Analysis of Gross and Histopathologic Changes from Repeated Celiotomies in African Clawed Frogs (Xenopus laevis)

Repeated survival surgical oocyte collection in African clawed frogs (Xenopus laevis) is commonly performed to access high-quality, viable oocytes for research procedures and to reduce the number of animals used in research. Despite this common practice, there is no evidence-based limit for the total number of survival celiotomies that can be performed. To provide an improved reference, a retired colony of experimental frogs (n = 31) was euthanized for gross and histopathologic evaluation and then compared with 4 experimentally naive age-matched controls (n = 4). Experimental animals underwent 4-11 celiotomies (average 6 ± 2) and were between 180 and 1,646 days (average 448 ± 245.2 days) from their last surgery. Body weight, residual skin, and coelomic wall sutures were counted. Surgically incised skin and coelomic wall musculature were collected for histopathology. A cumulative skin score and a coelomic wall score were developed to reflect all histopathologic evidence of acute and chronic inflammation. The cumulative skin score was significantly predicted by the number of surgeries (P = 0.003), but not predicted by the number of skin sutures remaining (P = 0.14). The coelomic wall score was significantly predicted by the number of coelomic sutures placed (P < 0.001) and the number of surgeries (P < 0.001). Neither one of the histopathology scores correlated to the number of days since the last surgery (P > 0.2). As one would expect, increasing the number of surgeries and coelomic sutures correlated with the histopathologic finding of a chronic inflammatory process in the skin. Although a specific recommendation for a maximum number of surgeries could not be discerned, this study provides an improved reference for Xenopus survival surgical oocyte collection underscoring the recommendation to use absorbable sutures within the body cavity and to remove all external nonabsorbable sutures 10-14 days postoperatively.