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At least 19 recordsLinked to original sources

PubMed1992

[Study on the peritoneal stomata and absorptive mechanism of ascites].

The peritoneal stomata in sixteen human specimens were studied by SEM, TEM and ODO freeze fracture techniques. In order to prove that the peritoneal stomata are the passage ways by which ascites is absorbed from the peritoneal cavity, animal experiments were performed. The results showed that the peritoneal stomata, which were only found between the cuboidal cells, were formed by the cytoplasmic processes of nearby cells. There were no basement membranes in the peritoneal stomata or the cuboidal cells which formed the peritoneal stomata. Microfilaments were observed in the cuboidal cells. Cytoplasmic processes of mesothelial cells and networks of connective tissue were found in the peritoneal channels. These had networks which formed the floor of each stomata and the roof of each lacunae. We observed that numbers and diameters of the peritoneal stomata were increased in mice with ascites. Red cells and carbonic particles injected into the peritoneal cavity were absorbed by the peritoneal stomata. So the microfilaments of the cuboidal cells, the cytoplasmic processes, and the fiber networks in the peritoneal channels can adjust the absorptive properties of the peritoneal stomata. The peritoneal stomata are an important pathway for draining ascites from the peritoneal cavity.

Absorption↗

PubMed1991

Development of immature stomata: evidence for epigenetic selection of a spacing pattern.

In Sansevieria trifasciata as many as half the potential stomata remain immature. The development of all stomatal structures started at the same time and the early stages of the development of immature stomata had no special characteristics. Statistical analysis showed that the mature stomata were more evenly spaced than all potential stomata, both mature and immature. Furthermore, the distribution of mature stomata per unit area was more predictable or orderly than comparable structures of a random model that developed in the same way. These facts indicate that a nonrandom loss of many stomata by "immaturity" is a major determinant, acting during rather than preceding development, of the distribution of the mature, functional stomata. Thus in Sansevieria there is a selection of an epidermal pattern from an excess of cells that undergo the early stages of stomatal development.

Cell Differentiation↗

PubMed1991

Study on the ultrastructure of the peritoneal stomata in humans.

In 16 human specimens the topography and organization of stomata and mesothelial cells of the diaphragmatic, pelvic wall and anterior abdominal wall peritoneum were studied by transmission electron microscopy, scanning electron microscopy and the image processing technique. The mesothelial cells were organized into two discrete populations, cuboidal cells and flattened cells. The stomata were found only among cuboidal cells, either on the muscular portion or on the tendinous portion of the diaphragm. The size and shape of stomata, which were arranged in a cluster or a strip, were often irregular. The average area of a stoma on the muscular portion was 10.43 +/- 1.61 microns2, on the tendinous portion 7.93 +/- 1.67 microns2. Stomata opened to submesothelial connective tissue, under which numerous lymphatics were observed. Stomata were not discovered in the pelvic and anterior abdominal wall peritoneum. In animal experiments intraperitoneally injected trypan blue particles were rapidly removed from the peritoneal cavity through stomata of the diaphragmatic peritoneum in rabbits. It is suggested that stomata may be the main pathway for draining matter from the peritoneal cavity and that the diaphragmatic peritoneum shows the strongest absorption in all parts of the peritoneum.

Abdominal Muscles↗

PubMed1985

The presence of lymphatic stomata in the ovarian bursa of the golden hamster.

The histology and function of the lymphatic system in the ovarian bursa of the golden hamster were examined at each day of the estrous cycle. The lymphatic passage from the ovarian bursa to a para-aortic lymph node was stained black by india ink injected into the bursal cavity. This suggests that bursal fluid drains from the cavity via lymphatic vessels. Lymphatic stomata connecting the bursal cavity with the lymphatic lumen were consistently present throughout the cycle. However, the stomata were more frequently observed in the bursae on day 1 than on day 4 of the cycle. Also, they were more frequently observed in the bursa injected with 5 microliters of chick erythrocytes than in the contralateral (not injected) bursa in hamsters on day 4 of the cycle. These results suggest that the stomata are openings the patency of which varies in response to changes in the bursal cavity. There were regions where the lymphatic lumen was separated from the bursal cavity only by lymphatic endothelial cells. These regions were present throughout the estrous cycle. They may be patent stomata; dehiscence of junctions between the endothelial cells may give rise to stomata or widen the stomata orifices that are already present.

