Microscopic analysis of high porosity chambers implanted subcutanteously into control and Fib^−/− mice.

Panels A, C, and E show microscopic sections prepared from control mice; panels B, D, and F show sections prepared from Fib^−/− mice. Panels A and B show implants left in place for 7 days and panels C-F show implants left in place for 21 days. Panels A-D were stained with hematoxylin and eosin; panels E and F were stained for fibrin(ogen) by immunohistochemistry (brown reaction product). The inside and outside boundaries of the porous tubing are indicated with arrowheads and arrows, respectively. Note that by day 21 the walls of the porous tubing are heavily infiltrated with cells regardless of the presence or absence of fibrin(ogen). Also note that dense fibrillar material (asterisk) containing fibrin(ogen) is present within the lumen of implants of control mice, and this is deeply infiltrated with cells (C and E). In contrast, only amorphous material is present within these spaces in Fib^−/− mice and cells are only found proximal to the luminal surface of the implants.