Fine structure of the rat carotid body transplanted into the anterior chamber of the eye

Summary Rat carotid bodies transplanted into the anterior chamber of the eye were studied by electron microscopy. Chief and sustentacular cells and a few ganglion cells survived for 3 months and maintained cytological characteristics similar to those in the intact carotid body. The transplant contained many fenestrated capillaries. Chief cells at the periphery of the cell cluster had long cytoplasmic processes which projected into the stroma of the iris. The cell processes became incorporated into bundles containing nerve fibres, which were enveloped by a perineurial sheath. Three types of nerve fibres were identified in the explant. Type I and type II nerve fibres (presumptive cholinergic and adrenergic, respectively) were enclosed by sustentacular and satellite cells. Most of the nerve fibres were completely separated from chief cells and ganglion cells by sustentacular and satellite cells. A few nerve fibres made direct apposition to chief cells and ganglion cells, where some nerves were presynaptic to them. Type III nerve fibres derived from myelinated nerve fibres were also enclosed by sustentacular and satellite cells.     

Induction of GFAP production in human glioma lines grafted into the anterior chamber of the rat eye

Three established glial fibrillary acidic protein (GFAP)-negative cell lines from human gliomas were transplanted to the anterior chamber of the rat eye. Short-term survival was seen with all transplants. The cells expressed GFAP following transplantation. For comparison, 4 GFAP-positive cell lines were transplanted. With grafting of 5000 cells of any of 6 bipolar cell lines, the transplanted cells could be seen to develop multiple, slender processes reminiscent of mature astrocytes. When 50,000 cells were grafted, vascularized cell mats covering the corneae were seen. The induction of GFAP production and the phenotypic changes were interpreted as signs of differentiation induced by the new environment. All transplanted cells were rejected after 8 weeks.     

Retinal transplants into the anterior chamber of the rat eye

Developing retinas from 13-18-day fetuses and 2-day neonatal Long-Evans rats transplanted into the anterior chamber of adult eyes of the same or different strain (Lewis) survive and differentiate. Light and electron microscopic studies show that the transplants undergo histogenetic differentiation, resulting in the development of neurons and Müller glial cells and formation of nuclear and plexiform layers. Vascular connections develop between the host iris and the retinal transplant. Vessels and nerves, presumably of iridal origin, were seen on the surface of some transplants. Possible manifestations of graft rejection were monitored; signs of tissue rejection in transplants performed in the Long-Evans rats, an outbred strain, were rare and if present they were mild, at least during the survival periods of up to 91 days allowed in these experiments. Transplants into the eyes of Lewis rats were also well tolerated during the survival period. These observations indicate that retinal transplantation to the adult eye of a genetically different host can be successfully achieved and that both embryonic and perinatal retinas are suitable as donor tissue for ocular transplants. The procedure offers ample opportunities for the study of problems related to retinal plasticity.     

Effect of estrogens on neuronal development in nuclei of the tractus solitarius transplanted into the anterior chamber of the eye in rats

Laboratory of Experimental Morphology, Institute of Experimental Endocrinology, All-Union Endocrinologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 10, pp. 446–447, October, 1991.     

Immune privilege in the anterior chamber of the eye

Since the 19th century, it has been recognized that the anterior chamber of the eye permits the prolonged, and sometimes permanent, survival of foreign tissue and tumor grafts. It was initially believed that the absence of patent lymphatics draining the interior of the eye prevented antigens from reaching regional lymphoid tissues. However, sequestration of intraocular antigens alone cannot account for ocular immune privilege, and a clear picture is now emerging that a constellation of anatomical, physiological, and dynamic immunoregulatory factors contribute to ocular immune privilege. Ocular fluids contain a potpourri of immunosuppressive and immunoregulatory factors that suppress T-cell proliferation and secretion of proinflammatory cytokines. The interior of the eye is decorated with Fas ligand (CD95L), which induces apoptosis of infiltrating inflammatory cells. Antigens introduced into the eye induce a unique immune deviation in which TH1 responses, namely delayed-type hypersensitivity (DTH), are actively suppressed. Thus, ocular immune privilege is sustained by factors that suppress immune cell proliferation and purge immune cells that enter the eye and by a dynamic immunoregulatory process that suppresses antigen-specific DTH. Suppression of certain inflammatory responses is an important adaptation for preventing immune-mediated injury to ocular tissues that have little or no capacity to regenerate. Thus, immune privilege is a crucial adaptation for preserving vision.     

Implantation of thymic epithelial grafts into the anterior chamber of the murine eye: an experimental model for analyzing T-cell ontogeny

The object of this investigation was to establish whether the intracameral implantation of thymic epithelial grafts could be utilized as a valid in vivo experimental model for probing the possible mechanisms whereby the sympathetic innervation of the thymus influences thymocyte dynamics. Our findings suggest that deoxyguanosine-treated thymic epithelial grafts, implanted into the anterior chamber of the eye, were receptive to host lymphoid progenitor cells, capable of supporting T-lymphocyte maturational processes, and were able to export mature T cells to the secondary lymphoid organs of a previously T-cell deficient host. In addition, we verified that the number of lymphoid cells recovered from a thymic epithelial graft which had been implanted into an anterior chamber devoid of sympathetic nerve input was generally greater than the number of lymphoid cells recovered from a matched graft which had been implanted into an anterior chamber which had an intact sympathetic nerve supply. Based on the results of these studies, investigative efforts can now be directed at studying a number of important aspects associated with the relationship between T lymphocyte ontogeny and the sympathetic nervous system.     

