Khillan responds:

I would like to emphasize that the article by Dawes and colleagues1 describes not only a procedure for ovarian transfer but also an unusual situation that required multigenerational transfers of ovaries to rescue a valuable transgenic line. From time to time, some investigators face a situation where a valuable transgenic line of mice is in jeopardy. Creation of a new line of mice is a huge investment that, apart from being expensive, can take between 6 and 8 months. Moreover, the same transgenic founder can never be recreated. Although ovarian transfer is a well-established procedure, the success cannot always be guaranteed, especially when the amount of available tissue is limited.

In the situation described in our paper, there was only one donor, the transgenic founder female mouse1. Under normal circumstances, this one ovarian transfer would be enough to save the transgenic line. However, when we bred this recipient female, the female generated only one transgenic pup (a female) that was of poor health. We were unable to continue the transgenic line by breeding this female transgenic progeny. Upon dissection, we found that the ovaries of this transgenic progeny were poorly developed. We transplanted the ovaries from this female into a recipient female. Though the starting ovarian tissue was of poor quality, we were able to breed the recipient female, to obtain transgenic progeny and eventually to establish a transgenic line. This article provides valuable information that may help investigators save time and money and precious transgenic lines that otherwise may be lost.