeny
condition of host specificity for a parasite species that can develop in a wide range of host species, which are ecologically similar but phylogenetically distant (modified from Euzet & Combes, 1980) Synonym: polyxeny sensu Odening, 1976
evagination
process by which metacestodes with invaginated scolex adopt a functional configuration when reaching the definitive host
excystment
process by which metacestodes with retracted scolex adopt a functional configuration when reaching the definitive host
exogenous scolex development
mode of asexual reproduction in metacestodes, characterized by the formation of new scoleces developing toward the exterior, as continuation of the external wall of the parental organism
fecundity
reproductive potential of the whole organism in term of egg production (roughly assessed by the number of eggs produced per proglottis, multiplied by the number of proglottides)
fimbriocercus
cysticercus characterized by an elongated unsegmented body Synonym: armatetrathyridium (after Chervy, 2002)
fissioning
mode of asexual reproduction in which an organism splits itself in two, almost identical, parts
flame cell
ciliated cell specialized for excretion and osmoregulation, being a part of the protonephridium
gamete
haploid and mature reproductive cell; spermatozoon in male, ovum in female
genital pore
external openings of the male and female reproductive systems or a common opening of the two genital systems
gonochorism
state of strobilar development characterized by the possession of gonads of only one sex (male or female) Synonym: dioecy Antonym: hermaphroditism, monoecy
gravid
for cestode worm or individual proglottis, containing developed eggs, ready to be released into environment
hermaphroditism
state of strobilar development characterized by the presence of both male and female reproductive organs in the same organism (not necessarily at the same time) Synonym: monoecy Antonym: gonochorism, dioecy
heteroxeny
condition of host alternation for a parasite species that uses more than one host species to complete its entire life cycle (from Odening, 1976) Antonym: homoxeny
hexacanth
See preferred term: oncosphere
homoxeny
condition of host alternation for a parasite species that only uses one host species to complete the entire life cycle (from Odening, 1976) Antonym: heteroxeny
hydatid
metacestode of some species of the genus Echinococcus (Cyclophyllidea) which is a large fluid-filled cyst containing multiple invaginated scoleces and daughter cysts that also contain multiple invaginated scoleces Synonym: echinococcus
hyperapolysis
early detachment of proglottides that leads to an independent existence while maturing and/or developing ripe eggs
inner egg envelope
envelope surrounding the oncosphere, situated internally to the outer egg envelope, formed as result of the fusion of three mesomeres (i.e., having three nuclei in a syncytial organization) and giving rise to the embryophore
intermediate host
obligatory host in the life cycle, in which metacestodes undergo development and become infective for the definitive host or for another intermediate host (modified from Odening, 1976)
invaginated
for scolex, being withdrawn within the body of the metacestode by turning outside-in, in a way which renders its apex the bottom of a cavity while the external walls of the scolex become the internal walls of the same cavity. Reaching the definitive host, a metacestode with invaginated scolex evaginates
lacunate
condition of metacestodes characterized by the presence of a primary lacuna
larva
early stage of development that performs metamorphosis turning into a metacestode (Freeman, 1973). However, the term is also widely used for stages in intermediate and paratenic hosts (i.e., for metacestodes, as in Chervy, 2002) See preferred term: oncosphere, lycophore, metacestode
lycophore
early stage of development of some cestodes (Amphilinidea and Gyrocotylidea), provided with 10 embryonic hooks, which is ciliated and thus adapted for swimming after emergence from the egg, and undergoing metamorphosis after penetrating into the host
merocercoid
metacestode lacking a primary lacuna, in which scolex is invaginated (modified from Chervy, 2002) Synonym: tetrathyridium, cladothyridium, cercoscolex
merocercus
See preferred term: plerocercus
metacestode
all developmental stages between the oncosphere/lycophore and the adult (egg-producing stage), and therefore occurring in the intermediate or paratenic host(s). The etymology of the term is from ‘a changing cestode’ (Wardle & McLeod, 1952; Freeman, 1973)
metaparatenic host
kind of paratenic (and, therefore, facultative) host, in which metacestodes undergo development typical for the definitive host but do not reach maturation or egg production (modified from Bozkov, 1975)
microcysticercoid
cysticercoid with a vestigial cercomer (modified from Chervy, 2002)
monocysticercoid
cysticercoid in which the cercomer forms additional envelope around the cyst, which may disintegrate into globules or become granular in appearance (modified from Chervy, 2002) Synonym: monocercus
monoecy
See preferred term: hermaphroditism
monofossate scolex
