Intrauterine grafting in rats of autologous and homologous adult rat skin

Effect of eosinophil-degranulating estrogens on spleen eosinophils and white pulp/red pulp ratio

A role for eosinophils in the immune reaction has not been yet established. Considering that these leukocytes accumulate in lymphoid organs under glucocorticoid stimulation, we explored the possibility that they participate in the depression of immune reactions induced by these hormones and that they degranulate to exert this action. In this context, we investigated the dose effect of three estrogens on the number and degranulation of spleen red pulp eosinophils and on the percentage of spleen cross sectional area comprising white pulp. Estradiol-17 beta or 4 (OH) estradiol-17 beta increased red pulp eosinophils at low doses: 2 (OH) estradiol-17 beta increased them at a very high dose. The three estrogens degranulated the spleen eosinophils and decreased the lymphocyte containing spleen white pulp. We propose that the decrease in white pulp is a response mediated by agents released from degranulating eosinophils under the action of estrogen. Consequently, both estrogen-induced eosinophil degranulation and estrogen-induced increase in red pulp eosinophil numbers are conditions contributing to a decrease in white pulp volume. All above evidence supports the hypothesis that eosinophils are involved in immunoregulation by diminishing the number of lymphocytes contained in lymphoid organs.

The effect of progesterone, oestrogens and hydrocortisone on the mitogenic response of lymphocytes to phytohaemagglutinin in pregnant and non-pregnant women

The mitogenic response to phytohaemagglutinin of lymphocytes from women in the third trimester of pregnancy is not inhibited by progesterone, oestriol or oestradiol even at much greater than normal physiological levels. There was no difference in the response of lymphocytes from pregnant or non-pregnant women. Inhibition in the mitogenic response to phytohaemagglutinin was achieved with hydrocortisone but not at the physiological levels found in pregnancy. The results from this in vitro study would not support the view that the level of steroid hormones in pregnancy significantly affects the immunological status of the mothers.

The immunobiology of placentation

A review of the current theories on the nature of the placental allograft and the evolution of placentation in the presence of a cellular immune response highlights the inability of current hypotheses to explain the success of both invertebrate and vertebrate placentation. Only one theory -- "the anatomical separation of the fetus from the mother" -- appears relevant. How this separation might develop during implantation is discussed.

Uterine skin grafts and fertility control in the rat

Autologous intrauterine skin grafting was studied as a method of fertility control in the rat. Skin taken from the ear was grafted onto the right horn in 52 rats. All skin grafts "took" and developed into one of three forms: (1) replacement of endometrium over a wide area, (2) polypoid formations, or (3) skin bridges. Curettage before the skin grafting did not affect the "take" or subsequent course of the graft. After mating, no pregnancy occurred in skin-grafted horns, whereas control horns behaved like those in control rats. Results obtained in rat uteri indicate another approach to the treatment of uterine bleeding and possibly to contraception.

Implantation, transplantation, and epithelial-mesenchymal relationships in the rat uterus

Free tail skin grafts or suspensions of viable epidermal cells have been placed in the atraumatized uterus of isologous rat hosts and allowed to "implant" of their own accord to study the possible uniqueness of this site for other than nature's transplants, i.e. conceptuses, and its response to unnatural grafts. Despite the presence of an intact endometrial epithelium, free skin grafts heal-in rapidly, provided that a state of estrogen excess is established at the time of transplantation. In the absence of estrogen most of the grafts failed to implant. Once established, the grafts survive indefinitely without further estrogen. However, if at any stage a state of continual estrus is established, skin epidermis migrates centrifugally from the graft perimeter invasively replacing the native uterine epithelium. The results of an analysis of the modus operandi of this estrogen-facilitated epidermal migration in utero sustain the view that the hormone acts upon the uterine stroma rather than upon the epidermal cells. When grafts of lingual mucosa or vaginal "skin" were placed in the uteri of rats maintained in chronic estrus, migration of epidermis took place even more vigorously than from tail skin. These epithelia conserved their distinctive histologic specificities indefinitely when growing as heterotypic recombinants on the alien mesenchymal stroma of the uterus. Monodisperse suspensions of epidermal cells appear to "implant" and establish small epidermal plaques in the uterus only at sites predestined to accept conceptuses. That the endocrinologic parameters for the establishment of skin grafts in the uterus are similar to those for blastocysts is suggested by the finding that both kinds of graft can become established in the same uterine horn in the absence of exogenous hormones.