Animals↗

PubMed1985

The significance of endothelial stomata and stigmata in the rat aorta. An electron microscopic study.

Perfusion of arteries with dilute silver nitrate produces in the endothelium (a) a pattern of pericellular black lines, which we earlier interpreted as a marker of the physiological electrolyte pathway (Zand et al. 1982), and (b) focal black deposits on or between the cells, either ring-shaped (stomata) or solid (stigmata). The purpose of this study was to clarify the nature and significance of these controversial structures. A glutaraldehyde-fixed normal rat aorta was perfused with silver nitrate; 17 typical stomata and stigmata were photographed en face, then studied on ultrathin serial sections. When seen en face, they fell into three groups: (I) 4 stomata in endothelial cells; (II) 6 stigmata in endothelial cells; (III) 7 stigmata on intercellular junctions. By electron microscopy, (I) all the stomata in endothelial cells corresponded to myoendothelial herniae. (II) Of the 6 stigmata in endothelial cells, 4 corresponded again to myoendothelial herniae, 2 corresponded to blebs (it seemed likely that these blebs had existed in vivo, but the possibility of a fixation artefact could not be excluded). (III) Of the 7 stigmata on intercellular junctions, one corresponded to the diapedesis of a mononuclear cell; the other 6 did not correspond to visible endothelial changes and are best interpreted as points of normally higher permeability. We conclude that stomata and stigmata (under the conditions of our experiments) can be explained in at least 4 different ways, depending in part on their location (in cells, on junctions). These ancient terms therefore remain useful for descriptive purposes, as long as it is realized that their significance in any given case must be determined by electron microscopic study.

Animals↗

PubMed1989

On the presence and function of closed lymphatic stomata in the diaphragm of the golden hamster.

The peritoneal surface of the golden hamster diaphragm was examined for closed lymphatic stomata by scanning electron microscopy (SEM) and serial sectioning. Closed stomata were absent on SEM but present on serial sectioning. Some closed stomata in the serial sections were reconstructed using a computerized image analysis system. They were less than 10 microns in diameter and consisted of an outer mesothelial margin and an inner lymphatic wall. The lymphatic wall was formed by several endothelial cells adjoined with various junctional abutments. The discrepancy of results between SEM and serial sectioning, and the functional aspects of lymphatic stomata are discussed.

Animals↗

PubMed1990

The distribution of lymphatic stomata in the diaphragm of the golden hamster.

Golden hamster diaphragms were observed with both light and electron microscopes to examine the distribution of lymphatic stomata and their morphological features. Lymphatic stomata were present on the inferior surface but absent on the superior surface. This observation was also supported by the results of India ink injection into the peritoneal and pleural cavities. On the inferior surface of the diaphragm, lymphatic stomata tended to form radial rows running from the centre to the periphery; i.e. they were found throughout the muscular and tendinous portions, although the density of their distribution was higher in the latter. Lymphatics and lymphatic lacunae in the tendinous portion were generally smaller than those in the muscular portion. Lymphatic flow into the lymphatics of the tendinous portion seems to be slow, suggesting that lymphatic stomata in the portion may be a functionally inactive reserve.

Animals↗

PubMed2026

Co-option of stomata in the convergent evolution of fern nectaries.

