Axial Organ Research Articles

In vitro effect of rabbit anti sea star lymphocyte serum on axial organ cells

The axial organ (AO-cells) of the sea star Asterias rubens is a primitive immune organ. The total population was fractionated or not into two populations: adherent (B-like) and non adherent (T-like) to nylon wool. Rabbit anti sea star lymphocyte serum induces the proliferation of axial organ cells. The T-like antiserum stimulates the T-like cells exclusively; the whole axial organ cell antiserum only stimulates the whole axial organ cell population.

Podocytes in the axial organ of echinoderms

The axial organ of two sea urchin genera, Echinometra and Eucidaris, has been analysed with the electron microscope. It is mainly built up by an extracoelomic tissue rich in various leucocytic cells and blood vessels lacking an endothelium. The axial sinus (axocoel) is located on the interior of the axial organ, and evaginations extend into this loosely constructed tissue. The epithelium of the axial sinus and its extensions are characterized by epitheliomuscular cells and abundant podocytes, which overlie the blood vessels. Since podocytes are the well known structural basis for ultrafiltration, it is postulated that this is a function of the axial organ at least in echinoids and asteroids.

Mitogens induced regulation of sea star axial organ cell humoral immune response in vitro

A specific anamnestic response occurs in the sea star, Asterias rubens after in vivo and in vitro stimulation of axial organ cells, with hapten-carrier conjugates. The effect of the mitogenic lectin Con.A on the in vitro production of antibody like factors is studied by means of a haemolytic assay. It appears that Con.A produces a modulating effect on the secondary in vitro response of sea star axial organ cells. I.O-Methyl-α-D-Mannopyranoside inhibits the modulating effect of Con.A in controls. On the other hand it appears clearly that LPS has no action on the synthesis and/or the activity of the “antibody-like” factors secreted by axial organ cells.

Production of an antibody-like factor in the sea star Asterias rubens: Role of the gastric haemal tufts

Cells from the axial organ (AO) of sea stars stimulated “in vivo” with TNP coupled to polyacrylamide beads and subsequently cultured “in vitro” were able to produce an antibody-like factor which induced the lysis of mammalian red cells sensitized with TNP. Three types of cells at least are involved in the production of the antibody-like factor. The addition of 2-mercapto-ethanol to the cultures including these 3 populations was essential but what is a novelty is the fact that cells from the gastric haemal tufts (G.H.T.), probably phagocytes, are able to replace it. Otherwise G.H.T. contain cells playing the role of nylon wool- non adherent AO cells or T like cells.

Immunocompetent cells in the starfish Asterias rubens. An ultrastructural study

Cells from the axial organ of the starfish Asterias rubens were fractionated into two populations, adherent and non-adherent to nylon wool. In both populations the ultrastructural study revealed the presence of cells resembling the lymphocytes of the vertebrates, as well as phagocytic, peroxidase positive cells. The lymphocyte-like cells in the non-adherent population (average diameter 4μ) have a high nucleo-cytoplasmatic ratio and are morphologically similar to Th lymphocytes while the adherent cells (average diameter 5.5 μ) are more similar to Bm lymphocytes. These observations are in line with the hypothesis that there exist, in the starfish, a primitive immune system with characteristics resembling those of the immune system of vertebrates.

Fine structure of the stalk of an isocrinid sea lily (Metacrinus rotundus) (Echinodermata, Crinoidea)

Sea lilies of the order Isocrinida (Metacrinus rotundus) were dredged from Sagami Bay, Japan, and their stalks were studied by transmission electron microscopy. New contributions to stalk histology are: an exact description of the different cell types in the stereom spaces; a demonstration of the haemal channel; and the discovery of (1) coelomic nerves, (2) collateral stalk nerves and (3) nerve tracts running with the aboral extension of the axial organ. Within the stalk, there is no structure derived from the axial sinus (=axocoel), and the widely accepted homology between the crinoid stalk and the larval asteroid stalk is thus open to serious question. The stalk has collagenous ligaments of two main types (intercolumnal ligaments and peripheral through-going ligaments); however, there are no central through-going ligaments comparable to those in stalks of larval feather stars and of bourgueticrinid sea lilies. The absence of muscles or other cells specialized for contractility indicates that the stalk of isocrinid sea lilies cannot bend actively. The cirri, which project from the stalk of M. rotundus, contain no muscle cells; however, the epithelial cells lining the oral and aboral coeloms of each cirrus contain a presumed contractile apparatus that is a bundle of 5 nm cytoplasmic filaments oriented parallel to each other and to the long axis of the cirrus.

