Mesenchyme


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Related to Mesenchyme: Metanephric mesenchyme

mesenchyme

[′mez·ən‚kīm]
(embryology)
That part of the mesoderm from which all connective tissues, blood vessels, blood, lymphatic system proper, and the heart are derived.

Mesenchyme

 

the embryonic connective tissue in the majority of multicellular animals and man.

In the early stages of embryonic development, mesenchyme consists of motile dendriform cells. Most of these cells later lose their motility and unite by their processes into a network (syncytium) or form local aggregates. The mesenchyme originates from cells that have migrated from various germ layers. For example, the chief source of the mesenchyme in coelenterates, worms, and mollusks is the ectoderm (often also the endoderm), and in chordates and echinoderms, the mesoderm. Mesenchyme that originates from endoderm and mesoderm is called endomesenchyme, and mesenchyme originating from ectoderm (the material of the neural columns), ectomesenchyme. In vertebrates and man, endomesenchyme gives rise to various forms of connective tissue in the adult, formed elements of the blood, blood vessels, and smooth muscles. Almost the entire visceral skeleton (the auditory ossicles, gill arches), the pigment cells, and part of the derma are formed from ectomesenchyme.

The poorly differentiated connective-tissue cells (fibroblasts and reticular cells) found in animals and man during the postembryonic period are sometimes called mesenchyme.

REFERENCE

Tokin, B. P. Obshchaia embriologiia, 2nd ed. Leningrad, 1970.

T. A. DETLAF

References in periodicals archive ?
By CS14, the number of mesenchymal cells has increased in the septal and parietal OFT cushion, and a-SMA-positive cells have accumulated and formed columns of condensed mesenchyme throughout the cushion [Figure 3]f, [Figure 3]g, [Figure 3]h.
Ectodysplasin (Eda) is expressed in mesenchyme and its receptor Ectodysplasin-A receptor (Edar) is expressed in the epithelium.
Although in the dorsal region of the first cleft, Hey1 expression expanded toward the mesenchyme. The signal was also evident in the maxillary and mandibular prominences, although with lower intensity in the latter, in contrast to the signal observed in the ventral region of BA2 and BA3; furthermore, this signal extended from the second cleft toward the adjacent mesenchyme, invading the caudal-most region of BA2.
In the real-time RT-PCR study, specific primers (Vps26A-F: 5'-TTTTTGGTCCCATTTGTGAGA-3' and Vps26A-R: 5'-GCCTCTTTCCAGGTTGCTT-3') were used to amplify a 168bp fragment with the cDNA from reserve mesenchyme of different growth periods.
(b) The numbers of TRAP-positive cells in the suture mesenchyme of calvaria from the mouse groups administered with PBS, LPS, LPS with exendin-4, and exendin-4, respectively.
It has been shown that hepatoblasts and septum transversum mesenchyme express various matrix metalloproteinases (MMPs) on the embryonic 9.5th day in mice.
Investigation of Tumor Invasion into Chorionic Epithelium and Mesenchyme. Serial histological sections of the experimental tumors and CAM were performed to evaluate tumor invasion.
In Group II was observed an increased amount of the number and caliber of the bronchi and bronchioles (Figures 2D and 2E), decreased mesenchyme and the initial opening of the internal lumen of the bronchioles (Figure 2F).
Cook (1999) had proposed that metaplasia of mesenchyme of mostly neural ectoderm, resulting in abnormal differentiation of surface ectoderm, as the most likely mechanism of occurrence of dermoid.
Tobinet al.8 reported that hair mesenchyme possessessignificant hair cycle-related modulation.
As the jaw develops, the ectoderm guides patterning into the mesenchyme (3) involving an antagonistic action between a signal of bone morphogenic proteins (BMP-4) and fibroblast growth factor-8 (FGF8) (3,4).
Since malignant tumors that originate in the mesenchyme are very rare, the differential diagnosis is difficult.