Daily injections of any one of several foreign serum proteins produced in rabbits functional and morphological alterations similar to those seen in acute, subacute, and chronic human glomerulonephritis. The critical factor determining whether a rabbit would develop renal disease and the type of disease developed was the amount of antibody the rabbit formed. Those responding with much antibody were likely to develop an acute, self-limited glomerulonephritis and to be subsequently immune to further renal damage. Those responding with antibody barely sufficient to neutralize the antigen injected developed subacute and chronic glomerulonephritis. In the circulation of the rabbits with chronic glomerulonephritis, there was a daily recurring antigen-antibody reaction in the region of near antigen excess to near antibody excess which presumably led to the disease. Antigen apparently in the form of antigen-antibody complexes was deposited along the renal capillary basement membranes coincident with the development of subacute and chronic glomerulonephritis. Once developed, the morphologic stigmata of chronic glomerulonephritis persisted even after injections of antigen were stopped. However, in milder instances the renal function recovered in part after stopping antigen. This experimental model has several implications: first, the renal injury is precipitated by antigens with no known affinity for, or immunologic relationship to, kidney; second, antigen antibody complexes localize in the kidney, apparently on the basis of non-immunologic factors, and may be an etiologic agent of renal injury; third, severe hypersensitivity disorders can be related specifically to relatively poor as well as to good antibody responses; and finally, the pathogenesis suggested here offers an alternative to that of nephrotoxic serum nephritis for the experimental approach to the study of human glomerulonephritis.

The pathogenesis of amyloidosis, usually considered a disease of disturbed metabolism or a degenerative process, remains unknown. Among several theories, that of an immunologic mechanism involving an antigen-antibody reaction has been postulated as a causative factor in the deposition of amyloid (1, 2). Although it has been rarely possible to test this postulation directiyl the so called "fluorescent antibody" technique of Coons et al. (31 4) does allow an approach to this problem since it makes possible an ~mmunologic analysis of histological sections. Recently, observations of increased gamma globulin in the glomeruli of a case of amyloidosis have been reported, using this technique (5). However the specific localization of gamma globulin in the amyloid deposits was not described.In the present study we have analyzed the amyloid deposits of secondary human and experimental amyloidosis in the rabbit for their homologous albumin and gamma globulin content, on the assumption that if an antigen-antibody reaction was responsible for the formation of amyloidl one might expect to find a specific concentration of gamma globulin within the deposits. Materials and MethodsPurified human plasma fraction II; 1 human plasma fraction V; ~ bovine plasma fraction II; a crystallized bovine plasma fraction V 4 and rabbit plasma fractions II and V ~ were used for animal immunizations. Anti human gamma globulin and albumin (anti HGG and anti HSA) and anti bovine gamma globulin and albumin (anti BGG and anti BSA) were obtained after injecting albino rabbits averaging 3~ kilos according to the following schedule: On

Maturation of the rat fetal thyroid was studied with the aid of 1131 and of fluorescence and electron microscopy. The I ~31 concentration of the fetal gland increased exponentially from day 17 to day 20 of gestation and was related to the weight of the fetus (and presumably the weight of the thyroid) and also to the quantity of 113t accumulated by the fetus. In the 17-day gland, thyroglobulin or immunologically similar material was sparsely present in the incipient lumens of some cell clusters. With maturation, this material increased and was also observed within follicular cells on days 18 to 19 of gestation. On day 20, the specifically reacting material was present in the follicular lumens and was absent from the cytoplasm of follicular epithelium. Ultrastructurally, the earliest thyroid cells examined were replete with all the organelles found in the more mature epithelium. No direct correlation could be made between the cytoplasmic structures and the presence of thyroglobulin, although the granular endoplasmic reticulum was most likely the organelle responsible for synthesis of thyroglobulin. Thyroglobulin or a precursor was found in fetal thyroid cells before measurable quantities of 113~ were concentrated and before cytoplasmic droplets appeared.Between day 18 and day 19 of gestation, the fetal thyroid of the rat acquires the capacity to concentrate easily measurable quantities of I t3t (1). Based on this property of isotope accumulation by the fetal thyroid, and with the aid of electron and fluorescence microscopy, the following study was designed to seek answers to three questions: First, does an intracellular organelle appear or become singularly prominent at the time the thyroid gland begins to trap iodide in high concentration? Second, during the maturation of the fetal thyroid, is it possible to localize the site of synthesis of specific thyroid protein, thyroglobulin? Third, is thyroglobulin or a precursor produced before the advent of iodide concentration by the gland? MATERIALS AND METHODSPregnant rats (Holtzman) with known mating times were injected subcutaneously on the 16th to 19th day of gestation a with 50 to 60 #c of 1131. 24 hours later the fetuses were removed from their etherized dams and their thyroids were visualized under a stereomicroscope. The glands to be processed for electron microscopy were flooded with 2 per cent osmium tetroxide in situ as quickly as possible after removal of the fetus from the uterus, usually within less than 1 minute. After freeing from the trachea, they were placed in 1 per cent buffered osmium tetroxide containing sucrose for 1 to 2 hours and then processed for Vestopal W embedding. Other fetal glands were embedded in a small piece of maternal 1 24 hours after a vaginal smear positive for sperm was counted as 1 day of gestation.

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We report a case of ectopic ectodermal structures in the ectocervix of a 51-year-old female. Sebaceous glands and numerous abnormal hair follicles were present in the stroma of an otherwise normal cervix.