A neonatal munine neuroblastoma (NB) model has been developed in addition to a munine NB model for metastatic involvement. The S2OY NB cell line used was cloned from the A/Jax murine C1300 NB and was a gift from Dr. M. Nirenberg. Dose-response studies on adult male and female mice given s.c. injections showed no meaningful sex-re bated differences ineither theappearance or thegrowth rate of the tumors. No significant difference in tumor appearance or growth rate was observed between 10-day old

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... ups and adults. However, 24-to 48-hr-old pups (neo nates) inoculated with the same number of cells as the adults demonstrated a marked delay in tumor appearance. Neonates challenged with 5 x 10@cells showed a 75% reduction in tumor appearance when compared with their adult counterparts. An inoculum of 2 x 10@S2OY cells resulted in 100% of the adult mice developing tumors within 26 days, while none of the 24-to 48-hr-old pups had developed tumors more than 90 days postinjection. Corn panison of the s.c. and intradermal routes of injection of NB cells was made using 6-to 8-week-old male mice. Tumors developed at approximately the same rate. The intradermal tumors were removed at various stages of growth. Over 90% of the mice which underwent surgery and a similar percentage of the mice with intradermal tumors which did not have surgery subsequently developed metastases to the lymph nodes, liver, lungs, adrenals, heart, kidney, spleen, and abdominal area, sites commonly found to harbor met astatic lesions in cases of human NB. Metastases at these sites were not observed with s.c. inoculations.