Plexiform vascular structures in the human digital dermal layer: a SEM--corrosion casting morphological study.

This study aimed to describe the impressive diversity of vascular plexiform structures of the hypodermal layer of human skin. We chose the human body site with the highest concentration of dermal corpuscles, the human digit, and processed it with the corrosion casting technique and scanning electron microscopy analysis (SEM). This approach proved to be the best tool to study these microvascular architectures, free from any interference by surrounding tissues. We took high-definition pictures of the vascular network of sweat glands, thermoreceptorial and tactile corpuscles, the vessels constituting the glomic bodies and those feeding the hair follicles. We observed that the three-dimensional disposition of these vessels strictly depends on the shape of the corpuscles supplied. We could see the tubular vascularization of the excretory duct of sweat glands and the ovoid one feeding their bodies, sometimes made up of two lobes. In some cases, knowledge of these morphological data regarding the normal disposition in space and intrinsic vascularization structure of the dermal corpuscles can help to explain many of the physiopathological changes occurring during chronic microangiopathic diseases.

Response of the infrared receptors of a crotaline snake to ethanol.

The pit organs of crotaline snakes can sense infrared (IR). The pit membrane has a finer, flatter, more convoluted vasculature than other sensory organs. Using extracellular recording from IR-sensitive trigeminal ganglion (TG) neurons (primary neurons) and tectal (OT) neurons of the crotaline snake Trimeresurus flavoviridis, we examined the IR response to ethanol (EtOH) in vivo. The response to EtOH was recorded in the TG and OT 20-80 s after 10% EtOH in Ringer's solution (100 microl/ 500 g body weight) was injected via the heart. The responses to EtOH and those to lower or higher temperature stimulation were additive. At a constant temperature (25 degrees C), EtOH significantly potentiated the IR-triggered discharges of IR-sensory pathways in this snake. These results suggest that the IR response to EtOH is due to either its vasodilatory effect on the abundant vasculature of the pit membrane or its chemical effect on temperature-sensitive receptors.