True Vessels Research Articles

Determinants of transvascular fluid shifts in zone I lungs.

We studied the fluid shifts in isolated, plasma-perfused rabbit lungs kept completely within zone I. The rate of fluid filtration or reabsorption was determined gravimetrically. A rise in alveolar pressure at constant pleural and vascular pressures reduced th rate of filtration or increased the rate of reabsorption in seven of eight lungs. In seven of seven lungs a reduction in pleural pressure at constant alveolar and vascular pressures increased the rate of filtration or decreased the rate of reabsorption. Thus, a given rise in lung volume had opposite effects depending on whether this rise was caused by an increased alveolar or reduced pleural pressure. Therefore, the exchange vessels studied cannot be true extra-alveolar vessels, which always expand (reflecting a rise in transmural pressure) with a rise in lung volume. When alveolar and pleural pressures were equally increased at constant vascular pressure, the rate of filtration was reduced in four of four lungs. The results can be explained through the existence of exchange vessels situated neither in the alveolar septae proper nor among the true extra-alveolar vessels. The vessels in the alveolar junctions are the most likely candidates.

Tracheary elements in Ophioglossaceae

AbstractTracheary elements have been investigated in root, rhizome and petiole of 10 species covering all the three genera of the family. True vessels are observed only in Helminthostachys, rest of the taxa shows typical tracheids. Protoxylem elements mostly show irregular thickenings. Simple annular and simple helical tracheids are rare in this family. Different lines of specialisation based upon the sequence and ontogeny of the metaxylem elements have been traced as they follow a variety of thickening patterns. These elements in Helminthostachys and Botrychium culminate in tracheids with typical circular bordered pits. Pits in Ophioglossum are irregular with low borders and wide pores. Branched tracheids are observed in the rhizome in all the three genera. Tracheary elements are found to be longest in petiole, shortest in rhizome and median in root.

Volume of the capillary exchange vessels measured with a gravimetric method in rat hindquarters

To measure the volume of the true exchange vessels, i.e., that of the “functional” capillaries, in rat skeletal muscle, two parallel-coupled hindquarter vascular beds were perfused at a constant flow with oxygenated plasma substitute. Continuous recordings were performed of changes in the total weight of the two preparations, caused by sudden arterial occlusion in one, thus doubling the flow to the other while venous drainage was left open in both. Venous outflow pressure was kept constant, usually at a level where the veins remained well distended. After a rapid and small change in total weight, reflecting the balance between vascular distension and recoil in the two circuits, the subsequent weight change showed a continuous increase, but after a distinct delay. From this delay, caused by transient absorption into the semistagnant capillary contents of the arterially occluded vascular bed, the absorbed fluid amount, Q, was calculated. Functional capillary volume, V c, was then calculated from the following equation (see text for derivation): V c= Q ln [ π c π c−P c+P v ] where π c, P c, and P v represent effective plasma colloid osmotic pressure, equivalent capillary pressure, and venous outflow pressure during isogravimetric conditions. This functional capillary volume, which thus includes permeable venular sections, amounted to 0.55–0.60% of the tissue weight, varying slightly with the prevailing P c, and corresponding to 10–15% of the total volume of the regional vascular bed. Capillary density in skeletal muscle was also deduced from these data and from known microvascular diameters, giving a value of 450–500/mm 2, which is in fair agreement with morphological data. The physiological significance of measuring the functional capillary volume by this method is discussed.

Microcirculation in diabetes mellitus: A Study of gingival biopsies

Gingival biopsy specimens from 24 diabetic patients, six obese.persons, and six controls were studied statistically and morphologically to detect vascular basement membrane changes using a proposed classification of microvessels. Statistically significant basement membrane thickening is seen in all diabetic groups in most true capillaries and vessels proximal to them, especially in terminal arterioles and metarterioles, although the degree and extent of the changes vary among different clinical groups and vessel types. The basement membrane thickening is characterized by increased amorphous, granular, and fibrillary material with occasional scattered collagenous fibrils. Although nonspecific, basement membrane thickening in microvessels at, and especially proximal to, the level of true capillaries is intimately related to diabetes. Gingival biopsy may possibly be used as an adjunct in the diagnosis of diabetes. * Clinical Assistant Professor of Patltology, Health Sciences Center, State University of New York at Stone Brook. Associate Pathologist, Department of Pathologe and Laboratories, Nassau County Medical Center, East Meadow, New York. † Associate Professor of Pathology, Health Sciences Center, State University of New York at Stone Brook. Associate Chairman, Department of Pathology and Laboratories, Nassau County Medical Center, East Meadow, New York. ‡ Associate Professor of Medicine, State University of New York at Stony Brook- Chief, Division of Endocrinology,Departntent of Medicine, Nassau County Medical Center, East Meadow, New York.

