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PubMed1978

Identification and distribution of gap junctions in the mesoderm of the developing chick limb bud.

Sub-ridge, core, anterior and posterior borders of mesoderm were dissected from stages 22-24 chick wing buds to investigate whether structures for intercellular coupling develop between mesenchymal cells. Fine structure was examined using techniques of transmission electron microscopy, freeze-fracture and scanning electron microscopy. Gap (communicating) junctions which were observed between mesenchymal cells of all limb bud regions were distributed between apposed cell bodies, points of contact between cell processes and other cell bodies, and between contacting tips of slender cell projections. In addition particularly in the the subridge region, filopodia were observed to extend through the intercellular matrix to contact other cells several micrometers distant. The observations reported in this paper show that mesodermal cells throughout the limb have the structural capability for electrotonic and metabolic coupling during a critical period of morphogenesis in the avian limb. Whether intercellular signals which are thought to be transmitted through gap junctions are active in normal limb development remains to be investigated.

Animals↗
PubMed1978

Mesodermalization of amphibian gastrula ectoderm in transfilter experiments.

Transfilter experiments were carried out with competent gastrula ectoderm of Triturus vulgaris and Ambystoma mexicanum as the reacting materials and blastoporal lip, alcohol-treated bone marrow and archenteron roof as the inducing materials, It was shown that a mesodermal inducing substance is able to penetrate Nuclepore filters of different pore sizes (3.0, 1.0, 0.4, 0.2 micrometer). The degree of mesodermal differentiations depends on the reacting materials, the inductors and the filters which were used in the transfilter experiments.

Ambystoma↗
PubMed1978

Benign and low grade variants of mixed mesodermal tumor (adenosarcoma) of the ovary and adnexal region.

Eleven examples of a rare group of neoplasms composed of both epithelial and mesenchymal components are reported. Ten arose from the ovary and one arose separately in the para-ovarian region. The neoplasms are distinctive in that the stoma is more cellular than that of adenofibromas, but epithelial component is not malignant, as in carcinosarcoma and mixed mesodermal tumors, and the stoma is not sarcomatous in the low grade varieties. The 11 cases were highly variable in the cellularity and atypism of the stromal cells. The term, adenosarcoma, for these tumors is not acceptable because some were too low a grade to be regarded as sarcomas, and reports of the uterine counterpart disclose that some contain heterologous elements. For that reason, a term that will embrace the full spectrum of changes in the stroma--benign through sarcomatous--is needed. We propose that they be regarded as variants of mixed mesodermal tumor so that both the benign neoplasms and low grade sarcomas can be accommodated under one designation. Of the 11 cases, five lowest grade examples were all confined to the ovary and did not recur after surgical excision, but some of these were borderline in malignancy and probably would have progressed if untreated. Two of the 3 intermediate grade neoplasms extended beyond the ovary but were arrested by surgical excision. The 3 highest grade neoplasms were overly sarcomatous. One of these extended beyond the ovary but was arrested by combination chemotherapy. The para-ovarian adenosarcoma (also high grade) metastasized and proved fatal.

Adenofibroma↗
PubMed1978

Mixed mesodermal tumor and clear cell carcinoma arising in ovarian endometriosis.

A case is reported of clear cell carcinoma, arising as several papillary masses from the lining of an endometrial cyst within the ovary, associated with a mixed mesodermal tumor arising in the stalk of the largest papillary nodule. The origin of this tumor from within a focus of endometriosis lends support to the theory that both the epithelial and mesodermal components are of Müllerian (Paramesonephric) origin.

Adenocarcinoma↗
PubMed1977

A diffusion model for mesoderm induction in amphibian embryos.

In this paper we try to answer the question whether diffusion is a possible mechanism to explain mesoderm induction in Amphibians. First the embryological data are discussed and a hypothesis for mesoderm formation is set forth. The blastula being essentially a hollow sphere, we assume that the induction mechanism in an embryo at the blastula stage can be simulated by diffusion-reaction processes on spherical surfaces. A model is constructed for the simple case when the source is held constant with respect to time, the decay proportional to the concentration and the diffusion coefficient a constant. From simulation we find a (best) value for the decay constant to be 6 x 10(-5)/sec and for the diffusion constant to be 0.24 x 10(-6) cm2/sec. The relation between the parameters is derived from an analytic solution for the diffusion process on a spherical surface with a continuously producing point source and the concentration proportional to the decay. The form and regulative properties of the steady concentration gradient are discussed.

Amphibians↗
PubMed1978

The lack of an inhibitory effect of hyaluronate on chondrogenesis in chick limb-bud mesoderm cells grown in culture.

