Annales des Sciences Naturelles - Zoologie et Biologie Animale最新文献

We use Gomphocerus sibiricus, a very common locust, strictly located between 2 000 and 2 800 m, in order to test its degree of susceptibility when treated with toxic agents. This species is extremely useful for histological investigations, all its organs having large cells, the fine structure of which appears quite remarkable. Our aim is to establish a practical method for evaluating industrial air poisoning, the consequences of which are soil and grass-eater poisoning.The present work is only a first step where we use two well known drugs, 6-mercaptopurine, a powerful antimetabolite, and colchicine, strongly antimitotic. We studied three mitotic rich tissues: testis, midgut epithelium and cœcal epithelium. (i) 6-MP induces chromosomal abnormalities even with a low dosage of the drug. During prophase, it appears that the colorability into each chromosome can be extremely irregular, leading to the idea of an excessive asynchronism. Breakage and loss of chromosomes have been frequently observed, inducing multinuclear and giant cell formation. All this corresponds to what can be called ‘antimetabolic syndrome’, (ii) Colchicine induces well known mitotical abnormalities depending on microtubule disturbance: at 3.6 and 1.7·10⁻⁴ M, this drug induces essentially classical ball and exploded metaphases which are considered as arrested mitosis (stathmocinesis). Moreover, we saw that a low dosage, 0.8·10⁻⁴ M, first induces a stimulation of mitosis for 4 hours, then a true antimitotic effect finally leading to synchronization (13^th hour) as a recovery. We can underline the fact that Gomphocerus clearly shows a differential cellular and mitotical sensitivity when treated with the drugs we used; consequently, this species appears very useful for experimental histo-cytological research. The complex, but clear-cut organisation of locusts is an advantage which gives us opportunities for ulterior research, histological or not, working with other drugs the effects of which could also concern other organs.

The spermatophore and spermatozoon of the calanoid copepod A. salinus, were investigated by light and electron microscopies. Mature spermatozoa were found within the spermatophore in the seminal vesicle at the end of the deferent duct. The cells measured 2–3 μm in diameter and were almost spherical; the nucleus was mixed with the cytoplasm as no envelope was present to separate them. They lack flagellum and any acrosome-like structure. The dispersed chromatin forms small granules surrounding the mitochondria, characterised by a small number of highly modified cristae. Under the plasmatic membrane, a group of electron-dense lamina enclose the whole cytoplasm. In the final phase of spermiogenesis, the dismantling of the nuclear envelope, the formation of chromatin granules and the modification of mitochondria occur. This process takes place simultaneously with the synthesis of the components of the spermatophore by the epithelial cells of the deferent duct. All these characteristics of the sperm of A. salinus identify it as being a peculiar case among copepoda.

The dermal covering of most batoid fish is constituted by dermal denticles and by different series of tubercles or thorns. The repartition and the morphological variations of these structures can provide complementary information about the taxonomy of skates and rays. The variations in these dermal structures within Pristiforms, Rajiforms and Myliobatiforms have been studied, taking into consideration the number of tubercles, their location and their arrangement in different series. Following Hubbs and Ishiyama [30], two new terms and 15 new series are indicated. The characteristics of the arrangement and of the morphology of these structures can separate the Rajiforms, having spiny tubercles or thorns, from the Myliobatiformes, bearing lanceolate or heart-shaped tubercles. The main taxinomic characters found are: guitar fish characterized by two scapular series, one well-developed rostral series and tubercles with an anterolateral ornamentation (relief). Within this group, Rhinidae and Rhynchobatidae are set apart by the morphology of their tubercles (devoid of any anterolateral ornamentation), by the absence of a middorsal caudal series and by the presence of an outer supraspiracular series. Platyrhina and Platyrhinoidis are distinguishable by the absence of anterolateral relief and by the presence of anterolateral, lateral and parallel series. Rajoids are characterized by thorns, only one scapular series and sometimes a nucho-scapular triangle, malar and alar thorns in adults, and well-developed parallel and lateral series. Myliobatiforms are devoid of rostral, orbito-spiracular, malar, alar, anterolateral, parallel and lateral series but a caudal sting is present in most species. Sawfish are almost entirely devoid of tubercules, except for rostral ‘teeth’. The morphology and arrangement of the rostral teeth can differenciate the two genera within this family.

