Comparison of mouse mammary gland imaging techniques and applications: Reflectance confocal microscopy, GFP Imaging, and ultrasound

We evaluated three techniques that can be quickly applied to living tissue for imaging normal and cancerous mammary gland: reflectance confocal microscopy, green fluorescent protein imaging, and ultrasound imaging.In the current study, reflectance confocal imaging offered the highest resolution and was used to optically section mammary ductal structures in the whole mammary gland. Glands remained viable in mammary gland whole organ culture when 1% acetic acid was used as a contrast agent. Our application of using green fluorescent protein expressing transgenic mice in our study allowed for whole mammary gland ductal structures imaging and enabled straightforward serial imaging of mammary gland ducts in whole organ culture to visualize the growth and differentiation process. Ultrasound imaging showed the lowest resolution. However, ultrasound was able to detect mammary preneoplastic lesions 0.2 mm in size and was used to follow cancer growth with serial imaging in living mice.In conclusion, each technique enabled serial imaging of living mammary tissue and visualization of growth and development, quickly and with minimal tissue preparation. The use of the higher resolution reflectance confocal and green fluorescent protein imaging techniques and lower resolution ultrasound were complementary.Transgenic mouse models have been developed to recapitulate the complex effects of genes known to be involved in human breast cancer. These models can help to elucidate the mechanism of action of these genes during carcinogenesis, as well as their impact on normal mammary gland development. Imaging methods for mouse models of normal and cancerous mammary glands are in the developing stages and can help in the search for better ways to diagnosis human breast cancer earlier [1].In order to study early phenotypic effects of gene over-expression or lack of expression on mammary gland development and cancer traditional methods require that tissue is harvested from the animal and subje