scolex with ‘a single apical sucker only’. Term to be avoided because it is connected with the presence of an apical organ while the other two conditions (i.e., bothriate or difossate and acetabulate or tetrafossate) reflect the presence of lateral attachment organs
monoxeny
See preferred term: oioxeny
monozoic
with a single set of reproductive organs; used for the body organization of Gyrocotylidea, Amphilinidea and Caryophyllidea Antonym: polyzoic
neck
for polyzoic cestodes, undifferentiated portion of the worm between the scolex and the strobila, which contains stem cells that give rise to the proglottides Synonym: proliferation zone, germinative area, collum, pars proliferans scolecis
neoteny
process of development in which sexual maturation in the definitive site and host is associated with retention of some larval characters
oioxeny
condition of host specificity for a parasite species that can only develop in a single host species (from Euzet & Combes, 1980)
oligolecithal egg
egg formed with only one or two vitellocytes associated with each zygote (from Swiderski & Xylander, 2000)
oligoxeny
See preferred term: stenoxeny
oncosphere
early stage of development, common to all eucestodes, provided with six embryonic hooks and undergoing metamorphosis after penetrating into a parenteral site in the (first/only) intermediate host to become a metacestode
oocyte
See preferred term: ovocyte
ootype
organ of the female reproductive system that is typically surrounded by Mehlis’ gland, connected with two ingoing ducts (one coming from the vitellarium and another formed after the fusion of the ducts coming from seminal receptacle and from ovary) and with one outgoing duct leading to the uterus
operculum
lid or cap-like structure at the end of eggs in some cestodes
out-crossing
See preferred term: cross-fertilisation
outer egg envelope
envelope surrounding the inner egg envelope, formed as a result of fusion of two macromeres (i.e., having two nuclei in a syncytial organization)
oviduct
short duct that carries ova from the ovary to the ootype; often fusing with the seminal duct carrying spermatozoa from the seminal receptacle and forming a common duct leading to the ootype
oviparity
mode of embryonic development, in which the embryo does not develop in utero and hatches from protective envelopes outside the parental organism (modified from Tinsley, 1983)
ovocyte
in female gametogenesis, precursor of ovum Synonym: oocyte
ovoviviparity
mode of embryonic development, in which the embryo hatches from protective envelopes within the parental organism and develops in utero (modified from Tinsley, 1983)
ovum (pl. ova)
mature but non-fertilized gamete in female
paedogenesis
process of development resulting in sexual maturation by an organism in a (morphologically) larval state. It can be by means of neoteny or progenesis
paraparatenic host
paratenic (and, therefore, facultative) host, in which metacestodes undergo development and are infective for the definitive host (modified from Bozkov, 1975)
paratenic host
facultative intermediate host, in which metacestodes infective to the definitive host may survive for indefinite period (modified from Odening, 1976) Synonym: reservoir host
parenchymatous capsule
envelope surrounding either a single egg and situated externally to outer shell or aggregation of eggs and having an origin from parenchyma
parenteral
site of parasite (location) outside the alimentary tract of the host Antonym: enteral
parthenogenesis
mode of sexual reproduction in which new individuals develop from a female gamete (i.e., ovum) without fertilisation from a male gamete (i.e., spermatozoon)
paruterine organ
organ appearing as fibrous or granular appendage to the uterus that usually receives the ripe eggs and retains them in a common capsule with protective and/or propagative function
plerocercoid
metacestode without primary lacuna, scolex not retracted, not withdrawn Synonym: merocercus, blastocyst, tentaculoplerocercoid
plerocercus
metacestode without primary lacuna, scolex retracted
polycysticercoid
See preferred term: monocysticercoid Remarks: term introduced by Chervy (2002) to mark ‘polycephalic diplocysticercoid (= polycyst)’ of Polycercus; however, the examination of the primary literature suggests that the ‘polycyst’ of Polycercus is in fact an aggregation of numerous monocysticercoids embedded in a common envelope consisting of host tissue (Genov, 1963)
polylecithal egg
egg formed with more than two vitellocytes associated with the zygote (from Swiderski & Xylander, 2000)
polyvalent host
host species acting as more than one host in the life cycle (e.g., intermediate and definitive host; intermediate and paratenic host)
polyxeny
See preferred term: euryxeny
polyzoic
with multiple sets of reproductive organs (i.e., having strobila consisting of two or more proglottides) Antonym: monozoic
primary lacuna (pl. primary lacunae)
sinus between cells that develops in the early stage of the morphogenesis of metacestodes of some Cyclophyllidea
procercoid
metacestode without primary lacuna and scolex
progenesis
process of development in which sexual maturation occurs precociously (i.e., in a larval site in an intermediate host)
proglottis (pl. proglottides)
