Tail Skin Grafts Research Articles

Skin Homograft Tolerance in Long-Lived Radiation Chimeras and Its Abolition by Injected Lymphoid Cells<xref ref-type="fn" rid="FN1">2</xref>

thal dose of x rays (870 r) and then received intravenous injections of mouse bone marrow cells obtained from genetically foreign normal donors (C3H strain). The mice that survived for 1 year or more after this treatnment were then challenged with tail-skin grafts to evaluate their immunological state. LAF/ sub 1/ and C3H-type skin grafts (corresponding to the host and the marrow donor strains, respectively) were accepted by almost all the recipients. BALB/c- or DBA/2-type skin grafts (foreign to both the host and marrow donor strains) were rejected. These long-lived mice, known to be radiation chimeras, are therefore capable of a homograft response, but are tolerant to skin grafts of host (LAF/sub 1/) or of marrow donor (C3H) geno-type. The tolerance to C3H skin grafts was abolished, and the C3H skin grafts were rejected 2 to 3 months after inoculation with lymphoid cells obtained from either normal or sensitized (anti-C3H) LAF/sub 1/ donors. Other chimeras, receiving injections of irradiated LAF/sub 1/ lymphoid tissue, maintained tolerance to the C3H skin grafts. To test for the presence of immunologically active C3H-type cells in these chimeras, cells from their lymphoid tissues were injected into sublethally irradiated (C3H x DBA/2)F/ sub 1/ hybrids, andmore » the signs of wasting and death known to follow the injection of parental strain C3H cells (but not LAF/sub 1/ cells) were observed. With this system, C3H lymphoid cells were present in the tolerant mice. In contrast, these cells were not present in the mice that were no longer tolerant to C3H grafts. (auth)« less

HISTOLYSIS AND REGENERATION OF ANURAN TAIL SKIN

1. Uniform-sized tail-skin grafts were secured from extreme dorsal, ventral, and one intermediate region of the tail and transplanted, autoplastically, to the backs of non-metamorphosing Rana catesbiana tadpoles. Artificial metamorphosis was then induced and the histolysis or reduction of the grafts studied. The median-source graft was invariably the first to undergo reduction followed in order by the ventral and dorsal, regardless of their antero-posterior transplantation sequence on the back.2. Similar grafts of tail-skin were transplanted, autoplastically, to the backs of non-metamorphosing larvæ, and artificial metamorphosis subsequently induced. At arbitrary stages of reduction the grafts were retransplanted, homoioplastically, to the backs of non-metamorphosing laræ and allowed to regenerate. The median graft was the first to complete regeneration, as determined by histological reconstitution; the ventral being the second and the dorsal third.3. The histolysis and regeneration of tail-skin always involves an orderly sequence of cellular changes. For both of these processes the sequence was determined as epidermis-dermis-subcutis.4. It is concluded that the histolytic sequence is due largely to a time differential in the onset of histolysis. The regenerative sequence is probably the result of a time differential in regenerative incipience.5. The physiological basis of these sequences is inherent in the tissues, and it is inferred that they may be determined or conditioned by different metabolic rates typical of each particular level.