Etude au Microscope Electronique du CiliéPseudomicrothorax dubius Maupas

SYNOPSIS. Ciliates of the genus Pseudomicrothorax present, at the ultrastructural level, some remarkable peculiarities from the points of view of both cytology and taxonomy. The trichocysts have 4 apical blades which are characteristic of the family Microthoracidae; the curious subcuticular membrane is found in the Microthoracidae and, admittedly less typically, in the Nassulidae; the cytopharyngeal armature is exactly comparable to that of the Nassulidae. These facts, like those of Thompson and Corliss on the organization of the oral ciliates, show—as suggested by Corliss–that the taxonomic position of the genus Pseudomicrothorax throws light on certain stages of the evolution of the Ciliata.     

Ultrastructures Corticales du Cilié Holotriche Drepanomonas dentata Fresenius, 1858

SYNOPSIS. A study of the fine structure of the cortex of the ciliate Drepanomonas dentata revealed that it has a double cuticular membrane with a lamina corticalis and fibrous trichocysts with a quadripartite apical point. These characters warrant its assignment to the family Microthoraddae.     

Caractéristiques Ultrastructurales du Cortex et des Membranelles du CiliéEspejoia mucicola (Oligohymenophora, Hymenostomata, Tetrahymenina)

RESUME. L' étude détaillée du cortex et des organelles buccaux adoraux d' Espejoia montre que ce Cilié possède une organisation ultrastructurale comparable à celle des Tétrahyméniens. Tout en restant conforme au plan général d'organisation de ces derniers, des variations spécifiques décelées tant au niveau du cortex d'une part, que des membranelles, d'autre part, font ressortir des affinités trés marquées pour le genre Glaucoma et autres Ciliés voisins. En conséquence, en nous appuyant en outre sur les données récentes de la morphogenèse, nous confirmons la position d' E. mucicola parmi les Tetrahymenina, dans la famille des Glaucomidae.     

Morphogenèse de Régénération chez le CiliéCondylostoma magnum (Spiegel): Etude ultrastructurale

SYNOPSIS Cortical events occurring in the course of regeneration in Condylostoma magnum (Spiegel) were studied by electron microscopy. The zone of regeneration is very rich in vacuoles and small vesicles formed from the plasma membrane. Multiplication of kinetosomes starts on the left side of kineties in the V-shaped left ventral area, normally implicated in stomatogenesis, at the level of the anterior kinetosomes of the somatic pairs. The proliferation proceeds by the appearance of young kinetosomes most often orthogonal to the old ones. This process of multiplication is very rapid and terminates in the formation of an “anarchic field” in which one observes that: (a) the newly formed kinetosomes do not possess all the associated postciliary fibers; and (b) when these fibers are detected, the kinetosomes are not in the same orientation. Differentiation of the adoral organelles takes place in the left part of the field (left primordium) by an alignment of the kinetosomes into 2 rows for each organelle (oriented perpendicularly to the antero-posterior axis of the ciliate), of which only one has the postciliary fibers. Ciliatogenesis occurs in numerous kinetosomes of the anarchic field; in certain kinetosomes it is achieved at the onset of their arrangement into organelles and is concomitant with growth of the nematodesmata. The 3rd (anterior) row of the organelles, the interkinetosomal desmata, and connections among neighboring organelles appear only secondarily. Differentiation of the paroral cilia occurs later. It takes place in the interior of the primordium, whose organization is primarily anarchic, and is accompanied by a progressive resorption of the major part of the newly formed kineties. Numerous kinetosomes of the right field have the associated postciliary fibers, which are not found at the level of the regenerated “polystichomonad” (paroral organization characteristic of C. magnum). Finally, the formation of new kinetosomes within a somatic kinety at the time of its elongation is described.     

Activité Cellulolytique des Ciliés Entodiniomorphes

RESUME. Dans nos travaux antérieurs, nous avons observé dans les cultures in vitro que la disparition de la cellulose (languettes de papier filtre) est 2 fois plus grande lorsque les 2 micropopulations, Entodinium et bactéries, sont présentes que lorsque les bactéries sont seules ou en présence de cellules mortes de ciliés. Les filtrats des broyats cellulaires des ciliés entodiniomorphes de la panse des ruminants et du caecum des équidés possèdent une activité cellulolytique indépendante des bactéries endocellulaires. Il s'agit essentiellement d'une polyglucosidase (Cx) qui dégrade les dérivés de la cellulose native. On observe également une légère activité cellulolytique C₁ sur la cellulose native.
SYNOPSIS. We have observed previously that twice as much cellulose disappears from cultures containing both Entodinium and bacteria than from those which contain bacteria alone or with dead ciliates. Filtrates of cell-free homogenates of the entodiniomorphid ciliates from sheep rumen and horse cecum have a hydrolytic effect upon cellulose, hydrolytic activity being independent of the intracellular bacteria. The predominant enzyme involved in the reaction is a polyglucosidase (Cx) which acts upon derivatives of native cellulose. Low level activity of enzyme C₁, which attacks native cellulose, also is found in the filtrate.     

