A new definition about the relationship of intercellular fluid in the brain with the mandibular and parotid lymph nodes

This study was carried out to reveal the relationship of the brain with both the mandibular lymph node (MLN) and parotid lymph node (PLN) by the hyperspectral fluorescence imaging techniques of Qdot 800 (QD) nanoparticles using in vivo. This relationship of the brain with both lymph nodes offers the preliminary morphological definition of lymphatic drainage. QD was injected into the left parietal brain lobe of each rat at a depth of 2.50 mm. In 65% of the rats that were imaged in vivo, signals were received first from the right MLN and PLN, and then from the left MLN and PLN. In contrast, in two female rats, the first signal was received from the right PLN. There was no difference between the female and male rats overall. The most noteworthy finding of this study was that the tracer injected into the left parietal lobe reached the right mandibular and parotid lymph nodules earlier. This result indicates a different and unknown pathway in the brain that communicates with the lymph nodes. Moreover, this study shows that these lymph nodes pathways can be used in the treatment of diseases such as brain trauma, cerebral edema, and Alzheimer's disease (AD). There is not much known about the lymphatic circulatory system in the brain. The process in which the solutions pass in the brain parenchyma via the interstitial space has not been fully understood up to now. The glymphatic system is a waste‐cleaning system using an extraordinary perivascular channel system, made of astroglial cells, to expel the dissolvable metabolites and proteins out of the central nervous system (CNS). The glymphatic system is a useful waste expulsion way for the CNS. Astonishingly, the glymphatic system works basically during sleep and is generally impaired during wakefulness. In the upper row, it is seen that Qdot 800 (QD) nanoparticles injected into the left parietal lobe of the brain are located between the layers of the parenchymal vessels. The images below show the presence of QD nanoparticles in the parotid and mandibular lymph nodes of QD for the first time by energy dispersive X‐ray (EDX) analysis. No literature on EDX mapping was found in the literature search.