Scanning Microscopy


Tissues from fourteen mammary glands of eight bitches were prepared for scanning electron microscopy of vascular corrosion casts and for histology to study the vasculature of the lactating and non-lactating teats. 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 oriented to the ducts. Between eight and fifteen teat duct openings were seen on the tip of the teat, that were sometimes divided by a septum. The inner vascularization of the teat showed that the main papillary arteries divided into undulating secondary papillary arteries which presented numerous semi-constrictions and loops. Their structure may help during erection of the teat. Arteriovenous anastomoses found at different points may participate in blood flow maintenance during suckling, heat regulation and teat erection. Veins freely anastomosed and ran longitudinally to the axis of the teat. They exhibited numerous bicuspid valves. In non-lactating teats, vessels showed the same main architecture and characteristics mentioned above, although these were considerably less marked. The structure of the vascular elements in the teat of the bitch could favor blood flow during suckling and suggest that vessels adapt to the physiological situation.

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