Fig. 6.

Schematic drawing of the blood supply to the different layers of the integument of the ventrolateral aspect of the abdomen of the rat. The integument of the rat is composed of the skin, a fatty layer known as panniculus adiposus, and beneath this latter layer of a sheath of loose connective tissue associated with white adipose tissue and smooth muscle forming a layer known as panniculus carnosus. This layer is located just above the abdominal wall muscles and muscle fascias. There is a loose areolar tissue beneath the panniculus carnosus and the muscle fascia. The integument presented the following plexuses: a loose and thin prefascial plexus in the prefascial areolar tissue; a dense and thin panniculus carnosus plexus encompassing the entire thickness of this layer and mostly dependent on the direct cutaneous axial vessels. This plexus was mostly composed of third-order arterioles and venules, as well as capillaries; a loose panniculus adiposus plexus, mainly composed of obliquely disposed ascending and descending first-order arterioles and venules, respectively, supplying the overlying layers and the adjacent fatty tissue; a subdermal plexus at the upper portion of the panniculus adiposus, immediately beneath the skin, composed of second-order arterioles and venules with a horizontal orientation; a reticular dermal plexus composed of vertically arranged third-order ascending and descending arterioles and venules, respectively, as well as their terminal branches, which formed capillary networks around sebaceous dermal glands and the papillae of hair follicles; a subpappilary dermal plexus, at the dermal-epidermal interface, composed of capillary loops with a predominantly horizontal disposition interspersed with occasional vertical capillary loops. These capillaries were in continuity with the vertical arterioles and venules of the reticular plexus. Blue structures represent veins. Red structures represent arteries. 1, Subpapillary vascular plexus; 2, subdermal vascular plexus; 3, superficial arteriole in the panniculus adiposus; 4, panniculus carnosus vascular plexus; 5, arterioles and venules supplying the prefascial vascular plexus in the prefascial areolar tissue; 6, fascial vascular plexus; 7, subfascial vascular plexus.