The present experiments were carried to investigate the effects of some growth factors (FGFs, IGF-1) on the development of limb buds in the slow-worm (Anguis fragilis L.). This serpentiform reptile is devoid of legs in adulthood; but anlagen of limbs appear during embryonic life; their existence is only temporary: their growth ceases, they regress and disappear before hatching. Treatment of embryos was performed either by injection of the drugs around the limb buds or by application of small fragments of cellulosic paper soaked in the growth factors. The embryos were treated (27 by injection, 24 by application of cellulosic paper) at the stage of the allantoic bud 0.2 mm to 0.5 mm long and at an older stage (allantoic bud 1.8 mm to 4 mm long) (21 embryos treated). The administered growth factors were FGF-2, FGF-4 and IGF-1. Dosages were around 1 000 to 3 900 ng. Anterior limb buds display only very weak sensitivity to the effect of the applied growth factors: only a small proportion of the treated embryos presented a weak hypertrophy of these buds; however, after application of a fragment of cellulosic paper soaked in FGF-2, two thickening of the somatopleure in a embryo and two salient buds in another developed in the territory of the limb, propably representing anlagen of supernumerary limbs. In 25% of the embryos treated at the stage of the allantoic bud 1.8 to 4 mm long, the anlagen of the posterior limbs were greatly stimulated under the action of FGFs and IGF-1: the volume of the treated limbs was several times greater than the one of control limbs; histological study showed in the hypertrophied buds, numerous mitoses in the mesoblast and an apical ridge which did not degenerate. These results are in agreement with previous experiments and they show that it is possible to check experimentally the evolutive regression of the limbs of Anguis embryos.

The four described species of Ciliates Hysterocinetidae are commensal of the digestive tract of Alma nilotica (Oligochaete Glossoscolecidae, from Cameroons). They have in common a sucker with two posterior lips separated by a space in which anterior extremities of a few somatic kinetics enter. The sucker is devoid of cytoskeletal fibers. Three species are new, two of which belong to the new genus Amieta (A. prolifera, A. rotundus); the third belongs to the genus Thurstonia (T. almae). The species T. kaczanowskii is redescribed. The genus Amieta differs from Thurstonia in its ovoid shape, symmetrical aspect of the sucker and transversal position of the macronucleus.

Les quatre espèces de Ciliés Hysterocinetidae décrites sont commensales du tube digestif d'Aima nilotica, Oligochète Glossoscolecidae du Cameroun. Elles ont toutes une ventouse à deux lèvres postérieures non jointives entre lesquelles pénètrent, sans interruption, les extrémités antérieures de quelques cinéties somatiques. La ventouse est dépourvue de fibres cytosquelettiques. Trois espèces sont nouvelles, deux appartenant au genre nouveau Amieta (A. prolifera, A rotundus), la troisième au genre Thurstonia (T. almae). L'espèce T. kaczanowskii est redécrite. Le genre Amieta se distingue du genre Thurstonia par sa forme ovoide, l'aspect symétrique de la ventouse et la position transversale de son macronoyau.

The intestinal epithelium of Prochilodus scrofa, a freshwater teleost fish, was studied by means of light microscopic techniques. The samples were obtained from the initial, middle and terminal portions of each intestinal loop. The pyloric caeca are lined by a simple columnar epithelium with a small striated border and a very thick basal membrane. Goblet cells, lymphocytes and eosinophil granular cells (ECGs) were observed in the epithelium of all the intestinal loops. The lamina propria of the third intestinal loop is characterized by a high glandular density. At the fourth loop and up to the rectal segment, thick flaps of mucous membrane project into the lumen, resembling the valves found in mammalian veins, apparently preventing the reflux of intestinal contents. At the fourth and fifth intestinal loops an intense intraepithelial invasion of phagocytic cells occurs (macrophage, ECG and lymphocyte). Goblet cell concentration is higher at the sixth intestinal loop and rectal segment.