Evidence has been presented by several investigators that functional capacity of the kidney in the premature and young infant is lower than in older children and adults. Schoenthal (1) using urea clearance, McCance and Young (2) urea and inulin clearances, Barnett (3) inulin clearance, and

Immunological and biochemical studies of spontaneously metastasizing and nonmetastasizing rat mammary carcinomas and, their plasma membranes indicated that: (i) all spontaneously metastasizing tumors have little or no demonstrable glycocalyx, while all nonmetastasizing tumors have a thick glycocalyx; (ii) there is a direct relationship between the glycocalyx and immunogenicity, and an inverse relationship with the metastasizing capacity of tumor cells, properties which can be quantitated by levels of the plasma membrane marker enzyme 5'-nucleotidase (EC 3.1.3.5; 5'-ribonucleotide phosphohydrolase) activity; (iii) the absence of glycocalyx from the metastasizing tumor cell surface seems to result from its dissociation from plasma membranes, for solubilized cell surface antigen is readily found in the'blood of metastasizing tumor bearing rats, while there was no detectable tumor cell surface antigen in the blood of the nonmetastasizing tumor hosts tested; (iv) both metastasizing and nonmetastasizing mammary tumors appear to have a common soluble cell surface' antigen; (v) in addition to this common antigen, there is another membrane-bound antigen in the nonmetastasizing, immunogenic tumor cell surface which presumably is the tuinor specific transplantation antigen; and (vi) this antigen is immunobiologically unique, but seems to be immunochemically related to the common soluble antigen. It is postulated that the lack of an immunogenic coat and/or the presence of solubilized tumor cell surface antigen in the blood may provide an immune escape mechanism for tumor cells by interfering with cell-mediated immune response of tumor hosts, leading to their dissemination.In an earlier report one of us (U.K.) (1) described the induction of spontaneously metastasizing mammary carcinomas (MT) in a highly inbred strain of W/Fu female rats by feeding 3-methylcholanthrene in splenectomized, thymectomized, or both splenectomized and thymectomized hosts, and subsequently subjecting the developing tumors to "immunoselection" in vivo. Such tunmors maintained their metastasizing capacity in normal syngeneic rats generation after transplantation generation, indicating that the metastasizing capacity is an intrinsic property of tumor cells. It was further demonstrated that the metastasizing tumor cells were nonimmunogenic while the ordinary methylcholanthrene-induced nonmetastasizing mammary carcinomas in normal female rats were highly immunogenic, as tested by immunization of the hosts with an equal number of radiation-killed tumor cells, followed by a challenge with a counted number of live tumor cells.In order to study the relationship between tumor cell immunogenicity and metastasizing capacity, two spontaneously metastasizing, non-or weakly-immunogenic mammary carcinomas (SAIT-2A and TMT-50), induced in the manner described above, and a spontaneously metastasizing mammary carcinoma induced with 7,12-dimethylbenz(a)-anthracene in a BCG (bacille Calmette-Guerin) inoculated rat (BCG-MT) were selected. They were matched accord...

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