Pharyngeal regeneration in the land planarian Bipalium kewense

Regeneration and Asexual Reproduction

Pharyngeal regeneration in the land planarian Bipalium kewense     

Tracking and predation on earthworms by the invasive terrestrial planarian Bipalium adventitium (Tricladida, Platyhelminthes)

The potential ecological impact of exotic terrestrial planarians will be determined in part by their sensory abilities and predatory behavior. It has been suggested that these flatworms may only encounter their earthworm prey by chance, hence restricting the breadth of species they will feed upon and the number of microhabitats in which predator-prey interactions occur. We hypothesized that those flatworms that have already successfully invaded North America (genus Bipalium) actually detect and follow chemical trails of earthworms and possess the behavioral repertoire needed to feed on the prey in a range of microhabitats. We examined: (1) the tendency of Bipalium adventitium to follow chemical trails left by injured and un-injured earthworms; (2) the behavioral repertoire and predatory success of B. adventitium feeding on three earthworm species in subterranean tunnels; and (3) the response of flatworms to the reportedly defensive secretions of the earthworm Eisenia fetida in tunnels. B. adventitium detected and followed trails of earthworm mucus and secretions left by injured and un-injured earthworms. Flatworms followed trails on a range of substrates and pursued and captured three species of earthworms in subterranean tunnels, including individuals many times their mass. Although most behavior exhibited during underground attacks was similar to that reported for surface encounters, the flatworms also behaved in ways that blocked earthworm escape from tunnels. The flatworms were less successful at preying on E. fetida than on Lumbricus rubellus and Lumbricus terrestris in underground tunnels and showed some aversion to the secretions from E. fetida.     

Serotonin in the nervous system of the head region of the land planarian Bipalium kewense

The presence and distribution of serotonin (5-hydroxytryptamine, or 5-HT) in the head region of the land planarian Bipalium kewense has been investigated by an indirect immunofluorescence technique combined with confocal scanning laser microscopy (CSLM), and also by immunogold labeling at ultrastructural level. Serotonin immunoreactivity (IR) was restricted to elements of the nervous system, such as the cerebral ganglion, and the peripheral nerve net. Most of 5-HT-immunoreactive neurons are at the periphery of the brain; they were identified as unipolar, bipolar, and multipolar neurons. The ultrastructural results using immunogold labeling confirm the location of 5-HT within electron-dense vesicles (50-120 nm in diameter), clustered both in the cell bodies and in their processes. The intense 5-HT-IR herein demonstrated for B. kewense adds new data to the poorly studied nervous system of land planarians.     

A revision of the cosmopolitan land planarian Bipalium kewense Moseley, 1878 (Turbellaria: Tricladida: Terricola)

Knowledge of the cosmopolitan land planarian Bipalium kewense is briefly reviewed. A neotype and paraneotypes are designated. External morphology and internal anatomy of the species are redescribed. Karyological studies on B. kewense reveal a diploid chromosome complement of 16; one subtelocentric, three submetacentric and four metacentric chromosome pairs. Taxonomy of B. kewense is revised and full synonomy provided. New synonomies include Placocephalus isabellinus Geba and Bipalium costaricensis Hyman. Species that phenetically resemble B. kewense are divided into three groups primarily on the basis of stripe pattern and cutaneous musculature. A differential diagnosis distinguishing B. kewense from taxa in these groups is provided. Present distribution of the species is mapped. New records are reported from Barbados, Colombia, Costa-Rica, El Salvador, Indonesia, Madagascar, Malaysia, Mauritius, Mexico, Puerto Rico, Tahiti, Taiwan and Zimbabwe. Worldwide B. kewense exhibits a disjunct distribution pattern. In Australia and in the United States a similar pattern of occurrence is evident. The species appears to be dispersed with rooted plants. The natural range of B. kewense extends from Vietnam to Kampuchea, possibly extending to Malaysia. Elsewhere it has been introduced by man. The bipaliid fauna of Vietnam, to which B. kewense belongs, appears to have closer phenetic affinities with the faunas of adjacent southern rather than northern regions.     