NUTRIENT TRANSLOCATION IN THE SEA STAR: WHOLE-BODY AND MICROAUTORADIOGRAPHY AFTER INGESTION OF RADIOLABELED LEUCINE AND PALMITIC ACID.

Using the sea star, Asterias rubens, whole-body autoradiography has been employed to follow the distribution and the pathways of translocation of both soluble and tissue-incorporated label derived from orally administered 14C-labeled leucine or palmitic acid. Radioactivity remains localized predominantly in the stomach and pyloric caeca until sixteen days after ingestion. Labeling of the perivisceral coelomic cavity in regions close to the stomach shortly after ingestion points to initial displacement of ingested nutrients through the coelomic fluid and coelomocytes. After oral administration of labeled palmitic acid, distinct labeling of the gastric hemal tufts, axial organ, and aboral ring prior to labeling of the gonads also suggests the involvement of hemal tissue and surrounding perihemal coelomic sinuses in storage and translocation of substances needed for gamete nutrition. Microautoradiography of gonad tissue reveals a rapid labeling of the walls of the genital coelomic sinus, the ground substance of the genital hemal sinus, and, after prolonged incubation, the germinal epithelium. Little or no label is incorporated into the outer sac of the gonad wall. The results are discussed in terms of current knowledge on nutrient translocation in the sea star.

The Fine Structure of the Stalk of the Pentacrinoid Larva of a Feather Star, Comanthus japonica (Echinodermata: Crinoidea)

AbstractThe stalk of the pentacrinoid larva of a feather star (Comanthus japonica) is described for the first time by transmission electron microscopy. One end of the stalk bears the calyx and the other end is cemented to the substrate by attachment cement consisting of a meshwork of 5 nm filaments. The stalk is supported by a scries of skeletal ossicles pierced by a central canal: short intercolumnal ligaments connect adjacent skeletal ossicles and central through‐going ligaments run the length of the central canal. At the end of the stalk nearest the calyx, the chambered organ and the closely associated axial organ are histologically similar to those of adult crinoids. Presumed neurosecretory neurons are associated with the intercolumnal ligaments, and the following kinds of nerves run down the central canal: (1) a large stalk nerve in each of the five interradii; (2) smaller coelomic nerves in each of the five radii in association with the epithelium of tubular aboral extensions of the chambered organ; (3) a very small nerve associated with the aboral extension of the axial organ in the stalk axis. This axial organ extension is surrounded by a haemal channel. Because of the small size of the stalk, none of the nerves or the haemal channel were described in previous light microscopic studies. The discussion gives special attention to the controversial motility of the pentacrinoid stalk.

Specific immune response in the sea star Asterias rubens: Production of “antibody-like” factors

Axial organ cells from the sea star ( Asterias rubens) inoculated 7 days before with TNP- or FITC-haptenated PAA beads and subsequently stimulated in vitro with the same antigen, produced and released a specific, soluble “antibody-like” substance that induced lysis of haptenated sheep erythrocytes. Fresh normal rabbit or guinea pig serum was essential for the lysis, suggesting the participation of complement components. The factor was produced by the total population of axial organ cells but not by nylon-wool adherent (B-like) or nonadherent (T-like) cells. These results provide further evidence of the existence, in the sea star, of a primitive immune system with characteristics reminiscent of the immune system of vertebrates.

