An immunoassay test slide, which comprises: - a housing, the housing defining a cavity; and - a porous carrier matrix, the porous carrier matrix being disposed within the cavity of the housing for receiving a fluid sample containing an analyte, or one or more liquid reagents; wherein the housing includes a bottom side which is formed from a light transmissive material, a top side, the top side including a recessed portion to at least partially define the cavity for receiving the porous carrier matrix, a front side, a rear side situated opposite the front side, and opposite lateral sides, the cavity being situated between the front and rear sides (44, 46) and between the opposite lateral sides of the housing; and wherein the test slide further comprises: a top film portion, the top film portion being situated on the housing opposite the bottom side and in alignment with and covering the porous carrier matrix, the top film portion having an opening formed through the thickness thereof which is in communication with the cavity of the housing and which is provided to receive the fluid sample containing an analyte or the one or more liquid reagents, the porous carrier matrix being disposed within the housing and situated in alignment with the top opening formed in the film portion to receive thereon the fluid sample or the one or more liquid reagents; and wherein the top side of the housing includes at least one recessed ledge, the at least one recessed ledge being situated adjacent to the recessed portion which receives the porous carrier matrix, the at least one recessed ledge having a top surface on which a portion of the underside surface of the top film portion rests. - a housing, the housing defining a cavity; and - a porous carrier matrix, the porous carrier matrix being disposed within the cavity of the housing for receiving a fluid sample containing an analyte, or one or more liquid reagents; wherein the housing includes a bottom side which is formed from a light transmissive material, a top side, the top side including a recessed portion to at least partially define the cavity for receiving the porous carrier matrix, a front side, a rear side situated opposite the front side, and opposite lateral sides, the cavity being situated between the front and rear sides (44, 46) and between the opposite lateral sides of the housing; and wherein the test slide further comprises: a top film portion, the top film portion being situated on the housing opposite the bottom side and in alignment with and covering the porous carrier matrix, the top film portion having an opening formed through the thickness thereof which is in communication with the cavity of the housing and which is provided to receive the fluid sample containing an analyte or the one or more liquid reagents, the porous carrier matrix being disposed within the housing and situated in alignment with the top opening formed in the film portion to receive thereon the fluid sample or the one or more liquid reagents; and wherein the top side of the housing includes at least one recessed ledge, the at least one recessed ledge being situated adjacent to the recessed portion which receives the porous carrier matrix, the at least one recessed ledge having a top surface on which a portion of the underside surface of the top film portion rests. a top film portion, the top film portion being situated on the housing opposite the bottom side and in alignment with and covering the porous carrier matrix, the top film portion having an opening formed through the thickness thereof which is in communication with the cavity of the housing and which is provided to receive the fluid sample containing an analyte or the one or more liquid reagents, the porous carrier matrix being disposed within the housing and situated in alignment with the top opening formed in the film portion to receive thereon the fluid sample or the one or more liquid reagents; and wherein the top side of the housing includes at least one recessed ledge, the at least one recessed ledge being situated adjacent to the recessed portion which receives the porous carrier matrix, the at least one recessed ledge having a top surface on which a portion of the underside surface of the top film portion rests.