A holding system comprising a coupling device for the self-securing mechanical connection of two parts (100, 20) of a holding system for medical instruments, comprising: a bolt element which can be inserted into a bushing; wherein the bushing has a main body and a cone sleeve firmly connected thereto, which tapers conically at its free end, wherein a spring-loaded, clamping body-guiding cage sleeve is inserted axially movably into the cone sleeve; wherein (a) clamping bodies can be arranged so as to protrude radially beyond the inner circumferential edge of the cone sleeve in an uncoupled position (a) by means of the spring force acting on the cage sleeve; (b) the clamping bodies can be moved radially inwards in a release position (b) by displacing the cage sleeve against the spring force along the cone inner surface in order to release the inner circumference of the bushing for the bolt element; and (c) the clamping bodies can be snapped into a coupling groove of the bolt element in a locking position (c) by means of the spring force; wherein the inclined coupling groove flank of the bolt element, at the front in the insertion direction, forms an angle α with the longitudinal axis of the bolt element; wherein the cone inner surface of the cone sleeve forms an angle β with the central sleeve axis; and wherein, for the self-securing connection, the angle α is designed to be larger than the angle β in order to press clamping bodies, which are partially or completely snapped into the coupling groove, into the locking position (c) counter to the insertion direction by application of a tensile force (Fz) to the bolt element, wherein a first part of the holding system is a clamping device; and wherein a second part of the holding system is a holding device for medical instruments, wherein the main body of the bushing is designed such that the end of an axially displaceable pushing element of the clamping device can be arranged to protrude into the main body; and wherein the bolt element can be connected to a proximal holding segment of the holding device such that the proximal end of a pushing element, which can be displaced in the holding segment and in the bolt element, can be arranged so as to protrude beyond the front side of the bolt element; and wherein, in the locking position (c) of the coupling device, the proximal end of the pushing element of the coupled holding device can be axially displaced for frictional locking counter to the insertion direction of the bolt element by means of the pushing element of the clamping device, which can be displaced via a spindle. a bolt element which can be inserted into a bushing; wherein the bushing has a main body and a cone sleeve firmly connected thereto, which tapers conically at its free end, wherein a spring-loaded, clamping body-guiding cage sleeve is inserted axially movably into the cone sleeve; wherein (a) clamping bodies can be arranged so as to protrude radially beyond the inner circumferential edge of the cone sleeve in an uncoupled position (a) by means of the spring force acting on the cage sleeve; (b) the clamping bodies can be moved radially inwards in a release position (b) by displacing the cage sleeve against the spring force along the cone inner surface in order to release the inner circumference of the bushing for the bolt element; and (c) the clamping bodies can be snapped into a coupling groove of the bolt element in a locking position (c) by means of the spring force; (a) clamping bodies can be arranged so as to protrude radially beyond the inner circumferential edge of the cone sleeve in an uncoupled position (a) by means of the spring force acting on the cage sleeve; (b) the clamping bodies can be moved radially inwards in a release position (b) by displacing the cage sleeve against the spring force along the cone inner surface in order to release the inner circumference of the bushing for the bolt element; and (c) the clamping bodies can be snapped into a coupling groove of the bolt element in a locking position (c) by means of the spring force; wherein the inclined coupling groove flank of the bolt element, at the front in the insertion direction, forms an angle α with the longitudinal axis of the bolt element; wherein the cone inner surface of the cone sleeve forms an angle β with the central sleeve axis; and wherein, for the self-securing connection, the angle α is designed to be larger than the angle β in order to press clamping bodies, which are partially or completely snapped into the coupling groove, into the locking position (c) counter to the insertion direction by application of a tensile force (Fz) to the bolt element, wherein a first part of the holding system is a clamping device; and wherein a second part of the holding system is a holding device for medical instruments, wherein the main body of the bushing is designed such that the end of an axially displaceable pushing element of the clamping device can be arranged to protrude into the main body; and wherein the bolt element can be connected to a proximal holding segment of the holding device such that the proximal end of a pushing element, which can be displaced in the holding segment and in the bolt element, can be arranged so as to protrude beyond the front side of the bolt element; and wherein, in the locking position (c) of the coupling device, the proximal end of the pushing element of the coupled holding device can be axially displaced for frictional locking counter to the insertion direction of the bolt element by means of the pushing element of the clamping device, which can be displaced via a spindle.