Homotransplantation of suprarenal glands from prepuberal rats into the eyes of adult hosts

The transplantation of normal tissues: with special reference to auto- and homotransplants of thyroid and spleen in the anterior chamber of the eye, and subcutaneously, in guinea-pigs

The transplantation of tissues raises many yet unsolved problems of fundamental interest, and is of potentially great clinical importance, especially in endocrinology. The present investigation is concerned with three main problems: the immunological reactions associated with the growth of homografts in the anterior chamber of the eye and subcutaneously; the role of the reticulo-endothelial system in the resistance to homografts; and the applicability of Halsted’s principle to auto- and homografts of endocrine tissue, and the mechanism involved. Four groups of experiments are described. In group I, a preliminary study of auto- and homografts of thyroid in the guinea-pig, it is shown that, if a total thyroid deficiency is produced in the host, autografts are uniformly successful both in the anterior chamber and subcutaneously, whereas homografts are usually successful in the anterior chamber but rarely so when made subcutaneously. Halsted’s principle holds good for anterior chamber grafts whether auto- or homografts, i.e. the proportion of successful grafts increases pari passu with the degree of thyroid deficiency produced in the host, but appears to be less applicable to subcutaneous autografts. Some light is thrown on the mechanism of Halsted’s principle by the observation that successful anterior chamber grafts can be obtained in non-thyroidectomized hosts if injections of pituitary thyrotrophic hormone are given. The experiments of group II are concerned with the immunological phenomena relating to thyroid homografts. It is shown that a subcutaneous homograft of thyroid in the guinea-pig is demonstrably antigenic and the same is true of a homograft in the anterior chamber provided this is undergoing destruction. The state of immunity induced is general and extends to the anterior chamber. The existence of a state of immunity induced by a homograft is shown by the diminished chance of a subsequent homograft ‘taking’, but ‘immunization’ (by means of a subcutaneous graft) of an animal which already has a homograft established in the anterior chamber does not appear to modify the behaviour of the latter. In group III it is shown that a homograft transferred after some months from the anterior chamber to a subcutaneous site is more likely to survive than a primary subcutaneous homograft. It thus appears that when a homograft is established in the anterior chamber for a sufficiently long time a process of adaptation occurs as between graft and host. The experiments of group IV relate to the behaviour of auto- and homografts of spleen in the anterior chamber, and of simultaneous thyroid and splenic grafts. It is shown that the chances of success of a thyroid homograft in the anterior chamber are greatly reduced if the latter is provided with reticulo-endothelial tissue in the shape of a simultaneous autograft of spleen, but that a simultaneous homograft of spleen from the same donor has little or no deleterious effect. The mechanism of this phenomenon has not been fully elucidated but would appear to be either cellular, humoral or a combination of the two.

Study of ACTH-immunoreactive cells after transplantation of neonatal adrenal glands into adult adrenalectomized rats

The morphological and morphometrical features of the ACTH-immunoreactive cells of the anterior pituitary gland were compared between adult rats with intact adrenals, adult rats without adrenals, and adult rats with regenerated adrenocortical nodules. The removal of the adrenal glands produced a great increase in the number and size of the cytoplasmic processes of the ACTH-immunoreactive cells that sometimes establish contact with those of the neighbouring immunoreactive cells. In addition, in this experimental group, the ACTH-cell percentage and the mean cell, cytoplasmic, and nuclear areas were greatly increased in comparison with those found in control animals. Several regenerated adrenocortical nodules were observed in the small-bowel segment of rats transplanted with neonatal adrenal glands. The percentage and morphometrical values of the pituitary ACTH-reactive cells of this experimental group, although slightly increased relative to the rats with intact adrenals, were greatly decreased in relation to those of the adrenalectomized animals. It is concluded that the neonatal adrenal tissue regenerated after its transplantation into adult rats, a process that modified the percentage, the morphological characteristics, and the morphometrical values of the ACTH-immunoreactive cells of the adrenalectomized rats.

Autotransplantation of the adrenal cortex: a morphological and autoradiographic study

A morphological and autoradiographic study was made of the adrenal gland of adult male rats after autotransplantation. The simple technique involved placement of pieces of the adrenal gland in a dorsal plane between the skin and muscle. Animals for morphological studies were sacrificed at 2, 3, 4, 7, 15, 30, 90, and 180 days after autotransplantation. Those for autoradiographic studies were sacrificed at 2, 3, 7, and 15 days after autotransplantation, with 3H-thymidine being administered intraperitoneally 2 h before sacrifice. Sham-operated animals were used as controls. The majority of glandular adrenal cells suffered necrosis in the first days (2 and 3) after autotransplantation. Up until 15 days and after revascularization, morphological features of the cells were compatible with protein synthesis exhibiting a developed RER, scarce SER, and mitochondria with tubular and lamellar cristae. These data may correspond to a proliferative phase of glandular cells. At day 15, cells showed morphological signs of steroidogenic activity (mitochondria with vesicular cristae, increase of SER), and at day 30, an increased number of microvilli were seen. Between 30 and 90 days zonation of the adrenal was evident with glomerulosa, fasciculata, and reticular zones readily apparent. The quantitative analysis showed a significant increase of the volumetric density of mitochondria and microvilli between the days 7 and 30. Autoradiographic studies showed an intense labelling of fibroblast-like cells at days 2 and 3 and of glandular cells at days 7 and 15, which was confirmed by the quantitative studies. Corticosterone in autotransplanted animals decreased during the first 15 days, but after 30 days the values were similar to controls. The model reported here seems to be good for study of the regeneration of the adrenal gland and can be a simple, useful, and reproducible method for adrenal transplantation.