centimeter n. [L. centum, hundred; metron, measure] One hundredth (.0l) part of a meter or two fifths (0.3937) of an inch. Abbrev. cm. see meter.
centrad adv. [Gr. kentron, center; L. ad, toward] Toward the center or interior.
centradenia n. [Gr. kentron, center; aden, gland] (CNID: Hy-drozoa) A type of siphonophore hydroid colony.
central area 1. (MOLL: Polyplacophora) The upper surface of an intermediate valve, lying centrally, and sometimes differing in sculpture from the lateral areas. 2. (NEMATA: Se-cernentea) The nonstriated region around the vulva in the Meloidogyne perineal pattern.
central cell (PORIF) A cell located in the cavity of a choanocyte chamber.
central nervous system In invertebrates, a system to which the sensory impulses are transmitted and from which motor impulses pass out. a. In radially symmetric animals, structured in the form of one or two rings. b. In elongate animals, usually consists of an anterior bilobed cerebral ganglion (brain), and paired longitudinal ventral cords that are usually connected by the circumesophageal nerve ring.
central region (ARTHRO: Insecta) The costal region of a wing.
central symmetry system (ARTHRO: Insecta) The median field of the moth wing pattern delimited basally and distally by the light central line of the transverse, anterior and posterior lines.
central tube (NEMATA) The sclerotized cylindrical axis of the head skeleton of nematodes, through which the stylet extends during feeding.
centric fusion The fusion of two acrocentric chromosomes to form a single metacentric chromosome through translocation and as a rule, the loss of a centromere.
centrifugal a. [Gr. kentron, center; L. fugare, to flee] 1. Turning from or being thrown away from the center. 2. Moving toward the periphery, as nerve impluses.
centriole n. [Gr. kentron, center] Either of the two minute spherical bodies in a cell center that migrates to opposite poles during cell division and serves to organize the alignment of the spindles.
centripetal a. [Gr. kentron, center; L. petere, to move toward] Turning inwardly from the outside or periphery; toward the center. see centrifugal.
centripetal canal (CNID) One of numerous blind canals running from the circular canal toward the apex of the bell in certain jellyfish.
centris n. [L. centrum, sting] (ARTHRO: Insecta) In Hymenop-tera, the sting.
centrodorsal a. [Gr. kentron, center; L. dorsum, back] 1. Referring to central and dorsal. 2. (ECHINOD: Crinoidea) Pertaining to a cirriferous ossicle, fused or semifused, attached to the theca.
centrogenous a. [Gr. kentron, center; gennaein, to produce] 1. Growing from the center. 2. (PORIF) A spicule growing from a common center.
centrolecithal egg (ARTHRO) A type of arthropod egg in which the nucleus is located centrally in a small amount of non-yolky cytoplasm surrounded by a large mass of yolk until fertilized; when nuclear divisions begin the nuclei migrate to the periphery to proceed with superficial cleavage, with the yolk remaining central. see isolecithal egg, mesolecithal egg, telolecithal egg.
centromere n. [Gr. kentron, center; meros, part] The part on the chromosome where it becomes attached to the spindle.
centrophormium n. [Gr. kentron, center; phormis, basket] Round basket-like Golgi bodies.
centroplasm see centrosome centrosome n. [Gr. kentron, center; soma, body] A specialized area of condensed cytoplasm that contains the centrioles at the beginning of mitosis; also called centrosphere, cyto-centrum, microcentrum, attraction sphere, and paranuclear body.
centrosphere see centrosome centrotylote a. [Gr. kentron, center; tylos, knob] (PORIF) In diactinal monoaxons, having the knob near the middle of the shaft of a spicule.
centrum n.; pl. -trums [Gr. kentron, center] A center or central mass.
cephalad adv. [Gr. kephale, head; L. ad, toward] Toward the head or anterior end; rostrad. see caudad.
cephalaria n. [Gr. kephale, head; -aria, a thing like] (ARTHRO: Insecta) In a generalized insect, the alaria present on each lateral margin of the prescutum anterior to the pre-phragma.
cephalate a. [Gr. kephale, head] Having a head or head-like structure.
cephaletron n. [Gr. kephale, head; etron, belly] (ARTHRO: Chelicerata) The anterior body region of Limulidae, the horseshoe crabs.
cephalic a. [Gr. kephale, head] Pertaining to the head or anterior end.
cephalic bristles (ARTHRO: Insecta) In Diptera, specialized bristles occurring on the head.
cephalic cage (ANN: Polychaeta) Long forwardly directed setae encircling the mouth.
cephalic capsule (nemata) An internal modification of the cephalic cuticle forming an endoskeletal helmet, often posteriorly delimited by a distinct groove on the exterior cuticle.
cephalic constriction (ARTHRO: Crustacea) In Myastacocarida, a constriction delimiting anterior antennulary part of the head from the posterior part.
cephalic flexure (ARTHRO: Crustacea) In Decapoda, forward, or occasionally upward, deflection of the anterior sterna.
cephalic foramen (ARTHRO: Insecta) The posterior or occipital foramen of the head through which the alimentary canal and other organs pass.
cephalic framework (NEMATA: Secernentea) A subcuticular framework that supports the lip region, and to which are attached the stylet protractor muscles.
cephalic gland (ARTHRO: Insecta) A gland opening on to the labium and connecting with the ventral tube by a groove in the cuticle in the ventral midline of the thorax, that secrets moisture to aid walking on dry surfaces.
cephalic grooves/slits (NEMER) Deep or shallow furrows, lined with a ciliated epithelium, that occur laterally on the sides of the head; thought to be chemosensory.
cephalic heart (ARTHRO: Insecta) In Odonata, a specialized pulsating organ that exerts pressure against the egg-shell in hatching and forces out a cap-like operculum; a pulsating organ.
cephalic hood (MOLL: Bivalvia) A chitinous covering protecting the anterior adductor muscle at a young burrowing stage.
cephalic incision (NEMATA) Anterior extensions of the cephalic suture dividing the posterior part of the capsule into lobes.
cephalic lobes 1. (ARTHRO: Insecta) In embryology, the region of the prostomium, and usually that of the tritocerebral somite. 2. (NEMER) Brain lobes on the expanded anterior region.
cephalic pole (ARTHRO: Insecta) An elongated egg in the ovariole aligned with the head of the parent.
cephalic region Pertaining to, on, in, or near the head.
cephalic rim (ANN: Polychaeta) A flange encircling the head.
cephalic salivary glands (ARTHRO: Insecta) A pair of glands lying against the posterior wall of the head of bees, that unite with the thoracic salivary gland to form a common duct. see postocellar glands.
cephalic setae (nemata) Setae-like sensilla of the outer of three circlets around the anterior neck region or mouth.
cephalic shield 1. (ARTHRO: Crustacea) A chitinous, somewhat calcified covering of the head region formed of fused ter-gites of cephalic somites, commonly having pleura. 2. (MOLL: Gastropoda) In Opisthobranchia, an expanded thickening of the dorsal surface of the head that may at times extend dorsally over the back.
cephalic somite (ARTHRO: Crustacea) A unit division of the cephalic region usually recognized as one of five somites that bear distinctive paired appendages; a cephalomere.
cephalic stomodeum (ARTHRO: Insecta) That part of a sto-modeum contained in the head.
cephalic suture (NEMATA: Adenophorea) The posterior delimitation of the cephalic capsule in marine nematodes.
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