The effect of hyaluronate on chondrogenesis in cultures of chick limb-bud mesoderm cells, derived from stage 20--21, 23--24 and 26 embryos grown at different cell densities and in 3 different culture media, was studied. The results show that hyaluronate at a concentration of 500 microgram/ml, does not consistently produce an inhibition of chondrogenesis in cultures of stage 20--21, 23--24 or 26 limb-bud mesoderm cells in contrast to what has been reported by Toole et al. (1972). It was demonstrated that under optimal conditions, stage 26 cells grown in the absence of hyaluronate do not form as many cartilage colonies in culture as do cells from stage 20--21 or 23--24 embryos. It was determined that culture medium composed of Eagle's MEM supplemented with 7% horse serum, 3% fetal calf serum and 5% 10-day chick embryo extract supported chondrogenesis significantly better than Ham's F-12 supplemented with 10% fetal calf serum. Our results suggest that the inhibition of chondrogenesis by hyaluronate reported earlier is most likely due to the sub-optimal conditions of growth medium, cell density and embryonic stage than to the hyaluronate treatment.

Animals↗
PubMed1978

Extrauterine mesodermal (müllerian) adenosarcoma: a clinicopathologic analysis of five cases.

Five extrauterine examples (three pelvic and two ovarian) of a distinctive mesodermal (müllerian) mixed tumor previously described to occur in the uterus and designated müllerian adenosarcoma are reported. The tumors were diagnosed during the fifth to eight decades of life. They usually formed very large, partly cystic masses, which had occasionally spread to adjacent organs by the time of operation. On microscopic examination the tumors consisted of benign-appearing neoplastic glands lying in a sarcomatous stroma. The glands were lined by a variety of müllerian epithelial cell types, and the stromal element resembled endometrial stromal sarcoma. Three patients had malignant courses manifested by intrabdominal recurrence, distant metastases, or both. This tumor should be clearly distinguished from the more common forms of mesodermal (müllerian) mixed tumor in which the epithilial as well as the stromal component is malignant and the prognosis is much more grave.

Adult↗
PubMed1979

Ultrastructure of mesodermal mixed tumor of the uterus.

A case of mesodermal mixed tumor arising in the uterus of a 57-year-old woman is presented. The tumor was a mixture of adenocarcinoma with occasional squamous metaplasia, stromal sarcoma, myxosarcoma and chondrosarcoma. Light and electron microscopic examinations of the tumor revealed close transition between stromal sarcomatous component and each of other sarcomatous and carcinomatous component. The histogenesis of mixed mesodermal tumor was discussed and it was concluded that the tumor might be derived from endometrial stromal cell which possessed the pluripotency to differentiate toward various epithelial and mesenchymal tissues including the heterologous mesenchymal tissue.

Adenocarcinoma↗
PubMed1979

Stimulation of corneal wound healing with mesodermal growth factor.

Mesodermal growth factor (MGF) from mouse submaxillary glands was tested in vivo for stimulating effects on corneal wounds in rabbits. Intrastromal injection of 5 microgram of MGF induced widespread fibroblast activity and stromal cell division, and markedly stimulated stromal healing. At high doses (greater than 25 microgram), corneal destruction was indicated by extensive necrosis and perforation. When low doses (1 to 5 microgram) of MGF were applied to the lip of nonperforating knife wounds of the cornea, three major differences were noted between control and experimental wounds. In wounds treated with MGF, the depth of stromal healing was greater, as was the intensity of the fibroblast activity, and the width and depth of the epithelial plug were significantly decreased. These results establish that MGF is an effective growth-stimulating agent in vivo and that the initial stages of corneal wound healing may be accelerated in vivo.

Animals↗
PubMed1979

Differentiating abilities of avian somatopleural mesoderm.

Quail-to-chick grafting experiments were performed on 2-day embryos in order to test the differentiating abilities of the somatopleure. After orthotopic and heterotopic transplatations of different parts of quail somatopleural mesoderm into chick embryos it is demonstrated that avian somatopleural cells differentiate into skeletal elements, smooth muscles, tendons and connective tissues. However, skeletal muscle fibres do not originate from somatopleural cells.

Animals↗
PubMed1977

Immunological and biochemical studies of collagen type transition during in vitro chrondrogenesis of chick limb mesodermal cells.

