mesoderm


mesoderm
The middle of the three primary germ layers of the embryo (the others being ectoderm and endoderm); m. is the origin of connective tissues, myoblasts, blood, the cardiovascular and lymphatic systems, most of the urogenital system, and the lining of the pericardial, pleural, and peritoneal cavities. SYN: mesoblast. [meso- + G. derma, skin]
- branchial m. m. surrounding the primitive stomodeum and pharynx; it contributes to the pharyngeal arches.
- extraembryonic m. extraembryonic cells which, though derived from the zygote, are not part of the embryo proper and contribute to the fetal membranes ( e.g., amnion). SYN: primary m..
- gastral m. m. in lower vertebrates formed by constriction from the roof of the archenteron or yolk sac.
- intermediate m. a continuous band of m. between the segmented paraxial m. medially and the lateral plate m. laterally; from it develops the nephrogenic cord.
- intraembryonic m. m. derived from the primitive streak and lying between the ectoderm and endoderm. SYN: secondary m..
- lateral m. SYN: lateral plate m..
- lateral plate m. the peripheral portion of intraembryonic m. that is continuous with the extraembryonic m. beyond the margins of the embryonic disk; it forms the somatic and splanchnic m. between which develops the intraembryonic celom. SYN: lateral m..
- paraxial m. the m. lying at either side of the midline embryonic notochord; on segmentation, it forms the paired somites.
- primary m. SYN: extraembryonic m..
- prostomial m. m. that arises in lower vertebrates by continued proliferation at the lateral lips of the blastopore.
- secondary m. SYN: intraembryonic m..
- somatic m. the m. adjacent to the ectoderm in the early embryo, after formation of the intraembryonic celom; the limbs and body wall are derived, in part, from it.
- somitic m. m. derived from cells situated in or derived from somites.
- splanchnic m. the layer of lateral plate m. adjacent to the endoderm.
- visceral m. the splanchnic m. or the branchial m..

* * *

me·so·derm 'mez-ə-.dərm, 'mēz-, 'mēs-, 'mes- n the middle of the three primary germ layers of an embryo that is the source esp. of bone, muscle, connective tissue, and dermis broadly tissue derived from this germ layer
me·so·der·mal .mez-ə-'dər-məl, .mēz-, .mēs-, .mes- also me·so·der·mic -'dər-mik adj
me·so·der·mal·ly adv

* * *

n.
the middle germ layer of the early embryo. It gives rise to cartilage, muscle, bone, blood, kidneys, gonads and their ducts, and connective tissue. It separates into two layers - an outer somatic and an inner splanchnic mesoderm, separated by a cavity (coelom) that becomes the body cavity. The dorsal somatic mesoderm becomes segmented into a number of somite. See also mesenchyme.
mesodermal adj.

* * *

meso·derm (mezґo-) (meґzo-dərm″) [meso- + -derm] the middle layer of the three primary germ layers of the embryo, lying between the ectoderm and the endoderm. From it are derived the connective tissue, bone and cartilage, muscle, blood and blood vessels, lymphatics and lymphoid organs, notochord, pleura, pericardium, peritoneum, kidney, and gonads. Cf. ectoderm and endoderm. mesodermal, mesodermic adj

Medical dictionary. 2011.

Look at other dictionaries:

  • Mesoderm — Tissues derived from mesoderm …   Wikipedia

  • Mesoderm — Mesoderm, in der Embryonalentwicklung höherer Tiere (⇒ Bilateria) bei der ⇒ Keimblätterbildung entstehendes drittes Keimblatt, das sich zwischen Ektoderm und Entoderm schiebt. Man unterscheidet verschiedene Entstehungswege: a) Abfaltung… …   Deutsch wörterbuch der biologie

  • mesoderm — (n.) 1858, from Fr. mésoderme or Ger. Mesoderm, lit. middle skin, coined by German physician Robert Remak (1815 1865) from MESO (Cf. meso ) + Gk. derma (see DERM (Cf. derm)) …   Etymology dictionary

  • Mesoderm — Mes o*derm, n. [Meso + Gr. de rma skin.] (Biol.) (a) The layer of the blastoderm, between the ectoderm and endoderm; mesoblast. See Illust. of {Blastoderm} and {Ectoderm}. (b) The middle body layer in some invertebrates. (c) The middle layer of… …   The Collaborative International Dictionary of English

  • Mesodérm — Mesodérm, s. Keimblätter und Entwickelungsgeschichte, S. 845 …   Meyers Großes Konversations-Lexikon

  • Mesodérm — (grch.), s. Gastrula …   Kleines Konversations-Lexikon

  • mesoderm — [mes′ə dʉrm΄, mez′ə dʉrm΄] n. [ MESO + DERM] the middle layer of cells of an embryo, from which the skeletal, reproductive, muscular, vascular, connective, etc. tissues develop mesodermal adj. mesodermic …   English World dictionary

  • Mesoderm — Das Mesoderm ist das mittlere Keimblatt des Embryoblasten. Die Mesoderm Zellen entstehen beim Menschen in der dritten Entwicklungswoche durch Einwanderung zwischen Epiblast und Hypoblast (Schizocoelie). Der Begriff Mesoderm ist nicht… …   Deutsch Wikipedia

  • Mesoderm — Me|so|dẹrm 〈n. 11; Biol.〉 das mittlere Keimblatt des sich entwickelnden Embryos [<grch. mesos „mittel “ + derma „Haut“] * * * Me|so|dẹrm, das; s, e [zu griech. dérma = Haut] (Biol., Med.): (während der Embryonalphase) bei vielzelligen Tieren …   Universal-Lexikon

  • mesoderm — n. the middle germ layer of the early embryo. It gives rise to cartilage, muscle, bone, blood, kidneys, gonads and their ducts, and connective tissue. It separates into two layers – an outer somatic and an inner splanchnic mesoderm, separated by… …   The new mediacal dictionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.