TRANSLOCATIVE FUNCTIONS OF THE ENIGMATIC ORGANS OF STARFISH—THE AXIAL ORGAN, HEMAL VESSELS, TIEDEMANN'S BODIES, AND RECTAL CAECA: AN AUTORADIOGRAPHIC STUDY

Starfish (Echinaster graminicolus) were fed C14-labeled clams or liquid glucoseamino acid medium, and subsequently examined as autoradiographic sections. Ingested tracer was first incorporated into the cardiac stomach and lower-middle digestive gland. By 8 to 12 hours, increasing amounts were located throughout the axial organ, aboral hemal ring, radial hemal strand, and mesenteric hemal vessel. Subsequently (22 to 48 hours), label progressed into the genital hemal connectives and the gonads, as well as the connective tissue-hemal plexus of the tube feet. C1early, hemal tissues, together with associated perihemal spaces, play major roles in the translocation of nutritive materials to the gonads and parts of the tube feet. These nutritive materials, however, may not come directly from the digestive system, which only has poorly developed hemal connections, but from coelomic sources.Also noted was a gradual build-up of labeled material in the rectal caeca, suggesting that these organs remove nutrients from circulating digestive fluid before its evacuation through the anus or mouth. In animals fed liquid medium, tracer rapidly appeared in all parts of the water vascular system. showing that inflow of sea water does occur through the madreporite. Intense, rapid uptake by the Tiedemann's bodies revealed that they must filter a portion of this inflow, possibly producing coelomic fluid for body turgor and stomach inflation.

Fine structure of the stalk of the bourgueticrinid sea lily Democrinus conifer (Echinodermata: Crinoidea)

Specimens of Democrinus conifer (A. H. Clark, 1909) dredged from about 280 m were fixed aboard ship for transmission electron microscopy. The most important new contributions to stalk histology are the following: an exact description of the different cell types of the stereom spaces; a demonstration of the haemal channel; description of the radial aggregations of cells in the central canal; discovery of coelomic nerves; and discovery of nerve tracts running in association with the aboral extension of the axial organ. The collagenous ligaments of the stalk are separated into three types anatomically (and possibly also functionally). The stalk contains no trace of an axial sinus derived during ontogeny from the anterior coelom (=axocoel). In the roots, the central canal contains a root nerve, but no extensions of the haemal channel or of the coelomic tubes; therefore, roots of bourgueticrinid sea lilies are not homologous to cirri of isocrinid sea lilies or feather stars. The chambered organ and axial organ of D. conifer closely resemble the same organs in feather stars that have previously been described by electron microscopy. The functional implications of our structural results are: (1) cells in the stereom space appear to be a major site of nutrient reserves, (2) the abundant cells with lipid-rich organelles could make the sea lily body more buoyant, and (3) the absence of muscles or other cells specialized for contractility indicates that the stalk of bourgueticrinid sea lilies cannot bend actively.

MLR-like reaction between axial organ cells from asterids

The uptake of [ 3H]thymidine by axial organ (AO) cells arising from two starfishes and mixed together, in a ratio of 50/50 was studied. Mixed leucocyte reaction (MLR) combinations gave a positive response at the fifth day of culture in about 20% of the tested combination (index: 1.8–6.7). No positive reaction was observed in an allogeneic system. More significant results seem to be obtained with the non-adherent nylon-wool subpopulation cells from the two species, rather than with the whole axial organ cells.

Spontaneous and induced cytotoxicity of axial organ cells from Asterias rubens (Asterid--echinoderm).

Spontaneously occurring cytotoxicity of starfish axial organ cells on target cells has been studied. It appears that in an allogeneic system no cytotoxic phenomenon occurs after 4 or 6 h of culture, whereas spontaneous cytotoxicity toward malignant vertebrate target cells is shown and reaches its maximum at 37 degrees C. In a certain way, the axial organ cell population includes cells, which may be compared with vertebrate natural killer cells. On the other hand, it must also be noted that axial organ cells are able to exert in a few cases, an induced cytotoxicity on MBL2 cells. This phenomenon appears at the end of the fourth day of culture.

Effect of in vivo inoculation of bacteria on the spontaneous cytotoxicity of axial organ cells from Asterias rubens

In vivo inoculation of heat-killed bacteria in the coelomic cavity of starfish induces an increase of spontaneous cytotoxicity developed by axial organ (an ancestral lymphoid organ) cells, phenomenon demonstrated by an in vitro [ 51Cr]-release assay. This observation corroborates the existence of a sophisticated immune system in the echinoderms, a first-rate model for phylogenic study of the immune response.