Understanding the origin of new structures is a central goal of evolutionary biology. In many instances, novel phenotypes arise through heterotopy: the expression of a structure in a new location. Using bracken fern (Pteridium aquilinum) as a model, we combine genomics, transcriptomics and metabolomics to begin to explore the origin and developmental routes in the convergent evolution of ant-enticing nectaries. We observe that P. aquilinum does not exclusively express flowering plant 'nectary genes' during nectary development. Rather, this fern builds nectaries through co-option of stomata. Specifically, P. aquilinum heterotopically expresses canonical angiosperm stomatal regulatory genes, leading to stomatal development in novel positions along the petiole. These non-laminar stomata were co-opted for nectar secretion through the expression of putative sugar transport genes, forming secretory nectarostomata. This work provides two advances in our understanding of nectary evolution and the origin of complex structures. First, heterotopic expression of stomata, and later exaptation, represents one realized developmental mechanism for the evolution of nectar glands. Second, while there are many routes to nectary evolution, nectarostomata development is a repeatable path that has evolved in ferns and flowering plants, representing an impressive case of convergent evolution through the same developmental mechanism, despite over 400 million years of divergent history.

Plant Stomata↗

PubMed1991

Distribution of diaphragmatic lymphatic stomata.

In seven anesthetized rabbits we measured the size, shape, and density of lymphatic stomata on the peritoneal and pleural sides of the diaphragm. The diaphragm was fixed in situ and processed for scanning electron microscopy. Results are from 2,902 peritoneal and 3,086 pleural fields (each 1,620 microns 2) randomly chosen from the various specimens. Stomata were seen in 9% of the fields examined, and in 30% of the cases they appeared grouped in clusters with 2-14 stomata/field. Stoma density was 250 +/- 242 and 72 +/- 57 (SD) stomata/mm2 on peritoneal and pleural sides, respectively, and it was similar over the muscular and tendinous portion of the two surfaces. The maximum diameter ranged from less than 1 to approximately 30 microns, with an average value of 1.2 +/- 3.1 micron. The ratio of the maximum to the minimum diameter and the surface area averaged 2 +/- 1.4 and 0.7 +/- 2.4 micron 2, respectively. The maximum and minimum diameter and surface area values followed a lognormal frequency distribution, suggesting that stomata geometry is affected by diaphragmatic tension.

Animals↗

PubMed1979

Mesothelial stomata overlying omental milky spots: scanning electron microscopic study.

The presence in the rat omentum of intercellular pores (the classical stomata of von Recklinghausen) between the mesothelial cells overlying aggregates of lymphoreticular cells (the classical milky spots of Ranvier) and the apparent migration of lymphocytes through these stomata were recorded for the first time by scanning electron microscopy. Previous studies on passage of cells across the peritoneum and omentum used experimentally administered cells, while in the present study no cells were administered to the rats and their own lymphocytes were observed in situ. The possible role of lymphocytes in the peritoneal cavity is also briefly discussed.

Animals↗

PubMed2025

Smarter stomata: emergent technologies unlocking yield potential in a changing climate.

Stomata, the gatekeepers of leaf gas exchange, regulate carbon dioxide uptake and water loss, functions increasingly critical as crops face more frequent, intense heat and drought. Under dry conditions, stomatal conductance (g s) typically decreases, limiting carbon assimilation and yield. Heat stress, in contrast, elicits variable g S responses: sometimes increasing to facilitate transpirational cooling, while at other times decreasing, especially when combined with drought. Heat and drought also induce complex, context-dependent shifts in stomatal anatomy. Smaller, denser stomata improve drought resilience in some cases, while reduced density confers greater tolerance in others. The optimal stomatal ideotype remains unknown, and different or even opposing traits may confer resilience dependent on the environmental scenario. Substantial genotypic variation in g s and stomatal anatomy, high heritability and co-localized quantitative trait loci for stomatal traits and yield highlight their untapped potential as breeding targets for climate-resilient crops. However, stomatal traits remain largely absent from breeding pipelines due to challenges of phenotyping at scale. This is changing rapidly. Advances in deep learning, porometry, digital microscopy, and remote sensing now enable high-throughput measurement of stomatal physiology and anatomy. Next-generation breeding technologies including clustered regularly interspaced short palindromic repeats (CRISPR), multi-omics approaches, and artificial intelligence-driven ideotype selection models could revolutionize breeding, allowing precise engineering of stomatal traits for resilience to environmental stress. The time has come to move beyond characterizing stomatal traits and start actively incorporating them into breeding strategies. By leveraging these technologies, stomatal traits can become high value targets, unlocking their potential to enhance crop performance in a hotter, drier future.

abiotic stress↗

PubMed1979

On the differential divisions and preprophase microtubule bands involved in the development of stomata of Vigna sinensis L.

