Histology of the rectus abdominis muscle in rats subjected to cranial and caudal devascularization.

Purpose: To investigate the microscopic changes in the rectus abdominis muscle in rats subjected to five delay procedure.

Methods: 30 male Holtzmann rats, weighting between 250 and 350 grams, were used. The animals were divided into five groups (n=6): A - cranial section of the right muscle; B - caudal section of the right muscle; C - craniocaudal section of the right muscle; D - cranial section reflecting the right muscle in the craniocaudal direction; E - caudal section reflecting the right muscle in the caudocranial direction. On the seventh day after surgery, a resection of the cranial and caudal fragments of the right and left muscles, respectively, was performed for microscopic analysis. Histological alterations were quantified and the right and left (control) muscle fragments compared. Fisher's exact test was used for statistical purposes with a significance level of 5%.

Results: The comparison between right and left muscles showed statistically significant differences in group A - inflammatory infiltrate in the cranial fragment (p=0.015); in group C - inflammatory infiltrate (p=0.000) and necrosis (p=0.015) in the caudal fragment; and in group E - edema in the caudal fragment (p=0.000). No significant alterations were noted in groups B and D.

Conclusions: Irrigation exclusively through the perforating muscle vessels is inappropriate; irrigation exclusively through the cranial pedicle causes milder, insignificant histological alterations, when compared with irrigation exclusively through the caudal pedicle; irrigation exclusively through the caudal pedicle causes more pronounced, but still insignificant, histological alterations when compared with other forms of devascularization.