This study examines, using an in vitro tissue bath technique, the nature of the transmitter mechanism(s) in the pig cerebral artery. Of the ar teries with intact endothelium, about 25% relaxed on application of acetyl choline (ACh) at low concentration (3 x 10-7 to 3 x 1O-6M) and constricted at concentrations exceeding 10-3M. The remaining arterial preparations either constricted (61%) or exhibited no response (14%) at any concentration of ACh tested (3 x 10-7 to 3 x 10-3M). On the other hand, none of the arteries without endothelium relaxed at any concentration of ACh tested (3 x 10-7 to 3 x 1O-3M); of these, 90% constricted and 10% exhibited no response. These re sults show that ACh-induced cerebral vasodilation is dependent on endothelial cells and the direct action of ACh on the vascular smooth muscle cells is constriction. Contrary to findings in the large cerebral arteries of the cat and several other species, about 90% of the pig cerebral arteries, with or without endothelium, dilated upon application of norepinephrine (NE) at low concen tration (107 to 3 x 1O-5M) and constricted at concentrations exceeding 3 x 10-5M. The NE dose-response relationships were not different in arteries with and without endothelial cells, indicating that the NE-induced vasodilation was independent of the endothelial cells. The relaxation and constriction were

A case of temporomandibular joint (TMJ) ganglion is described, and 4 previously reported cases are noted. In all cases, initial diagnosis of parotid neoplasm proved incorrect at surgical exploration. Management of all cases consisted of identification of the facial nerve and excision of the ganglion with a cuff of TMJ capsule. The diagnosis of TMJ ganglion should be entertained when a presumed parotid neoplasm changes in size or position with jaw movement.

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A case of acute thrombosis of an ulnar artery aneurysm in a patient with osteogenesis imperfecta tarda is described. The pathophysiology of osteogenesis imperfecta is reviewed and the possible association of defective collagen maturation and aneurysm formation is postulated. Most ulnar artery aneurysms or thromboses should be surgically resected and the artery repaired by microsurgical technique with primary anastomosis if possible or a venous interpositional graft if direct repair is not possible without tension.

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