Ultrastructural features of the epidermis of the planarian Artioposthia triangulata (Dendy)

The epidermis of the land planarian Arthioposthia triangulatawas examined by scanning and transmission electron microscopy. Thisinvestigation revealed that the flatworm was covered entirely withcilia and was especially densely populated on the ventral surface.In all regions the epidermis consisted of a one-layered columnarepithelium resting on a prominent basement membrane, but lacking aterminal web. Various secretions were found in the epidermistogether with epidermal rhabdoids. Below the basement membraneother secretory material was visible and this included thecytoplasmic lamellated granules and adenal rhabdites. The basementmembrane consisted of fibrils with a beaded appearance and thesewere arranged parallel to the epidermal layer but did not displaycross-banding. The secretory cells above and below the basementmembrane were compared and their products characterized on thebasis of shape, size and location. Their possible function isdiscussed.     

Septate junctions in the cephalic epidermis of turbellarians (Bipalium)

Summary In the epidermis of turbellarians septate junctions of the pleated sheet type have been demonstrated in conventional thin sections and freeze fractured preparations. The structure of these junctions entirely agrees with that found in molluscs and arthropods.Financially supported by DFG (Sto 75/3,4; We 380/5)     

Histochemical and ultrastructural features of the lingual epithelium of the rat snake (Elaphe climacophora)

The histological, ultrastructural and histochemical characteristics of the lingual epithelium of the rat snake (Elaphe climacophora) were investigated by light and transmission electron microscopy. The cells in the beta-layer of the epithelium of the bifurcated apex were filled with beta-keratin fibers and an amorphous matrix. Round projections covering the surface of the epithelial cells, namely, microfacets which contained pale granules, were clearly visible on the outer faces of Oberh?utchen cells on the epithelium, and they were identified as fine granules filled with lipid. These granules might play an important role as a coating on the surface of the bifurcated lingual apex. The lipid on the surface of the lingual apex might also serve to trap and retain odorant molecules. Keratohyalin-like granules were distributed within the a-layer of the epithelium of the bifurcated apex of the tongue in the resting phase and cellular interdigitation was well developed in this region. Evidence of a shedding line was apparent under the light microscope in the cleft between outer and inner epithelial generations. The epithelial surface of the body of the tongue appeared suitable for retention of odorant and other molecules.     

Histochemical aspects of the phylohistogenetic recapitulation of the epidermis

Epidermis of human embryos and fetuses obtained at abortion and at premature delivery was studied, as well as cell carcinoma of the skin in the biopsies of cheek, external ear and lip. PAS-reaction, treatment with diastase and phenyl hydrosine, staining with alcian blue at pH 1.0 and 2.7 and with basic brown at pH 1.0 were applied. Determination of the total and cationic protein with brom phenol blue (pH 2.2 and 8.2, respectively), aminoacid debris of lisine and histidine, sulfhydril groups of cysteine, disulfate groups of cysteine and others were determined. Histochemical peculiarities of the epidermal protective zone in fetuses recapitulate the epidermal properties of water vertebrates. Presence of hydrophilic groups in the cells of nonkeratinizing type of epidermoid carcinoma resembles histochemical differentiation of amphibian epidermis. In the cells of keratinizing carcinoma, keratine detected is histologically close to that in reptilian squamae.     

Structure and regeneration of the planarian basal lamina: An ultrastructural study

The structure and regeneration of the planarian subepidermal basement membrane or basal lamina have been electron microscopically examined, particularly in relation to the changes of extracellular products at the wounded area. The intact basal lamina consists of three structural elements; namely, an electron-lucent zone, a limiting layer and a microfibrillar layer. Ultrastructural changes during wound healing have suggested that the amorphous material secreted in the interspace between the epidermal cells and blastema contains precursors of the basal lamina. Within the amorphous zone two distinct phases of the basal lamina regeneration are observed: one is a reconstitution of the limiting layer and the other is a polymerization of the microfibrils. The limiting layer arises from areas subjacent to newly developed hemidesmosomes of epidermal cells. The unit microfibrils are formed from an accumulation of the precursors through transitional smaller microfibrils. At the late stage, individual mature microfibrils are regularly lined with the limiting layer and cell membranes of the newly differentiated muscle fibres. On the basis of these observations we suggest that the planarian basal lamina is regenerated by the interaction between epidermal cells and myoblasts.     

