Abstract: A convenient low-cost system is disclosed for digitally displaying instrument locations during a stereotaxic procedure on an animal such as a rat or mouse. This system, which can be retrofitted onto most types of existing stereotaxic manipulators, uses three optical or capacitance scaling devices, mounted orthogonally. An electronic reader head interacts with each scaling device, to measure the position and travel of the manipulator along the medial-lateral (X), anterior-posterior (Y), and dorsal-ventral (Z) axes. Each reader head sends electronic signals to a small display box that can be placed or mounted in any convenient location, or to a computer with a monitor, and all three coordinates are displayed continuously. This system provides a simple zeroing function, which can set all values to zero when an instrument tip reaches a fixed location such as the bregma point on a skull.

Abstract: A dry break coupling for joining together opposing passageways includes a male member and a female member, each of which includes a resiliently deformable rubber flap with cross-hair slits positioned to engage each other as the male and female members are moved axially toward their coupled position. Each of the male and female members also is provided with a normally closed but resiliently openable rubber septum position on the opposite side of its rubber flap from the engagement end of the respective members. The male member is provided with a blunt cannula which is fixed and a moveable carrier supporting the rubber septum. The female member is provided with an axially moveable support for the rubber flap and a fixed support for the rubber septum.