Perineural angiogenesis in mice bearing subcutaneous tumours.

Cells of myeloma or fibrosarcoma were inoculated s.c. into BALB/c mice. Intact skins and tissue sections from animals killed at periodic intervals after inoculation of tumor cells were examined macroscopically and microscopically. The development of new blood vessels, probably involved in vascularization of the tumor, was observed around the nerves adjacent to the deposit of tumour cells. This occurred 5 days after inoculation of cells and before the tumour had a mean diameter of less than 1 mm. Lesser degrees of "perineural angiogenesis" were noted after s.c. inoculation of mineral oil, Freund's complete adjuvant or implantation of intact spleen, but none was observed with killed tumour cells.