Ch. Grégoire

Coagulocyte Alterations in Clotting Hemolymph of Carausius morosus L

1. The structural changes in the coagulocytes of Carausius morosus during hemolymph coagulation in vitro have been studied under the PCM and in the TEM. 2. In agreement with former PCM observations on Carausius morosus, the coagulocytes are the only hemocytes to induce coagulation of the plasma. Immediately or after a few seconds upon withdrawal of the hemolymph, their structural changes consist of a considerable enlargement of the perinuclear cysterna and of direct ejection into the plasma of nuclear and cytoplasmic substances through microruptures of the cytoplasmic membrane. The other categories of hemocytes do not contribute to the plasma coagulation. Their structural alterations take place without breakage of the cytoplasmic membrane when the plasma reactions are already established. 4. These plasma reactions appear in the form of circular islands of granular material around the coagulocytes, of extension of the coagulum in the channels between the islands and of transformation of the clot into a network of threads. 5. As reported in other studies in the TEM, no specific organelle characteristic of the coagulocyte ultrastructure could be found in the coagulocytes of Carausius. 6. Owing to the absence of any specific structural criterion of identification, the results suggest that the functional difference between coagulocytes and the other categories of hemocytes as regards coagulation of the plasma might be caused in part by differences of permeability of the cell membranes.

Prism conchiolin of modern or fossil molluscan shells. An empire of protein paleization

Abstract 1. 1. While global nacre conchiolin shows in its composition the predominantly concentrations of four amino acids: glycine, alanine, serine and aspartic acid, global prism conchiolin shows a different pattern, characterized by two predominantly amino acids: glycine and aspartic acid. 2. 2. Prism conchiolin has been isolated from fossil shells of Pinna affinis (London, Clay, Lower Eocene) and Inoceramus sp. (Gault, Cretaceous). The comparison of modern and fossil prism conchiolins shows differences in the pattern of amino acid composition. The significance of these differences is discussed.

La trame protidique des nacres

When decalcified nacre is treated with ultrasonic waves, the organic matrix resolves itself into very thin lacelike protidic leaflets, which can be studied with the electron microscope. Controls have been made showing that the lacelike structure is not an artifact due to decalcification, fixation, treatment with ultrasonic waves, dessiccation or electronic bombardment. The ultramicroscopic structure of the lacelike mesh-work differs with the species. At this level, morphological features appear to characterize the three classes of Molluscs studied (Lamellibranchia, Gastropoda, Cephalopoda), and perhaps different genera within the same class. The extraction, by a borate buffer, of a water-soluble constituent of the protidic material does not appreciably modify the appearance of the structures studied. The extraction, by a sodium hydroxyde solution, of a second component, leaves a fibrous residue rich in alanine and glycine.

Gross and ultrastructural changes in coagulocytes of mole-cricket, Gryllotalpa sp. (Orthoptera: Gryllotalpidae) during in vitro hemolymph coagulation

Abstract The structural changes in the coagulocytes of Gryllotalpa sp. (Orthoptera) during in vitro hemolymph coagulation have been observed under the phase contrast (PCM) and transmission electron (TEM) microscopes. Among the extremely rapid changes, the most characteristic consisted of the development of multiple microruptures in the plasma membrane, accompanied by ejection of cytoplasmic material and simultaneous clotting reaction of the surrounding plasma. During these changes, the plasma membrane of the other categories of hemocytes (prohemocytes, plasmatocytes and granulocytes) remained intact. No distinct reaction appeared in the plasma surrounding these hemocytes. Occasional ultrastructural changes in these hemocytes occurred later when the plasma coagulation had already taken place. The results suggest that the coagulocytes play an exclusive part in initiating plasma coagulation. Differences in the reaction of the plasma membrane to foreign surfaces could explain the functional contrast between the active coagulocytes and the other hemocytes, at least at the beginning of coagulation of the hemolymph.

On ultrastructure of the trabeculae in the interlamellar membranes of nacre conchiolin of the Nautilus shell.

The ultrastructure of the interlamellar and intercrystalline membranes of nacre conchiolin of Nautilus has been studied on shadow-cast preparations and on ultrathin sections after various fixation and/or decalcification procedures. After immersion in osmium tetroxyde, glutaraldehyde, EDTA, ascorbic acid and CPC solutions, the nautiloid pattern of conchiolin structure (sturdy trabeculae, elongated fenestration) was observed in all samples. The representative ultrastructure of the sectioned trabeculae was composed of micro-meshworks. Microfibrils were not found. In contrast with the other substance, chromium sulphate produces a shrinkage of the nautiloid pattern into continuous rug-like membranes. In the sections, a distinct condensation of the micro-meshworks occurs at the periphery of both interlamellar and intercrystalline membranes. These observations are discussed namely in relation to the problem of structural identification of the EDTA soluble fraction of the nacre conchiolin.

Etude au microscope à contraste de phase du coagulocyte, du nuage granulaire et de la coagulation plasmatique dans le sang des Insectes

The type of coagulation of the hæmolymph observed in the present investigation shows a striking analogy with the process of coagulation as described in Crustacean blood, especially with the first stage of Type C ofTaits classification, associated with the presence of explosive corpuscles.