There is increasing evidence that, in the rat, a serotonin-mediated neural input may have an inhibitory influence on the secretory activity of the subcommissural organ (SCO). In the present investigation the rat SCO was studied 7, 30 and 90 days after transplantation under the kidney capsule, an area devoid of local serotonin-containing nerves. The grafted tissue was examined by use of immunocytochemistry employing a series of primary antisera, lectin histochemistry and transmission electron microscopy. The grafted SCO survived transplantation and contained, in addition to secretory ependymal and hypendymal SCO-cells, also elements immunoreactive with antisera against glial fibrillary acidic protein or S-100 protein. In transplants, SCO-cells produced a material displaying the characteristic immunocytochemical and lectin-binding properties of SCO-cells observed under in-situ conditions. The ependymal cells lined 1-3 small cavities, which contained secretory material. A fully developed structural equivalent of Reissner's fiber was, however, never found. The immunocytochemical and ultrastructural study of the grafted SCO showed an absence of nerve fibers within the graft and suggested a state of enhanced secretory activity. A network of protruding basal lamina structures connected the secretory cells to the newly formed capillaries revascularizing the SCO. One week after transplantation, long-spacing collagen started to appear in expanded areas of such laminar networks and also in the perivascular space. It is suggested (i) that the formation of long-spacing forms of collagen is triggered by factors provided by the SCO-secretory cells, and (ii) that secretory material of the ependymal and hypendymal cells may reach the reticular extensions of the basal lamina. In contrast to the SCO in situ, the grafted SCO-cells showed a positive immunoreaction for neuron-specific enolase. They became surrounded by a S-100-immunoreactive glial sheath that separated them from other transplanted cell types and the adjacent kidney tissue of the host.

No abstract

We analyze the extent to which firm size determines the relationship between growth opportunities and bank debt in the Chilean corporate sector. Using generalized method of moments (GMM) system estimator techniques in an unbalanced panel data of quoted firms, we provide evidence of a U-shaped relationship between growth opportunities and bank debt, which has a different behavior depending on the firm’s size. Smaller firms seek private debt sooner than larger firms do when growth opportunities increase. This finding is supported by the institutional characteristics of the Chilean financial system, the higher confidence of small firms in bank debt, and the bank-based orientation of the Chilean financial markets

RESUMEN Nuestro objetivo es analizar la decisión de endeudamiento de las empresas españolas, considerando los problemas de información asimétrica, los costes de agencia y la estructura de propiedad. Las hipótesis se establecen teniendo en cuenta el entorno institucional al que pertenecen las empresas. Para el análisis se utiliza un panel de datos incompleto de 111 empresas adquiridas durante los años 1991-2001. Los resultados obtenidos indican que: i) La elevada concentración accionarial de las empresas españolas favorece el uso de la deuda para financiar sus oportunidades de crecimiento; ii) Las empresas con déficit de fondos recurren preferentemente, a los recursos externos mientras cuenten con una estructura de propiedad mayoritaria; iii) Las empresas cotizadas mantienen una velocidad de ajuste a su ratio de endeudamiento óptima distinta a la de las empresas no cotizadas y a la de las empresas de otros países.PALABRAS CLAVE Endeudamiento; Estructura de Propiedad; Oportunidades de Crecimiento; Entorno Institucional. SUMMARY Our aim is analyse the debt decision of Spanish firms, considering the asymmetry information problems, the agency costs and the ownership structure. The hypotheses are evolved taking in account the institutional environment where the firms perform their activity. The analysis uses an unbalanced data panel of 111 firms for the period 1991-2001. Our main results are: i) The high ownership concentration of Spanish firms favour the use of debt to finance the growth opportunities; ii) The firms with deficit of funds have more access to external funds if they have a majority ownership structure, y iii) Spanish quoted firms adjust to their debt target ratio at a different speed than other Spanish non quoted firms or than firms from other countries.

No abstract