ectoderm (ektoderm)

[ + δέρμα, skin: see derm.] The completed outer layer of cells, or outer blastodermic membrane, in all metazoan animals, formed by the cells of the epiblast, and primitively constituting the outer wall of the whole body, as the endoderm does that of the body-cavity; an epiblast, ecto blast, or external blastoderm. The term is chiefly used in embryology, or of certain lower animals whose bodies consist e entially of an outer and an inner layer, and not as a synonym of the epidermis or cuticle of the higher animals. See cut under gastrula. ectodermal (ek-to-der'mal), a. [ al.] Pertaining to the ectoderm; consisting of ectoderm: as, the ectodermal layer of a cœlenterate. The ovary bursts its ectodermal covering. W. B. Carpenter, Micros., § 515. primaries, a long cuneate tail of 12 tapering acuminate feathers, wing-coverts with black spots, party-colored tail- feathers, an iridescent neck, and the sexes distinguishable by color. E. migrator i us is the common wild pigeon or pa enger-pigeon of North America. See cut under pas- senger - pigeon . ectoplasm (ek'tō-plazm), n. [ ἐκτός , with- out, + πλάσμα, a thing formed, πλάσσειν , form.] 1. In zoöl ., the exterior protoplasm or sarcode of a cell; the ectosarc: applied to the denser exterior substance of infusorians and other uni- cellular organisms, or of a free protoplasmic body, as a zoöspore. In the Infusoria, which are covered by a firm cuticle, there is a central semifluid ma of sarcode (endoplasm) which is distinct from the more compact peripheral layer of sarcode ( ectoplasm ). Claus , Zoology (trans.), I. 54. 2. In bot ., the outer hyaline layer or film of the protoplasmic ma within a cell. Some of the pathogenous bacteria are accustomed to develope and multiply without the body, while others only do so within it. The former kind we may describe ectoplasmic (ek-to-plaz'mik), a. [ ectoplasm as ectogenous , the latter as endogenous. +-ic.] Pertaining to or consisting of ecto- ectoplastic (ek-to-plastik), a . Same as ecto- plasmic. The differentiation of this cortical substance (which is not a frequent or striking phenomenon in ti ue-cells) may be regarded as an ectoplastic (i. e., peripheral) modifi- cation of the protoplasm, comparable to the entoplastic (central) modification which produces a nucleus. ectopopliteal (ek"to-pop-lite-al), a . ἐκτός , outside, + L. poples ( poplit- ), hock, knee: see popliteal .] In an at ., situated upon the outer side of the popliteal space or region: as, the ec- to popliteal nerve. Ectoproct a (ek-to-prok'tä), n . pl . [NL., neut. pl. of ectoproct us .] A division of the Polyzoa established by Nitsche, characterized by hav- ing the anus outside of the circlet of tentacles: opposed to Endoproct a . See the extract. In the Ectoproct a , the endocyst consists of two layers, an outer and inner; of which the former is the representative of the ectoderm in other animals. The latter lines the walls of the per i visceral cavity, and is re- flected thence, like a peritoneal tunic, over the tentacular sheath and into the interior of the tentacula, whence it is continued on to the alimentary canal, of which it forms the external investment. The endoderm, which lines the alimentary canal, is of course continuous, through the oral opening, with the ectoderm. ectoproct ous (ek-to-prok'tus), a. [ ecto- proctus, πρωκτός , the anus, posteriors.] Pertaining to or having the characters of the Ectoproct a : specifically ap- which have the anus situated outside the cir- plied to those polyzoans, as the Gymnolæmat a , clet of tentacles: opposed to endoproct ous . It has been pointed out that the characteristic polypide of the ectoproct ous Polyzoa is a structure developed from the cystid. ectopterygoid (ek-top-ter'i-goid), a. and n. [ ectopterygoideus , q. v.] I. a. Pertaining to the external pterygoid bone or muscle. II. n. 1. An external pterygoid bone; one of the lateral bones of the palate of some ani- mals, as reptiles. It is highly developed, for in- In typical fishes, the external of two bones just behind the palatine, generally called pterygoid. See cut under palato - quadrate .-3. In an at ,, the ectopterygoid muscle. ectopterygoideus (ek-top-ter-i-goi'de-us), n.; pl. ectopterygoidei (-1). [NL., ἐκτός , side, + NL. pterygoideus : see pterygoid .] an at., the external pterygoid muscle. See pterygoideus . ectopy (ek'tō-pi), n. Same as ectopia . ectosarc (ek'tō-särk), n. [ ἐκτός , outside, + σάρξ (σαρκ-), flesh.] The ectoplasm of a protozoan; the exterior substance of the body of an animal of low organization, as an ameba er, denser, tougher, or otherwise modified pro- to plasm which forms an envelop of the body, as differentiated from the interior substance or contents. The term is used chiefly in connection with amœbas or other rhizopods, in which, though there may be no definite cell-wall, the outer sarcode is differentiated in some way from the inner substance, or endosarc. ectosarc ode (ek-to-särkōd), n. Same as ecto- Sollas , Encyc. Brit., XXII. 415. [ ectosphenoid (ek-to-sfēʼnoid), n. without, + σφηνοειδής , wedge-shaped: noid .] Same as ectocuneiform. [Rare.] ectosporous (ek-to-spo'rus), a. [ σπόρος , seed: see spore .] Forming spores externally; exosporous. ectosteal (ek-tos'te-al), (ek-tos'te-al), a . [ ὀστέον , bone, + -al . ] Relating to or situated on the outside of a bone; proceeding from without inward, as a growth of bone. ectosteally (ek-tos'te-al-i), adv . In an ectos- teal manner or position. of o ification of cartilage which begins in or immediately under the perichondrium; also, growth of bone from without inward; perios- teal o ification. ectothecal (ek-to-the'kal), a. [ ἐκτός , out- ecto side, + θήκη , case: see theca .] In bot ., having thecæ or asci exposed, as in discomycetous fungi and gymnocarpous lichens; discomyce- to us; gymnocarpous. ectotriceps (ek-tot'ri-seps), (ek-tot'r n.; pl. ectotricepites (ek-tot-ri-sep'i-tēz). [NL., Gr. ἐκτός, out- side, + NL. triceps .] In an at ., the outer head or external division of the triceps muscle of the arm, considered as a distinct muscle. Also ex- tratriceps. IMG:content-0206.png:[blocks in formation] ectosarcodous (ek-tō-särkō-dus), a. [ ecto- sarcode + -ous.] Consisting of external sar- code; constituting an ectosare; ectoplasmic. ectosarcous (ek-to-särkus), a . [ ectosome + -al .] Ectopistes (ek-to-pis'tēz), n. [NL., έκτο- πίζειν, wander, migrate, έκτοπος , away from a place, ἐκ + τόπος , place.] A genus of pigeons, of the family Columbida . They have short tarsi feathered part way down in front, a short bill feathered Of or pertaining to the ectosome; cortical, as far forward, the wings acutely pointed by the first three The Century Dictionary and Cyclopedia: Dictionary ectropical ectropical (ek-trop'i-kal), a. [