Properties of cell subpopulations of starfish axial organ: in vitro effect of pokeweed mitogen and evidence of lymphokine-like substances.

The in vitro effects of pokeweed mitogen (PWM) on axial organ (AO) cells of the echinoderm starfish Asteria rubens have been studied. PWM stimulates 3H-thymidine incorporation by the whole population of AO cells (index of stimulation 4-5). On the basis of surface adherence to nylon wool the AO cell population can be fractionated into adherent and non-adherent subpopulations. PWM strongly stimulates the non-adherent cells (index 14) but not the adherent cells (index 1.2-1.8). Specific soluble mediators obtained from stimulated non-adherent cells were able to stimulate the whole AO cell population but not the fractionated adherent or non-adherent cells.

Evidence of antibody-like substances secreted by axial organ cells of the starfish Asterias rubens

Evidence of antibody-like substances secreted by axial organ cells of the starfish, Asterias rubens, (invertebrate, echinoderm) was shown by the PFC method (plaque-forming cells).

In vitro effect of various mitogens on starfish ( Asterias rubens) axial organ cells

The effects of various mitogens on axial organ (AO) cells of the sea star have been studied. Pokeweed mitogen (PWM) stimulates [ 3H]thymidine incorporation by the whole population of axial organ cells of the sea star. This effect occurs 24 hr after the addition of PWM and is maximal at 40 μg/ml. In contrast, no stimulation is observed when coelomocytes are treated with PWM under the same conditions. No stimulation of the whole AO cell population is observed in the presence of Con A or LPS. However, the AO cell population can be divided, on the basis of surface adherence properties, into two subpopulations, adherent and nonadherent. Con A stimulates the nonadherent cells, but not the adherent cells: The stimulating effect is maximal 24 hr after addition of Con A and at 0.2–0.5 μg/ml. In contrast, LPS stimulates the adherent but not the nonadherent cells and the stimulating effect is maximal at 24 hr and at 45 μg/ml.

Correlation between the injection of specific proteins in starfishes and the appearance of binding sites for the same proteins in cell populations of their axial organ

Sea stars were injected with two different proteins (bovine serum albumin and whale myoglobin). Cell suspensions were prepared from the axial organ of injected and untreated animals. After exposure of these suspensions to soybean agglutinin (SBA), agglutinable and nonagglutinable cell subpopulations were obtained and compared as to their binding to fluorescent conjugates of the same proteins: FITC-serum albumin and FITC-myoglobin. The SBA-agglutinable subpopulation from injected animals showed a significantly higher number of membrane fluorescent cells than the nonagglutinable subpopulation. No significant membrane fluorescence was observed in the cell subpopulations obtained from untreated animals. The membrane fluorescence appeared mainly when the protein of the fluorescent conjugate was the same as that used for injecting the animal.

Fine structure of the axial complex of Sphaerechinus granularis (Lam.) (Echinodermata: Echinoidea).

Three regions of the axial complex in Sphaerechinus granularis can be distinguished: 1) The axial organ which protrudes from one side of the axial sinus; the sinus septum which separates the sinus from the body cavity and encloses the stone canal; the pulsating vessel which runs along the inside of the axial organ. 2) The blindly-ending terminal sinus in which the pulsating vessel broadens out to the contractile terminal process. 3) The ampulla of the stone canal which connects the axocoel and water vascular system and which opens out through the madreporite. A single-layered, monociliated coelomic epithelium surrounds all regions of the axial complex. This epithelium contains smooth muscle cells at the contractile areas. Canaliculi, surrounded by basal lamina, are formed through infolding of epithelia; they end blindly in the fluid- and connective tissue-matrix of the inner structures. The lacunae of the dorso-ventral mesentery connect the periesophageal and the perianal haemal ring with the axial organ. The axial organ contains many coelomocytes rich in pigment and granules. These coelomocytes are separated into compartments by elastic fibres. Phagocytosis of whole cells and transformational stages of coelomocytes suggest storage and degradation functions. An excretory function via the water vascular system is also suggested.

Separation of two different populations of axial organ cells of Asterias rubens by the use of lectins

Separation of two different populations of axial organ cells of Asterias rubens by the use of lectins