Etude du cycle reproducteur du goujon, Gobio gobio L. 2 Variations saisonnières dans l'histologie des testicules

Study on the reproductive cycle of the gudgeon, Gobio gobio L. Part 2 Monthly samplings of male gudgeons, Gobio gobio L. reared in ponds were carried out to study the spermatogenesis of this cyprinid during an entire annual cycle. Together with macroscopic parameters (GSI, condition coefficients, K and K1, nuptial tubercles) the cytologic characteristics of the testis maturation were analysed. The relationship between environmental conditions and spermatogenesis was also examined. The spermatogenetic cycle of G. gobio was divided in two separate periods: a) from October until March, during which only the spermatogonia (SgA and SgB) were present, and b) a stage of active transformation, from April until August, when all the 5 testicular cells (SgA, SgB, Scyt, Spd, Spz) were determined. Dynamic aspects of spermatogenesis were also investigated by an estimation of the proportion of each cellular stage. Spermiation, by abdominal pressure, occurred from mid-April to end of July.     

Etude ultrastructurale des corps ultimobranchiaux du poulet

Résumé Les corps ultimobranchiaux du poulet sont constitués de cordons glandulaires composés de cellules principales sécrétrices et de cellules bordantes. D'après le diamètre des grains de sécrétion, on peut distinguer au moins deux types de cellules principales, les cellules à petits grains (autour de 200 m) et les cellules à gros grains (250–300 m). Cette variation morphologique n'implique pas obligatoirement des sécrétions hormonales différentes. Les grains de sécrétion ne sont pas conservés par la fixation osmiée simple; ils se comportent sur ce point comme ceux des cellules parafolliculaires thyroïdiennes du mammifère dont les corps ultimobranchiaux représentent probablement les homologues fonctionnels.Les corps ultimobranchiaux du poulet restent actifs durant toute la vie de l'animal. L'apparition constante de formations folliculaires et kystiques, qui augmentent avec l'âge, ne traduit pas une involution globale de la glande.L'étude du développement embryonnaire permet d'expliquer certaines particularités morphologiques des corps ultimobranchiaux. Les premiers signes d'activité sécrétoires sont décelables à 11 jours d'incubation. La glande paraît très active vers la fin de la vie embryonnaire; un stockage important de matériel sécrétoire s'observe immédiatement après l'éclosion.

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Ultrastructure of the ultimobranchial body of the chickI. Normal aspect and development

Summary The ultimobranchial body of the chick consists of glandular cords made up of main secretory cells and supporting cells. According to the diameter of the secretory granules at least two main cell types can be distinguished: cells with small granules (200 m) and cells with large granules (250–300 m). This morphological difference does not necessarily implicate different hormonal secretions. The secretory granules are not preserved by simple osmium fixation; in as much as this point is concerned they behave like the granules of the parafollicular thyroid cells of mammals with which the ultimobranchial bodies are probably homologous.The ultimobranchial body of the chick remains active during the whole life of the animal. The constant appearance of follicular and cystic structure, which increase with aging, does not demonstrate an overall involution of the gland.The study of the embryonic development explains different morphological pecularities of the ultimobranchial body. The first indications of secretory activity are seen eleven days after incubation. The gland appears to be highly active towards the end of the embryonic life. An important accumulation of secretory material is observed immediately after hatching.

     

Le Macronucleus Hétéromere de Quelques Ciliés

SUMMARY. In ciliates belonging to the two gymnostome families Chlamydodontidae and Dysteriidae as well as to the order Chonotrichida the macronucleus is composed of two parts which are distinct but in very close juxtaposition. One part, here called "orthomerous," contains granules or microsomes of desoxyribonucleoprotein and several nucleoli; it thus shows the normal structure of a macronucleus of the ordinary type. The other part, "paramerous," contains desoxy-ribonucleic acid diffused, apparently, throughout a homogeneous karyolymph and possesses, in addition, several nucleoli and an endosome of desoxyribonucleoprotein.
The three groups of ciliates under discussion are closely related and constitute an assemblage of forms remarkably evolved. The "heteromerous" structure of their macronuclei must be considered as a secondary acquisition and a differentiation of the "homeomerous" type which characterizes the structure of the macronucleus in most other ciliates.     

L'appareil de Golgi des Ciliés. Ultrastructure, particulièrement chez Paramecium

Electronmicroscopic study of Coleps, Colpidium, Stylonychia, and especially of Paramecium confirmed the presence of the Golgi complex in these fresh-water ciliates. The complex consisted of numerous dictyosomes scattered throughout the cytoplasm. Each dictyosome included a few flat, partly reticulated saccules lying parallel to a cistern of rough endoplasmic reticulum which was free of ribosomes on the side exposed to the dictyosome. A unique layer of vesicles, characterized by constant size and a thick wall, separated the endoplasmic reticulum from the dictyosomes. The vesicles could be regarded as transition vesicles. Coated vesicles were seen in continuity with some of the flattened saccules. The possible role of the Golgi complex in the physiology of ciliates is discussed.     

A Propos D'observations Sur L'ultrastructure Du Cilié Cyrtolophosis Mucicola Stokes, 1885

RESUME L'étude détaillée du cortex et des organelles buccaux de Cyrtolophosis mucicola montre que ce Cilié possède une organisation structural corticale comparable à celle de Woodruffia, Platyophrya, Kuklikophrya et des Colpoda . Tout en restant conforme au plan général d'organisation de ces derniers, il a des variations spécifiques décelées au niveau des organelles buccaux qui confirment la position de C. mucicola dans la famille des Cyrtolophosididae , incluse dans le sous-ordre des PLATYOPHRYINA.