Cellular cooperation in hapten-carrier responses in the newt, Triturus viridescens

Heterologous erythrocyte responses in the three hematopoietic organs, spleen, liver and kidney, were studied in the American Common Newt, Triturus (Diemictylus) viridescens. These responses were measured by immunocytoadherence. Horse (HRBC) and sheep (SRBC) red cells were used as immunogens. Background and response values to HRBC were consistent in all three organs. Activity levels and their kinetics were greater in spleen than in liver or kidney. Anti-SRBC activity levels proved to be too variable and as a consequence HRBC's were used in subsequent studies. Secondary responses in the newt showed modest increases in the spleen, a decrease in liver activity levels and a proportionately large (5×) increase within kidney. While splenectomy prior to immunization did not effect primary response activity in liver and kidney, it caused a three-fold enhancement of the usual loss of activity in secondary responses within liver. Kidney secondary response levels were unaffected by prior splenectomy. Spleen-liver lymphoid traffic may be involved in anamnestic responses in the newt.The main question had to do with whether one could demonstrate cellular cooperation in immune responses in so primitive a vertebrate. Chicken (CRBC) and toad (TRBC) red cells were used as carriers for the hapten trinitrophenol (TNP). Pre-immunization with the carrier immunogen led to the development of rosette forming cells (RFC) specific for the hapten in spleen, liver, and kidney after challenge with the TNP on the same carrier. Injection of the TNP carrier alone or pre-immunization with a different carrier caused no TNP-specific RFC's to be generated. The anti-TNP responses were assayed with HRBC and TNP-HRBC. Prior treatment with TNP-HSA (human serum albumin), before TNP-HRBC assay, blocked the RFC with TNP-HRBC and helped to establish the specificity of the hapten-specific RFC's. These kinds of immune responses in the newt require at least two cooperating cellular populations. Cellular cooperation may have been an early phylogenetic feature of immune responses.     

Polymorphism of Trypanosoma cruzi in the blood of a vertebrate host

Tetramorphism of trypomastigote forms has been discovered in the blood stream of mice infected with Trypanosoma cruzi, that is C slender, C middle, S slender, S middle and forms intermediate between C and S. Regular changes of forms have been observed in the course of the infection. In the middle of the process, at the moment of maximum destruction of parasites affected by immunosystems of the host, C-forms prevailing on the whole substantially give place to S-forms, slender variants being replaced by middle ones within each of them. Polymorphism in the bloodstream of the vertebrate host is the general property of all trypanosomes, with their common biological value: immunological adaptation to parasitism in the blood and preadaptation to the continuation of the life cycle in the invertebrate host.     

The ultrastructure of the layers enveloping yolk-forming oocytes from Triturus viridescens

Conclusion The peripheral membranous and extracellular layers of oocytes at the onset of yolk formation were studied by electron microscopy. It was shown that three cellular layers are present at this time. The outer or surface epithelium contains typical squamous cells. The middle or theca is the connective tissue layer which contains fibroblasts, blood vessels, and collagen fibers. The inner or follicular epithelium proper consists of compactly arrayed follicle cells that have distinct cell boundaries. Two extracellular layers were observed, a coarse granular homogeneous layer and a dense zona radiata. Macrovilli (0.2 in diameter), extensions from the follicle cells, project through the extracellular layers into the peripheral cytoplasm while more numerous microvilli (0.1 in diameter) project up to the dense matrix of the zona radiata. The plasmolemma separating the peripheral cytoplasm from the follicle cells is completely irregular; it forms microvilli. The relations of the enveloping layers as seen with both light and electron microscopes are discussed.This investigation was supported by a Public Health Service research grant (5803-C3) and research career program award (K-3-5356) from the Division of General Medical Sciences.     

The influence of the nerve on lower jaw regeneration in the adult newt, Triturus viridescens

The present investigation was undertaken in an attempt to determine the role played by the nerve in the regeneration of the lower jaw of the adult newt, Triturus viridescens. The results indicated that the number of nerve fibers normally available at the amputation surface was very low compared with that of the newt forelimb. Furthermore, denervation of the lower jaw reduced the number of nerve fibers available to an extremely low level and maintained the number at a low level for up to four weeks without intervening redenervations. The regenerative events in the denervated and amputated lower jaws were indistinguishable histologically from those in amputated jaws having normal innervation. This presented an apparent exception to the general rule that regeneration of external body parts is dependent on the nerve. Several possible explanations are proposed by which this apparent exception might be explained. The process following amputation might be an exaggerated form of wound healing and tissue regeneration which can occur in the absence of nerves. The tissues of the lower jaw might be more sensitive to the influence of those nerve fibers present. The nerve fibers themselves might be qualitatively different and thus exert a greater influence on the tissues.     

The fine structure of the pigment epithelium and photoreceptor cells of the newt,Triturus viridescens dorsalis (Rafinesque)

The morphology of the retinal pigment epithelium and photoreceptor cells has been studied in the common newt Triturus viridescens dorsalis by light, conventional transmission and scanning electron microscopy. The pigment epithelium is formed by a single layer of low rectangular cells, separated by a multilayered membrane (Bruch's membrane) from the vessels of the choriocapillaris. The scleral border of the pigment epithelium is highly infolded and each epithelial cell contains smooth endoplasmic reticulum, myeloid bodies, mitochondria, lysosomes, phagosomes and an oval nucleus. Inner, pigment laden, epithelial processes surround the photoreceptor outer and inner segments. The three retinal photoreceptor types, rods, single cones and double cones, differ in both external and internal appearance. The newt, rod, outer segments appear denser than the cones in both light and electron micrographs, due to a greater number of rod lamellae per unit distance of outer segment and to the presence of electron dense intralamellar bands. The rod outer segments possess deep incisures in the lamellae while the cone lamellae lack incisures. Both rod and cone outer segments are supported by a peripheral array of dendritic processes containing longitudinal filaments which originate in the inner segment. The inner segment mitochondria, forming the rod ellipsoid, arelong and narrow while those in the cone are spherical to oval in shape. The inner segments of all three receptor cell types also contain a glycogen-filled paraboloid and a myoid region, just outside the nucleus, rich in both rough and smooth endoplasmic reticulum. The elongate, cylindrical nuclei differ in density. The rod nuclei are denser than those of the cones, contain clumped chromatin and usually extend further vitreally. Similarly, the cytoplasm of the rod synaptic terminal is denser than its cone counterpart and contains synaptic vesicles almost twice as large as those of the cones. Photoreceptor synapses in rods and cones are established by both superficial and invaginated contacts with bipolar or horizontal cells.