One theory holds that because the tonsil has no afferent lymphatic
system, it is not unreasonable to believe that retrograde cervical spread can occur through the thoracic duct.
A comparative genomic hybridization study was ordered from the UCSF laboratory, but results were estimated to take 6-8 weeks, a period of time that could compromise afferent lymphatic
drainage from a scalp lesion and reduce the accuracy of the sentinel node biopsy.
Some afferent lymphatic
vessels drain to the deep inguinal nodes from the external iliac lymph glands (1), others feed back up into the lower abdominal tracts (12).
Schreiber et al proposed that because of the blockage of afferent lymphatic
drainage and resultant impaired antigen presentation, an edematous area becomes an "immunologically privileged site" predisposed to the development of these tumors.
In addition, the network of inguinal afferent lymphatic
vessels in the hindlimb was clearly observed in mice without skin pigmentation when hair follicles were at the later catagen and telogen and the melanin content was lower; however, those vessel structures could not be properly delineated in dark skin pigmented mice due to strong light absorption by melanin.