Ductal Architecture: Corrosion Casting of Canine Mammary Glands Using an Intraductal Approach

Detailed knowledge related to the morphology, anatomy, physiology, and pathology of the canine mammary gland is scarce. Mammary tissue undergoes massive changes instructed by hormones multiple times within the lifespan of every bitch, affecting its appearance. To address the ductal system's appearance and to present how different our findings regarding the canine mammary gland are in comparison with the available literature, we obtained cadaveric specimens after euthanasia and mastectomy. All bitches were euthanised due to poor prognosis for their recovery from maladies unrelated to mammae. Using intraductal cannulation ex vivo, milk- or fluid-yielding ducts were perfused using VasQtec (polyurethane resin), which revealed casts, i.e., imprints of ducts and glandular structures in situ. We observed primary, vertically positioned ducts that ascended throughout the teat and continued branching to secondary, tertiary, etc., horizontally positioned ducts, which drained mammary gland lobes under the skin located close to the abdominal wall. The ascendant teat canal could be split into two and could be connected to gland alveoli or end blind. Alveolar formations were located along ducts and ductules in bigger and/or smaller clusters. This study is the first to generate a 3D image of canine ducts and glandular tissue using an intraductal approach.