VASCULAR ARCHITECTURE OF THE LACTATING AND NONLACTATING TEAT OF THE BITCH - A SCANNING ELECTRON-MICROSCOPE AND LIGHT-MICROSCOPE STUDY

Tissues from fourteen mammary glands of eight bitches were prepared fo r scanning electron microscopy of vascular corrosion casts and for his tology to study the vasculature of the lactating and non-lactating tea ts. The densely-meshed mammary dermal capillary network formed ridges and troughs. The teat ducts were vascularized by a relatively densely- meshed capillary network which drained into veins longitudinally orien ted to the ducts. Between eight and fifteen teat duct openings were se en on the tip of the teat, that were sometimes divided by a septum. Th e inner vascularization of the teat showed that the main papillary art eries divided into undulating secondary papillary arteries which prese nted numerous semi-constrictions and loops. Their structure may help d uring erection of the teat. Arteriovenous anastomoses found at differe nt points may participate in blood flow maintenance during suckling, h eat regulation and teat erection. Veins freely anastomosed and ran lon gitudinally to the axis of the teat. They exhibited numerous bicuspid valves. In non-lactating teats, vessels showed the same main architect ure and characteristics mentioned above, although these were considera bly less marked. The structure of the vascular elements in the teat of the bitch could favor blood flow during suckling and suggest that ves sels adapt to the physiological situation.