Immunohistochemical studies on the development of tyrosine hydroxylase- and serotonin-immunoreactive neurons in fetal dorsal raphe tissue transplanted into the anterior eye chamber of adult rats

Pieces of tissue containing dorsal raphe nuclei of fetal rat brains were transplanted into the anterior eye chambers of adult rats. The differences between the developmental patterns of catecholaminergic and serotonergic neurons--especially the extension of their axonal processes--in the grafts were immunohistochemically examined using tyrosine hydroxylase (TH) and serotonin antisera. At an early stage after transplantation (3 days), TH-positive neurons appeared in grafts that had and had not been pretreated with a monoamine oxidase inhibitor (MAOI, Nialamide), while serotonin-positive neurons were demonstrated only in the grafts that had undergone MAOI pretreatment. Morphological differences in the growth pattern in the experimental milieu between the TH and serotonin neurons were also demonstrated: at this early stage, the somata of the TH neurons were multipolar and stellate shaped and possessed several distinct processes, while the serotonin neurons were ovoid shaped and lacked such processes. One week to 1 month after transplantation, the number of TH-positive fibers gradually increased, but their distribution was restricted to the area surrounding the cell bodies of the TH neurons in the graft. However, the processes of the serotonin neurons formed a dense plexus in the graft, and a small number of these fibers extended into the host iris 1 week after transplantation. By one month after the operation, the density of the serotonin fibers had gradually increased throughout the graft, and protruding serotonin fibers formed a network of varicose fibers in the host uveal tissue.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differentiation of neurons containing olfactory marker protein in adult rat olfactory epithelium transplanted to the anterior chamber of the eye

Olfactory marker protein is a cytoplasmic component unique to fully-differentiated olfactory sensory neurons. It has been proposed that expression of this protein occurs only if the neurons make synaptic contact with the central nervous system. In the present experiments, adult olfactory epithelium was transplanted as an autograft to the anterior chamber of the eye. This procedure destroys the mature sensory neurons, which are subsequently replaced by division and differentiation of stem cells. The newly-formed sensory neurons differentiate sufficiently to produce olfactory marker protein, without apparently contacting central nervous tissue.We conclude that contact with the central nervous system is not necessary for expression of olfactory marker protein.     

Induction of hepatic peroxisome proliferation in nonrodent species, including primates.

It is well established that the administration to rodents of a variety of structurally diverse chemicals possessing hypotriglyceridemic properties results in hepatomegaly, the induction of hepatic peroxisome (microbody) proliferation, and the development of hepatocellular carcinomas. Studies have led to the hypothesis that persistent proliferation of peroxisomes serves as an endogenous initiator of neoplastic transformation in liver by increasing the intracellular production of H2O2 by the peroxisomal oxidase(s). The objective of the present study was to determine whether hepatic peroxisome proliferation can be induced in cats, chickens, pigeons, and two species of monkeys (rhesus and cynomolgus). The hypolipidemic drug ciprofibrate (2-[4-(2,2-dichloro-cylopropyl)phenoxyl]2-methylpropionic acid) induced peroxisome proliferation in the livers of cats (dose, greater than 40 mg/kg body weight for 4 weeks); chickens (dose greater than 25 mg/kg body weight for 4 weeks); pigeons (300 mg/kg body weight for 3 weeks), rhesus monkeys (50 to 200 mg/kg body weight for 7 weeks) and cynomolgus monkeys (400 mg/kg body weight for 4 weeks). In all five species examined in this study, a marked but variable increase in the activities of peroxisomal catalase, carnitine acetyltransferase, heat-labile enoyl-CoA hydratase, and the fatty acid beta-oxidation system was observed. These results suggest that peroxisome proliferation can be induced in the livers of several species and that it is a dose-dependent but not a species-specific phenomenon.     

Fluid flow in the anterior chamber of a human eye

A simple model is presented to analyse fluid flow in the anteriorchamber of a human eye. It is shown that under normal conditionssuch flow inevitably occurs. The flow, whose reduced Reynoldsnumber is small, is viscosity dominated and is driven by buoyancyeffects which are present because of the temperature differencebetween the front and back of the anterior chamber. In casesof severe eye trauma or as a result of certain diseases andmedical conditions, particulate matter may be introduced intothe anterior chamber. The motion and distribution of such particlesis analysed and it is shown that the model is capable of predictingwell-established and observed features that may be present ina traumatized eye such as hyphemas, keratic precipitates, hypopyonsand Krukenberg spindles.