1. L. Napolitano, J. Cell Biol.18, 663 (1963).
2. U. Smith, Anat. Rec.169, 97 (1971).
3. F.O. Adebonojo, Pediat. Res.9, 889 (1975).
4. W.J. Poznanski, I. Waheed and R. Van, Lab. Invest.29, 570 (1973).
5. R.L.R. Van, C.E. Bayliss and A.K. Roncari, J. clin. Invest.58, 669 (1976).