Ultrastructure of lymphatic vessels in the vascularized rabbit cornea

A carbon suspension was injected into rabbit corneas vascularized as a result of silver nitrate application. Both light and electron microscopic techniques were used to study the carbon-filled corneal lymph vessels. The corneal lymphatics have a structure similar to that of lymphatic vessels in other sites. The endothelium is thin, there are no pericytes and no basement membrane and anchoring filaments are present. Hence, they are true corneal lymphatic vessels.

Blood gas changes following Priscoline administration in mitral stenosis and chronic lung diseases

The O 2 and CO 2 content in the arterial blood of normal individuals and of patients with mitral stenosis and with chronic lung disease were examined in the resting state and ten minutes after the intravenous administration of Priscoline. In about half of the normal individuals a drop in the O 2 content was observed after the drug; however, this change was statistically nonsignificant. In the majority of patients with mitral stenosis and with chronic pulmonary disease a statistically significant drop of the O 2 content was observed while changes in the CO 2 content varied. The observed drop in the arterial O 2 content after administration of a drug known to cause vasodilation and augmented cardiac output is thought to be brought about by increased perfusion of poorly ventilated areas in the lungs and/or by increased flow through true intrapulmonary shunt vessels.

The anatomical structure of the Xanthorrhoeaceae Dumort.

SUMMARY The anatomical structure of different plant organs of nearly all the species of the eight genera of the Xanthorrhoeaceae has been described. The xylem elements of representative species of all the genera have been investigated in macerated material. True vessels have been found in the roots of all the genera, and in the leaves of Xanthorrhoea and Acantho-carpus. No tracheal elements except tracheids have been seen in the leaves of the other genera, or in the stems or rhizomes of all the genera. When these data are compared with those established by Cheadle (1942) for other families of the monocotyledons, it will be seen that the Xanthorrhoeaceae most closely resemble the Agavaceae. Amphivasal vascular bundles occur in the stems and/or rhizomes of all the genera except Kingia where the xylem in all the bundles is U-shaped in transverse section. The stem structure of Xanthorrhoea provides evidence that the amphivasal type structure has arisen by the fusion of pairs of bundles with U-shaped xylem. The leaves of all the genera have a xero-morphic anatomical structure. Special arrangements and structures, which prevent excessive evaporation occur in the stomatal regions in Xanthorrhoea, Kingia and Baxteria. A special type of palisade cell with annular contractions, and/or with papillose projections, occurs in Kingia, Calectasia, Lomandra and to a lesser extent in Dasypogon, and traces of this type of structure are also to be seen in the other genera of the family.

THE TRACHEAL ELEMENTS IN THE FERNS

THE TRACHEAL ELEMENTS IN THE FERNS

The Anatomy and the Histology of Bud-formation in the Serpulid Filograna implexa, together with some Cytological Observations on the Nuclei of the Neoblasts.*

The Anatomy and the Histology of Bud-formation in the Serpulid Filograna implexa, together with some Cytological Observations on the Nuclei of the Neoblasts.*

ACUTE MENINGITIS.

By the term meningitis is understood inflammation of the pia arachnoid, the investing membrane of the brain and spinal cord. Considered as a single membrane, it consists of a serous surface (arachnoid) forming one side of the subdural space and beneath this a loose connective tissue, the pia mater, which carries the blood vessels for the brain and cord. The brain, covered by this membrane, projects into the subdural space as the heart projects into the pericardial cavity. In addition to the vessels, there are numerous lymphatics, which are situated in the adventitial sheaths of the veins and arteries and which are continued with these vessels into the brain. They are true lymphatic vessels with an endothelial lining; they are thin-walled, and, when distended, communicate freely with the tissue spaces. There are no lymphatics in the tissue of the brain itself, nor have lymph spaces, similar to the spaces