Tissue penetration

"Tissue penetration" is **not a molecule, receptor, or canonical therapeutic target**. Instead, it refers to the process or property by which substances (such as drugs, fixatives, or light) move into and through biological tissues. In pharmacology and drug development, tissue penetration describes how well a drug distributes from the bloodstream into various tissues—a key factor for efficacy in treating infections or tumors[3]. In histology and pathology, tissue penetration often refers to how well fixatives diffuse into tissue samples during preparation for microscopic analysis[4]. In photodynamic therapy and optical studies, "tissue penetration" can describe the depth that light of specific wavelengths can reach within biological tissues before being absorbed or scattered[1]. Because "tissue penetration" is a **property/process** rather than a discrete molecular entity (such as an enzyme, receptor, transporter), it does not have standard attributes like aliases/abbreviations/drug interactions/biomarkers/safety concerns associated with molecular targets. Therefore: - It should not be considered a therapeutic target. - There is something incorrect about listing "Tissue penetration" as if it were a molecule/receptor. If you are seeking information on molecules that influence tissue penetration (e.g., transporters affecting drug distribution), please specify further so that structured data can be provided for those actual targets.