The manifestation of premitotic cell polarity and the resultant structural asymmetry of the differential divisions participating in the development of stomata of Vigna sinensis vary considerably. However, two morphologically distinct types of differential division were distinguished: (a) 'asymmetrical differential divisions', in which the premitotic polarization of the cell, the eccentric position of the nucleus during division and the differences in size and organization of the daughter cells are obvious; and (b) differential divisions in which the above features are inconspicuous or almost absent. The former occur in the ordinary protodermal cells, the latter in some meristemoids. The organization of a sharply demarcated preprophase microtubule band (PMB) precedes, all differential and non-differential divisions. In the first type of differential division the PMB is formed eccentrically, while in the second it may display either an approximately symmetrical or a clearly asymmetrical disposition, always indicating with surprising accuracy the sites where the succeeding cell plate will join the parent walls. The PMB foreshadowing the highly curved cell plates in meristemoids I of the mesoperigenous process, as well as in meristemoids I and II of the mesogenous one, are apposed only on one anticlinal wall and therefore do not encircle the nucleus or traverse the cell. In the symmetrical divisions of guard cell mother cells (GMC), as well as in those of protodermal cells, the PMB runs right round the internal plasmalemma surface in an equatorial position, coinciding with that of the future cell plate. In the former cells the wall abutting the cortical cytoplasm traversed by the band becomes locally thickened. The variability in the pattern of the microtubules of the band along the walls of the GMC is directly mirrored in the pattern of the thickening. It seems that in GMC the PMB mediates a directed exocytosis of dictyosome vesicles. In contrast to what is now generally accepted in dicotyledonous plants, each meristemoid I of both the mesogenous and mesoperigenous stomata in Vigna sinensis leaves does not inhibit but induces the formation of other meristemoids close to it.

Cell Differentiation↗

PubMed1987

Postnatal development of the ovarian bursa of the golden hamster (Mesocricetus auratus): its complete closure and morphogenesis of lymphatic stomata.

The golden hamster ovarian bursa was studied by light and electron microscopy to clarify the process of its complete closure and the development of lymphatics that leads to morphogenesis of stomata. The results were as follows. 1) The bursa completely closed at 9 days of age primarily due to development of the mesotubarium superius. 2) With the closure, the ovary and bursa became closely apposed, and most of the original bursal cavity disappeared. 3) Between 9 and 12 days of age U-shaped folds of the bursal mesothelium began to invade the connective tissue of the bursa. 4) Widening of the internal angle of the U-shaped folds contributed to reappearance of the bursal cavity, and thus separation of the bursa from the ovary. It also contributed to future geometrical proximity of lymphatics to the cavity of the bursa. 5) The separation of the bursa from the ovary began as early as 12 days of age in the cephalic half of the bursa. It occurred remarkably late in the caudal half. Juxtaposition of the window portion of the bursa to the ovary remained in some adult animals. 6) Development of lymphatics in the cephalic half of the bursa was divided into two stages, before and after days 21-24 of life. In the first stage, lymphatics grew in the submesothelial connective tissue, and the framework of lymphatics was formed. In the second stage, lymphatics extended small branches to form the submesothelial plexus or lymphatic lacuna. 7) Intercellular junctions between contiguous lymphatic endothelial cells were mostly tight and desmosomelike. Open junctions were, if they occurred at all, rare. (8) A smooth-surfaced area lined with the lymphatic endothelium was found in the bursa on day 27 of life, before the initiation of ovulation. Valvelike stomal orifices were absent before the initiation of ovulation and extremely rare even after the first ovulation. They were commonly present in the bursae after the fourth ovulation, however. The process of complete closure of the ovarian bursa is very complex and may be related to the later development of the bursal mesothelium and lymphatics. Some liplike stomal orifices are of purely developmental origin. However, all valvelike stomal orifices are assumed to be formed as a result of damage to the bursal mesothelium, as well as to the submesothelial connective tissue and lymphatics, by repetition of ovulation. It is possible that liplike stomal orifices may be formed in the process of repairing the damage.

