An apparatus for automated processing of a biological specimen on a substrate for examination, the apparatus comprising a platform having a top surface located opposite the substrate in a specimen processing position and comprising at least one fluid port (42A-45A) located on a surface of the platform facing the substrate and at least one vacuum port located on the surface of the platform facing the substrate ; wherein, in the substrate processing position, the substrate and top surface of the platform are substantially parallel and form a separation, wherein during operation, the apparatus is configured to circulate fluid between the at least one fluid port (42A-45A) and the at least one vacuum port by: (a) dispensing a first quantity of fluid from the at least one fluid port (42A-45A) to fill the separation between the substrate and the platform ; (b) dispensing an additional quantity of fluid from the at least one fluid port (42A-45A) into the separation to displace a portion of the first quantity of fluid; and (c) removing the portion of the first quantity of fluid from the separation through the at least one vacuum port ; and wherein the apparatus is further configured to dispense multiple additional quantities of fluid from the at least one fluid port (42A-45A) into the separation to displace portions of fluid from the separation and remove the displaced portions of fluid through the at least one vacuum port , wherein the apparatus is further configured to continuously dispense the additional quantity of fluid and to remove the portion of the first quantity of fluid or wherein the apparatus is further configured to alternately dispense the multiple additional quantities of fluid and remove the displaced portions of fluid to generate a pulsatile flow of fluid between the at least one fluid port (42A-45A) and the at least one vacuum port . a platform having a top surface located opposite the substrate in a specimen processing position and comprising at least one fluid port (42A-45A) located on a surface of the platform facing the substrate and at least one vacuum port located on the surface of the platform facing the substrate ; wherein, in the substrate processing position, the substrate and top surface of the platform are substantially parallel and form a separation, wherein during operation, the apparatus is configured to circulate fluid between the at least one fluid port (42A-45A) and the at least one vacuum port by: (a) dispensing a first quantity of fluid from the at least one fluid port (42A-45A) to fill the separation between the substrate and the platform ; (b) dispensing an additional quantity of fluid from the at least one fluid port (42A-45A) into the separation to displace a portion of the first quantity of fluid; and (c) removing the portion of the first quantity of fluid from the separation through the at least one vacuum port ; and (a) dispensing a first quantity of fluid from the at least one fluid port (42A-45A) to fill the separation between the substrate and the platform ; (b) dispensing an additional quantity of fluid from the at least one fluid port (42A-45A) into the separation to displace a portion of the first quantity of fluid; and (c) removing the portion of the first quantity of fluid from the separation through the at least one vacuum port ; and <EOS>