Circular form of regeneration in an unidentified species of land planarians, Bipalium sp

The communication describes an interesting and possibly novel finding regarding a species of land planarians (Bipalium sp.) from a high altitude of Himalayan range. The regeneration in Bipalium sp. is highly interesting and the process takes about a fortnight for the completion. Accumulation of numerous basophilic cells in parenchyma at the blastema region occurs within 5 days after excision and in 7 to 9 days the head and tail regions become reorganized with the formation of functional pharynx in the tail piece. The neoblast cells in the mesenchyme and the gastrodermis cells proliferate continuously replenishing the population of stem cell for growth, reproduction, and regeneration. Many undifferentiated cells are present even in completely regenerated specimens. Sometimes middle piece regenerates apparently fuse at the blastema surface forming a peculiar circular form of Bipalium sp. where both the head and tail cut ends join completely. These regenerated individuals excepting the middle piece regenerate behave in a normal fashion within 12-14 days.     

Histochemical and ultrastructural data in the spleen of the copper-intoxicated rat

By histochemical methods and electron microscopy, the spleen of copper-loaded rat was investigated. Oxidoreducing enzymes (diaphorase, succinate dehydrogenase, lactate dehydrogenase, prolineoxidase, hydroxyproline epimerase) and phosphatases (acid, ATP-ases) were tested. In general, in the intoxicated rat, the oxidases and dehydrogenases were depressed in the splenic cells, except macrophages and endothelial cells. Prolineoxidase and hydroxyproline epimerase activities increased in reticular cells and phosphatases displayed a strong activity in all the splenic structures. Ultrastructural modifications appeared in connective fibers and some connective cells.     

An electron microscope study of primary epidermis formation in freshwater planarian embryos

Early development in freshwater planarians is generally considered to be highly modified to the point of being unique. A careful examination by TEM, however, suggests that the primary epidermis (Skaer, 1965) is formed in a rather regular manner but is partially inverted with respect to the definitive body axes. After formation of the yolk cell syncytium, the blastomeres enclosed within it increase in number in the central area. Some of these blastomeres then move peripherally as a group and fuse to form another syncytium, the primordium of the primary epidermis. This primordium contacts the surface of the yolk-cell syncytium at the place where the primordium will subsequently flow out. The primordium spreads to the opposite pole through the spaces among the syncytial and non-syncytial yolk cell masses.     

Histochemical and ultrastructural identification of neurotensin cells in the dog ileum

Summary In the dog ileum, neurotensin cells stained with immunofluorescence or immunoperoxidase proved distinct from argentaffin (EC) cells, glucagon immunoreactive (GLI) cells and pancreatic peptide immunoreactive (PP) cells. Neurotensin cells showed various degrees of reactivity with Grimelius'silver. With electron microscopy, besides EC cells, large granule cells with a thin peripheral rim of Grimelius-reactivity (L cells) and large granule cells with variable Grimelius-reactivity of the core (N cells) were found. On distributive grounds, L cells were identified with GLI cells and N cells were interpreted as neurotensin cells.     

Histochemical and ultrastructural analysis of developing adipocytes in the fetal pig

Histochemical and ultrastructural aspects of adipocyte differentiation in subcutaneous tissue of fetal pigs were analyzed in a longitudinal study. A matrix of collagen fibers surrounding adipocytes developed after the establishment of a distinct and continuous PAS-positive basement membrane. The degree of plasma membrane invagination and specialization was positively correlated with the extent of basement membrane and collagen matrix formation. Close spatial relationships between narrow, smooth endoplasmic reticulum, plasma membrane invaginations, the surface of lipid droplets and mitochondria were observed in differentiating adipocytes. Histochemical and ultrastructural criteria for the identification of preadipocytes are: (1) perivascular location; (2) mitochondria localized in the Golgi zone; (3) cytosolic glycogen; (4) rough endoplasmic reticulum with cisternae uniformly and approximately 600 A wide; (5) free ribosomes and few polysomes, and (6) lipid droplets encased by microfilaments. These criteria permitted clear distinction from obvious fibroblasts and macrophages. Other stromal cells were morphologically abnormal. Occasionally, adipocytes and perivascular cells exhibited close intercellular contacts that were morphologically distinct from intercellular contacts between contiguous endothelial cells.