Age Factors↗

PubMed1986

The causal agent of halo blight in bean, Pseudomonas syringae pv. phaseolicola, attaches to stomata via its pili.

The phytopathogenic pseudomonad Pseudomonas syringae pv. phaseolicola causes halo blight of bean (Phaseolus vulgaris L.). Initiation of infection depends on the ability of the cells to adhere to the target cell surface. P. syringae pv. phaseolicola expresses pili, which are the receptors of the lipid-containing dsRNA bacteriophage phi 6. phi 6-resistant bacterial strains can be divided into different piliation types. It was possible to show that the adhesion of the bacteria onto plant cell surface was dependent on the pili. Non-piliated bacterial stains showed a much lower adherence to the leaf surface than strains expressing phi 6 specific pili. Scanning electron microscopy showed that the piliated bacteria attached to the leaf surface at the site of stomata. Non-piliated bacteria were evenly distributed on the leaf surface. All bacterial strains used in this study were capable of causing halo blight if injected into the plant. If the bacteria were sprayed on the plants, followed by spraying of sterile buffer, only piliated bacteria caused symptoms.

Bacterial Adhesion↗

PubMed1978

The use of pure carbon stomata (Biocarbon) in urinary diversion.

A new synthetic material, Biocarbon, has the advantages of tissue compatibility and chemical inactivity, so that there is minimal salt sedimentation. Experiments with animals extending over a period of more than 2 years showed good healing after various surgical and urological operations. Biocarbon stomata were then used for vesicostomies in 6 patients. The period of follow-up has been months. We conclude that Biocarbon implants used for ureterocutaneostomies and for various conduit operations can improve tthe care of stomapatients.

Animals↗

PubMed1987

Graft reconstruction to treat disease of the abdominal aorta in patients with colostomies, ileostomies, and abdominal wall urinary stomata.

Abdominal aortic reconstruction combined with colon or urinary tract operations is generally not acceptable because of a supposed greater incidence of graft infection. Similar fears exist regarding aortic reconstruction in the presence of colostomies, ileostomies, and permanent urinary diversion stomata. In fact, the presence of a colostomy has been reported to be a contraindication for abdominal aortic reconstruction. This report is concerned with vascular operations in 13 such patients with aortic disease referred to us for fear of these complications. Eleven patients had abdominal aortic aneurysms and two had atherosclerotic occlusion of the aorta and iliac arteries. Twelve patients had colostomies, ileostomies, or both and one patient had permanent tube cystostomy. All had good renal function and the disease for which the diversion procedure was performed was either cured or under good control. All patients survived the vascular reconstructive procedures without significant complications and long-term follow-up revealed that late graft infection did not occur.

Abdominal Muscles↗

PubMed1988

Postinflammatory increase of lymphatic absorption from the peritoneal cavity: role of diaphragmatic stomata.

During the healing phase of a chemical peritonitis in rats, absorption of various inocula from the peritoneal cavity into the draining lymph nodes is increased. Heretofore, this phenomenon has been attributed to fibrosis and shrinkage of the greater omentum. The loss of the sequestering function of the omentum allows the inoculum more ready access to the lymphatic vessels in the diaphragm where it is absorbed. In the present work, it is demonstrated that the chemical peritonitis also widens the stomata in the roofs of the diaphragmatic lymphatic lacunes. Both increased access and larger openings contribute to enhanced lymphatic absorption in the postinflammatory state.

Absorption↗

PubMed1979

[Carbon polymer stomata in vesicostomy and other urinary diversion procedures (author's transl)].

Implants of pure carbon are ideal for prosteses because of their tissue acceptability and lack of incrustation. Animal experiments with biocarbon implants were tested as subfascial implantations, coeco-, ileo-, and vesicostomies, (n = 37). The results showed lack of reaction and good healing of the stomata, lack of incrustation, and water tight urinary diversion. Based on these animal experiments biocarbon vesicostomies were carried out successfully in six patients. The follow up period was 3--16 months.

Animals↗