This work describes an approach to monitor chondrogenesis of stage-24 chick limb mesodermal cells in vitro by analyzing the onset of type II collagen synthesis with carboxymethyl-cellulose chromatography, immunofluorescence, and radioimmunoassay. This procedure allowed specific and quantitative determination of chondrocytes in the presence of fibroblasts and myoblasts, both of which synthesize type I collagen. Chondrogenesis was studied in high-density cell preparations on tissue culture plastic dishes and on agar base. It was found that stage-24 limb mesenchymal cells initially synthesized only type I collagen. With the onset of chondrogenesis, a gradual transition to type II collagen synthesis was observed. In cell aggregates formed over agar, type II collagen synthesis started after 1 day in culture and reached levels of 80-90 percent of the total collagen synthesis at 6-8 days. At that time, the cells in the center of the aggregates had acquired the typical chondrocyte phenotype and stained only with type II collagen antibodies, whereas the peripheral cells had developed into a "perichondrium" and stained with type I and type II collagen antibodies. On plastic dishes plated with 5 X 10(6) cells per 35mm dish, cartilage nodules developed after 4-6 days, but the type II collagen synthesis only reached levels of 10-20 percent of the total collagen. The majority of the cells differentiated into fibroblasts and myoblasts and synthesized type I collagen. These studies demonstrate that analysis of cell specific types of collagen provides a useful method for detailing the specific events in the differentiation of mesenchymal cells in vitro.

Animals↗
PubMed1975

Nicotinamide adenine dinucleotide levels in chick limb mesodermal cells in vitro: effects of 3-acetylpyridine and nicotinamide.

The studies reported here show that in cultures of developing mesodermal cells, chondrogenic expression is associated with a progressive decline in cellular NAD+ levels. Furthermore, reduced cellular NAD+ levels resulting from exposure to the nicotinamide analog 3-acetylpyridine are correlated with a 2- to 100-fold potentiation of chondrogenic expression. Conversely, elevated NAD+ levels resulting from exposure to nicotinamide alone are correlated with inhibition of chondrogenic expression. These data are consistent with the hypothesis that pyridine nucleotides, or some derivative thereof, play a central role in the control of muscle and cartilage development in embryonic chick limbs.

Animals↗
PubMed1977

[Induction of the mesoderm and primordial germ cells by the endoderm of Pleurodeles waltlii (Amphibia, Urodele): development during gastrulation].

Blastulae ectoderm is combined with dorsal or ventral endoderm from blastulae, gastrulae and early neurulae. In vitro culture reveals the presence of different mesodermal structures whose nature is connected with the endoderm origin site. Primordial germ cells differentiate essentially in the recombinates including ventral endoderm. The inducing capacity of this latter concerning germ cells is maximum at the beginning of gastrulation, then decreases during it and finally disappears at the onset of neurulation.

Age Factors↗
PubMed1978

[Differentiation of the endodermal epithelium associated with the splanchnic mesoderm].

Allantoic epithelium and epithelium from different levels of the digestive tube of the guail embryo were grafted into chick embryo splanchnopleure so that these epitheliums would come into contact with the mesoderm of the developing host digestive tube at a variety of levels. Under these conditions, the allantoic epithelium develops into an epithelium corresponding to the level of the digestive tube at which it was grafted. By contrast, the presumptive fate of epithelium from the small intestine is not modified by the mesenchyme with which it becomes associated. Mesenchyme from the small intestine, on the other hand, always dictates the type of differentiation in epithelial grafts from other levels of the digestive tube.

Allantois↗
PubMed1979

Activation of initial wound healing responses in rat corneas in organ culture by mesodermal growth factor.

In organ culture, mesodermal growth factor (MGF) from mouse submaxillary glands stimulates fibroblast formation, mitosis, and migration of cells into the dead-cell zone adjacent to the wound edge of rat corneal buttons. A classic dose-response relationship between the width of the stromal fibroblast zone and the dose of MGF suggests that fibroblast zone width may be used as a measure for screening agents which influence the initial stages of corneal wound healing.

Animals↗
PubMed1978

Regional differences in the morphology and motility of mesodermal cells from the early wing-bud of normal and talpid3 mutant chick embryos.

A method of culturing has been employed to compare the properties of cells migrating from small mesodermal explants taken from different regions of normal and mutant limb-buds at different stages of development. An analysis by time-lapse cinematography of the morphology and mobility of cells migrating from explants defines a distal region within the limb-bud where these properties are distinct from those of cells from more proximal regions. In the normal wing-bud distal cells subjacent to the apical ectodermal ridge possess a characteristic multipolar morphology and translocate slowly in vitro. Cells from more proximal regions tend to be bipolar and translocate more rapidly. Distal and proximal cells also probably differ in their adhesive strengths. In the mutant, talpid3, distal and proximal cells do not differ in the above properties and cells from all regions of the limb-bud are multipolar, translocate slowly and are more adhesive than normal cells. A study of light micrographs and scanning electron micrographs suggests that these regional differences are found in the limb-bud in vivo and are not merely an effect produced by the in vitro culturing system.

Animals↗