Arboix Arzo, Margarita

Carretero i Romay, Ana

Navarro Beltrán, Marc

Pérez Aparicio, Francisco Javier

Ruberte París, Jesús

Ruberte, Jesús

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AI/era/iollS ill derelof'lIIeIl/ 2875EFFECT OF THE ACIDOSIS ON THE DEGERATING MESONEPHRIC VASCULAR SYSTEM OF THE CHICK EMBRYOSMarc NAVARRO, Ana CARRETERO, Francisco Javier PEREZ-APARICIO, Margarita ARBOIX', Jesus RUBERTEDepartment of Anatomy and Embryology. .Department of Pharmacology. Veterinary Faculty. Autonomous University of Barcelona.08193-Be/laterra, Barcelona. SPAINThe mesonephros of the chick embryo is a temporary organ thatoffersthe possibility to study both vascular growth and degenerationin the same modei under physiological conditions. We know fromprevious studies that the mesonephros at the stage 41 H-H(Hamburger and Hamilton, 1951) presents a severe degeneration(Carreteroetal., 1993; 1995; 1996). The aim of this work istostudythe effect of the acidosis on thedegenerating mesonephric vascularsystem of the chick embryos.Thirty embryos of commercially bred chicken (Gallus domesticus;White Leghorn) were used in this study. Eggs were divided intotwo groups: 15 embryoswere injected into the primitive intestinewith 10mlofHCI 0.1 N, usingaHamilton microliter syringe througha window in the shell, at 56-60 hours of incubation (stage 16-17H-H); and 15 embryos were used as controls. The windows weresealed and the eggs were reincubated until 15.5 days (stage 41 H-H), when the mesonephric degeneration is severe.Embryos were removed from the egg-shell and injected manuallythrough the umbilical vessels with Mercox@ diluted with methylmethacrylate (Carretero et aI., 1993). Subsequently, themesonephros were removed and corroded with KOH. The resultingcasts were mounted in stubs, sputtered with gold and observed ina Hitachi 5570 scanning electron microscopy.Observation of the casts showed that the main effects of theacidosis on the mesonephric vascular system were the loss of thenormal venous pattern and an increased angiogenesis.In some cases, the changes even consisted of loss of thetopography and normal disposition of great vessels such as thesubcardinal veins or the cava vein. Figure 1 shows the normalvascular pattern of a control embryo, in which several subcardinalveins of each mesonephros drain into the cava vein. On the otherhand, the anomalous venous pattern of a mesonephros treatedwith HCI 0.1 N (Fig. 2), showed different disposition and diametersof the subcardinal veins and loss of the topography of the cavavein.A high vascular density of certain areas of the mesonephricplexus of treated embryos could be observed (Fig. 3), whencompared with that of control embryos (Fig. 4), demonstrating anincreased angiogenesis induced by the acidosis. These areasshowed enlarged vesselssimilartovascular lacunae, where manyangiogenic structures, such as angiogenic holes, could be noticed(Fig. 5). The aspect of these vascular lacunae demonstrated thatthey were not extravasations of the injected resin, since theyshowed blood cell imprints on their surface (Fig. 6).Figure 1. Corrosion cast of the mesonephros of a control chick embryo.Ventral view. CV: Cava vein. P: Mesonephric plexus. (.) Subcardinal veins.Bar=0.7 mm.Figure 2. Corrosion cast of the mesonephros of a HCI treated chick embryo.Ventral view. Notice the anomalous pattern of the subcardinal vein!; (0) rindcava vein (CV), as well as the high density vascular areas in the mesonephricplexus (arrow). Bar = 0.6 mm.2885 Ai/erllliolls i/1 de\'('/op11ll'lIfNew interest about vasculogenesis and angiogenesis has arisen due to their close relation to tumoral neovascularization. It is wellknown that both hypoxia and anemia are potent "in vivo" and "in vitro" inducers of several angiogenic factors, such as the vascularendothelial growth factor (VEGF) (Plate et aI., 1992). These factors are inducible in human glioma ~ells. mouse fibroblast Lcells, ratcardiac cells, human mammary fibroblast, etc. Moreover, these factors are expressed during vasculogenesis and vasculardifferentiation in the quail embryo (Flamme et aI., 1995). These authors have observed an increase in vascular density of the avianlimb bud, similar to that observed by us in the mesonephros.In our study, we hypotetized that the increased angiogenesis could be due to the low pH produced by the HCI injection, inducinga similar mechanism as that produced by the pH decrease in hypoxia or anemia.Figure 3. Overview of the mesonephric plexus of a HCI treated chickembryo. Note the enlarged vessels that determine an increase of thevascular density. Bar=64 ~m.Figure 5. Detail of the plexus of figure 3, showing many angiogenicholes (arrows). Bar=1911m.ReferencesFigure 4. Overview of the mesonephric plexus of a contra! chickembryo. Bar=64 J.lm.Figure 6. Detail of the plexus cf figure 3. Note the blood cell imprintson the surface of the cast (arrows) that demonstrate the lack ofextravasation of the injected resin. Bar=16.5Ilm.Carretero, A., Ditrich, H., Navarro. M., Splechtna, H. and Ruberte, J. (1993) Technical improvements in corrosion casting 01 small specimens: A study on mesonephrictubules and vessels of chicken embryos. Scanning Microsc. 7: 1333-1338.Carretero, A., Ditrich, H., Perez-Aparicio, F.J., Splechtna, H. and Ruberte, J. (1995) Development and degeneration of the arterial system in the mesonephros andmetanephros of chicken embryos. Anal. Rec. 243: 120-128.Carretero, A., Ditrich, H., Navarro, M. and Ruberte,J. (1996) The afferent portal venous system in the mesonephros and metanephros of chick embryos: Developmentand degeneration. Anal. Rec. 246: ??Flamme, I., von Reutern, M., Drexler, H,C.A" Syed-AIi, S. and Aisau, W. (1995) Overexpression of Vascular Endothelial Growth Factor in tt1e avian embryo induceshypervascularization and increased vascular permeability without alterations of embryonic pattern formation. Dev. BioI. 171: 399-414.Plate, K.H., Breier, G., Weich, H.A. and Risau, W. (1992) Vascular endothelial growth factor is a potentiallumour angiogenesis factor in human gliomas in vivo. Nature359: 845-848.

Effect of the acidosis on the degenerating mesonephria vascular system of the chick embryos

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Effect of the acidosis on the degenerating mesonephria vascular system of the chick embryos

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