| Objective :To establish a mouse’s cross-territory ear flap that enables chronic, in-vivo observation of the change of vascular morphology.Methods:60 ICR mice, weighing 25-30 g, were used for this study. Commercial depilatory cream was used to first remove the hair of the mice, after which the vascular pattern in the ears was investigated. According to the observation of the vascular pattern in the mouse’s ear, the eye scissors were used to sever the outer 2/3 of the base of the ear, in which process an ear’s flap based on a vascular pedicle but crossed three vascular territories was created. The left-ear is the control group, which just underwent removal of the hair. After the creation of the flaps, the mice were placed on an automatic controlled movable machine with the ear’s flaps spread over a customized Plexiglas. Then the flaps were photographed under the stereoscope(2.5×10) at the following time points: 1, 2, 3,5,7, 10, 14,21,30 d. The necrosis of the flap, and the morphological change of the vessels with in the flap were analyzed. Pathological section and immunohistochemistry were performed for further study of the choke vessels. Then the flaps were photographed under the stereoscope(×100)at the following time points: 0, 1,3,5,7d.. The harvested flaps were fixed in 10 precent of Formaldehyde, underwent HE staining. Analysis the number of choke vessels and the change of MCP-1、ICAM-1、CD-68 was performed.Results :①The ICR mouse’s ear was supplied by three angiosomes, which were respectively named as the cephalic, median and caudal angiosomes from inside out. Five days after the flap’s creating, necrotic rate of(15±7)% was developed. The choke vessels between the medial and median angiosomes expanded rapidly in diameter, reaching the plateau 10 d after flap creation, resulting the dilated choke veins and arteries at their peak being 3.9±0.5 and 3.5±0.7 fold, respectively than their initial sizes. The diameter of the choke veins began to shrink at approximately 10 d, stabilizing after 21 d. The diameter of the choke arteries plateaued and stabilized at around 10 d. ② Blood volume of ChokeⅠ area increased over time, while blood volume of Choke 2 area did not improve significantly. Filling of arteries and veins of the ChokeⅠ were full in 1 day and 3 days; Filling of vessels in ChokeⅡ declined immediately, but increased on the following day, being not significantly different for the control group on day 7③ In the 0 day, expression of ICAM-1 and CD-68 of the ChokeⅠ and ChokeⅡ increased significantly, but the MCP-1 expression level was not significantly different from the control group. the three factors of the experimental group and control groups had statistical significance in expression(P < 0.01), and were significantly correlated to the blood vessel diameter changes.Conclusion: ①after harvest of the extended flap, the dilation of veins seemed to passive, whereas the dilation of arteries seemed to be active; ② the number of the choke vessels between the dynamic and potential territories that are involved in dilation and extent of the dilation are much smaller than that of the choke vessels between the anatomic and dynamic territories;③ the mouse’s ear flap is an excellent model of further study of mechanism underlining the dilation of choke vessels and for the screening of vasoactive drugs that could augment the survival of a large flap. ④ICAM-1、CD68、MCP-1 is positively involved in the dilation of vessels. The influence of excessive inflammation is subject for further research... |
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