Bioreactor and/or mixing container, comprising: - an outer wall , which is designed to enclose a medium; and - a spectroscopic cell , which is arranged in the outer wall , wherein the spectroscopic cell comprises: - a first housing part and a second housing part , which are arranged opposite each other, wherein the first housing part is arranged on an outside of the bioreactor container and the second housing part is arranged in the interior of the bioreactor container, wherein on the opposing sides of the first housing part and of the second housing part one or more connection areas are formed, which connect the first housing part and the second housing part to each other and wherein a hollow space (H) is formed between the first housing part and the second housing part , wherein the second housing part has a plurality of openings , which provide a fluid connection between the interior of the bioreactor container and the hollow space (H) and wherein the plurality of openings are spaced apart from one another by webs ; - a bioreactor connection area , which is formed on the periphery of the spectroscopic cell and by means of which the spectroscopic cell is connected to the outer wall of the bioreactor container; - a first optical area and a second optical area , which are arranged in the hollow space (H), wherein the first optical area is arranged on the second housing part and the second optical area is arranged opposite the first optical area , wherein the first optical area and the second optical area can be set to at least two different distances to each other; and - a specimen space chamber , which is located between the first optical area and the second optical area , wherein at a measuring distance of the at least two different distances, the specimen space can be filled with the medium through the plurality of openings , and wherein for the purposes of a spectroscopic measurement at least one optical area has a light-transmissive embodiment. - an outer wall , which is designed to enclose a medium; and - a spectroscopic cell , which is arranged in the outer wall , wherein the spectroscopic cell comprises: - a first housing part and a second housing part , which are arranged opposite each other, wherein the first housing part is arranged on an outside of the bioreactor container and the second housing part is arranged in the interior of the bioreactor container, wherein on the opposing sides of the first housing part and of the second housing part one or more connection areas are formed, which connect the first housing part and the second housing part to each other and wherein a hollow space (H) is formed between the first housing part and the second housing part , wherein the second housing part has a plurality of openings , which provide a fluid connection between the interior of the bioreactor container and the hollow space (H) and wherein the plurality of openings are spaced apart from one another by webs ; - a bioreactor connection area , which is formed on the periphery of the spectroscopic cell and by means of which the spectroscopic cell is connected to the outer wall of the bioreactor container; - a first optical area and a second optical area , which are arranged in the hollow space (H), wherein the first optical area is arranged on the second housing part and the second optical area is arranged opposite the first optical area , wherein the first optical area and the second optical area can be set to at least two different distances to each other; and - a specimen space chamber , which is located between the first optical area and the second optical area , wherein at a measuring distance of the at least two different distances, the specimen space can be filled with the medium through the plurality of openings , and wherein for the purposes of a spectroscopic measurement at least one optical area has a light-transmissive embodiment. <EOS>