part of strobila containing a set of reproductive organs. In most of the cases, there is coincidence between internal ‘proglottisation’ and external ‘segmentation’ of strobila and in these cases ‘proglottis’ and ‘segment’ are synonyms; however, in particular groups (e.g. Spathebothridea) one segment can contain a number of proglottides
proglottisation
process of formation of proglottides (i.e., repetition of reproductive organs), no matter if it is associated or not with external segmentation
protandry
condition in a sequential hermaphrodite in which male gonads mature before female gonads Antonym: protogyny, proterogyny
proterogyny
See preferred term: protogyny
protogyny
condition in a sequential hermaphrodite in which female gonads mature before male gonads Synonym: proterogyny Antonym: protandry
protonephridium
unit of the excretory (osmoregulatory) system consisting of flame cell(s) and outgoing duct(s)
protoscolex (pl. protoscoleces)
juvenile scolex formed asexually in Echinococcus spp. (Cyclophyllidea), and lacking fully developed hooks
protruded
for scolex, being outside the body, in a configuration similar to the adult
pseudoscolex
anterior end of the strobila modifies to function as an attachment organ
pyriform apparatus
modification of the embryophore in anoplocephalid cestodes assuming the shape of a pear, probably with protective and propagative functions
ramicercus
See preferred term: caudate diplocysticercoid
ramicysticercoid
cysticercoid with branching cercomer
retracted
for scolex, being withdrawn within the body of the metacestode (in a cyst) such that it keeps its definitive configuration (i.e., the scolex itself is not invaginated). Reaching the definitive host, a metacestode with retracted scolex is excysted
rostellum
a modification of the apical organ, usually associated with a crown of hooks
scolex (pl. scoleces)
anterior part (‘head’) of the cestodes specialized for attachment at the gut wall of the host
segment
externally distinct unit of the strobila defined by transverse grooves or partitions, which may contain one (typically) or more proglottides
segmentation
process of division of the strobila into externally distinct units
self-fertilisation
mode of sexual reproduction in which new individuals are produced by syngamy of gametes from the same parent (thus including cross inseminations between proglottides of the same strobila) Synonym: selfing Antonym: cross-fertilisation, out-crossing
selfing
See preferred term: self-fertilisation
sexual maturity
condition of an organism being able to reproduce sexually (i.e., having functioning reproductive organs containing fully developed gametes)
sexual reproduction
mode of reproduction in which new individuals are produced by means of gametes (and, therefore, including parthenogenesis) Antonym: asexual reproduction
staphylocyst
See preferred term: staphylocysticercoid
staphylocysticercoid
polycephalic metacestode developing in the form of a bunch of grapes each representing a cysticercoid (from Chervy, 2002) Synonym: staphylocyst
stenoxeny
condition of host specificity for a parasite species that develops in phylogenetically related species of host, those from the same genus for example (modified from Euzet & Combes, 1980) Synonym: oligoxeny sensu Odening, 1976
strobila (pl. strobila)
body part of polyzoic cestodes consisting of proglottides
strobilation
process of formation of the strobila
strobilocercoid
cysticercoid containing within the cyst, in addition to scolex and neck, also a segmented body part (‘metacestode strobila’)
strobilocercus
cysticercus containing, in addition to scolex and neck, also a segmented body part (‘metacestode strobila’)
syncytium
cellular structure formed by fusion of cell bodies but with retention of separate nuclei
syngamy
process of fusion of ovum and spermatozoon cells into a zygote
tanned egg
egg with a hard inert shell, formed by sclerotin, a mixture of quinone and proteins
tentaculoplerocercoid
See preferred term: plerocercus
tetrafossate scolex
See preferred term: acetabulate scolex
tetrathyridium
metacestode of Mesocestoides developing in vertebrate host and characterized by invaginated scolex and lack of cercomer Synonym: merocercoid
urocyst
See preferred term: urocysticercoid
urocysticercoid
polycephalic metacestode exhibiting a mycelium-like development from which cysticercoids bud off (from Chervy, 2002) Synonym: urocyst, autotomicrocercus
uterine capsule
envelope surrounding single egg and situated externally to outer shell or aggregation of eggs and having an origin from uterine wall, either in gravid uterus or in environment
uterus
organ of the female reproductive system, connected with the ootype by the uterine duct, storing fertilized eggs and providing nutrients and protection during the development
vegetative reproduction
See preferred term: budding
velum
posterior part of a proglottis, overlapping subsequent proglottis
viviparity
mode of embryonic development, in which the embryo, without any protective envelope, develops in utero within the parental organism (modified from Tinsley, 1983)
zygote
diploid cell that results from the fusion of an ovum (female gamete) and a spermatozoon (male gamete)
References
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