Disclosed is a device for preparing a layer of biological cells on a deposition surface of a slide, the device including a body provided with a channel, the body including a first end forming an inlet tip intended to enter inside a container containing a biological liquid, closed by a cap and a second end forming a depositing tip intended to deposit a drop of the liquid on the deposition surface, the second end including a spreader with a blade arranged in a plane forming an angle of inclination α with the plane of the deposition surface and elastic return interposed between the blade and the second end.