bluuebunny/crossref_metadata_2025 huggingface dataset:
Amputation level‐dependent patterning in urodele limb regeneration
Authors: Dinsmore Charles E. , Hanken James
Published: February 2005

Comparison of mesopodial skeletal patterns found in native and regenerated limbs of the salamander Plethodon cinereus reveals variant patterns unique to each group. Variant patterns in native limbs are based on fusions between laterally adjacent elements (i.e., in the anteroposterior axis). Variant patterns in the mesopodia of regenerated limbs usually exhibit fusions among proximodistally adjacent elements. Analysis of regenerates derived from limb amputation at different levels shows that the axis of fusion between regenerated mesopodial elements remains the same (i.e., proximodistal) independent of amputation level. However, the frequency of specific fusion combinations is unexpectedly sensitive to amputation level. Proximal (stylopodial) amputation results in mesopodial patterns with predominantly preaxial fusion combinations; distal amputation produces mesopodial patterns with predominantly postaxial fusion combinations. This finding is discussed in the context of other recent studies in which amputation level influenced limb regeneration patterning.
Neuronal typology of the thalamic area triangularis of Gallotia galloti (reptilia, sauria)
Authors: Medina Loreta M. , Trujillo Carmen Maria , Diaz Carmen , Martin Argelia , Puelles Luis
Published: February 2005

In a Golgi study of the area triangularis (AT), a rostral nucleus of the ventral thalamus of Gallotia galloti, we have identified four major neuronal types on the basis of their morphological characteristics: medium‐sized fusiforms with two processes, medium‐sized fusiforms with three or four processes, small bipolars, and small and medium‐sized multipolars. These neurons are characterized by a simple morphology and radial arrangement. Cell size varies from small to medium, and all axons project laterally. These characteristics distinguish AT neurons from those of neighboring nuclei. In addition, we found some evidence of differential topographic distribution of each neuronal type within the nucleus. Medium‐sized fusiform neurons with two processes are located in the most ventral part, where they constitute the ventral nuclear limit. Small multipolar neurons prevail in the dorsal and ventromedial parts, and in the rest of the nucleus medium‐sized neurons, including both fusiform with three or four processes and multipolar types, are normally found. Finally, we discuss a putative homology of the reptilian AT with a part of the mammalian zona incerta.
Structure and swimming behavior of the larva of Halichondria melanadocia (Porifera: Demospongiae)
Authors: Woollacott Robert M.
Published: February 2005

Larvae of the sponge Halichondria melanadocia are of the parenchymella type and, during swimming, can change shape rapidly from cigar‐like to ovoid. Larvae collected in Hawaii displayed neither qualitative nor quantitative differences in behavior or structure from those collected in Florida. Floridian larvae were examined at 2, 28, 48, and 72 hr after release to assess anatomical changes correlated with duration of the free‐swimming period. Although 2 hr larvae were significantly longer than 48 or 72 hr larvae, other differences were not observed. Positively phototactic throughout the free‐swimming period, the larvae eventually begin to swim on or near the bottom of dishes, settle temporarily, but can resume swimming before permanent settlement is achieved. The larva is extensively flagellated and a band of long flagella separates the lateral and posterior regions. The epidermis is a tall, simple columnar epithelium composed of highly polarized, monoflagellated cells. The interior contains at least two distinct amoeboid cell types that intermesh with the basal ends of epidermal cells within a loosely defined cavity. No spicules are present. Choanocyte chambers, found within 3 of the 50 larvae that were serially sectioned, varied in size and complexity, but were not associated with canals. This report is the‐first of such chambers in Halichondria larvae. Spicules and choanocyte chambers are somatic structures associated with adults, and their appearance in larvae is presumably a consequence of a heterochronic event, most likely acceleration. The evolutionary significance of the occurrence of these traits in Halichondria larvae awaits further developmental analysis and greater phylogenetic resolution.
Cell surface changes of in situ macrophages induced by superimposed antigen
Authors: Hori Isao , Ryoyama Kazuo
Published: February 2005

Mice received an injection of sheep erythrocytes (SRBC) into the footpad “prepared” or “not prepared” with a 7‐day‐prior injection of a protein‐bound polysaccharide from Coriolus versicolor (PSK; KrestinR), and the ultrastructure of in situ macrophages was studied at various intervals after the injection. A single SRBC injection into the footpad induced linear cell arrangements of several macrophages. The macrophages showed no prominent morphological alterations after SRBC digestion. When PSK‐stimulated subcutaneous macrophages were challenged by SRBC, they rapidly sent out numerous long cytoplasmic projections which radiated in all directions. Such projections of neighboring macrophages tended to contact one another. At the following stage, a pronounced sequential alteration was noted, characterized by the interlocking of elongated projections. This provided massive aggregations of “activated” macrophages. These observations suggest the possibility that intercellular communication among “activated” macrophages was elicited, particularly in the subcutaneous region, and maintained through an intensive interaction of cytoplasmic projections. Further, the present results histologically support our previous report which shows that the “PSK‐prepared” footpad site but not the “prepared” one supports development of a splenic humoral immune response following injection of superimposed SRBC.
Postnatal development of the skin of the marsupial native cat Dasyurus hallucatus
Authors: Pralomkarn T. , Nelson J. , Gemmell R. T.
Published: February 2005

Skin development of the Northern native cat was examined from birth to weaning at 150 days post partum. An outer layer of cells, termed the periderm or epitrichium, is present on the epidermis of the newborn. This layer of cells is not discernible at 7 days post partum. Skin development of the native cat differs from that of the eutherian mammal. The periderm of the eutherian is no longer discernible when the developing hairs first penetrate the epidermis. In the marsupial, this loss of the periderm occurs well before the appearance of follicles. Melanocytes and Langerhans cells are seen at day 23 post partum, follicles at day 30, sebaceous glands at day 59, and sweat glands at day 67. Thus, when the mother first leaves her young in the nest at about days 60 to 70 of lactation, the skin is at a stage of development that will assist the young with thermoregulation. The skin continues to develop throughout lactation and attains an adult appearance by day 150 post partum.
Olfactory and vomeronasal systems of caecilians (Amphibia: Gymnophiona)
Authors: Schmidt Andrea , Wake Marvalee H.
Published: February 2005

The morphology of both the main nasal cavity and the vomeronasal organ differs among species representing six families of caecilians. The main nasal cavity is either divided or undivided. The vomeronasal organ differs in position (mediolateral, lateral), size (large vomeronasal organ in the aquatic species), and shape (mediolateral extension, vomeronasal organ with a lateral rostral projection). The great amount of respiratory epithelium of the main nasal cavity, the large vomeronasal organ, and its extensive innervation in typhlonectids may reflect both phylogeny and habitat adaptation, for these taxa are secondarily aquatic or semiaquatic and have several concomitant morphological and physiological modifications. The vomeronasal organ is associated with the caecilian tentacle as the tentacular ducts open into it. This association is further evidence for the involvement of the caecilian tentacle in vomeronasal chemoperception and may represent the mechanism by which these animals smell though the main nasal cavity is closed during burrowing or swimming. Labelings of primary olfactory and vomeronasal projections by means of horseradish peroxidase reaction reveal that the pattern of vomeronasal projections is similar in Ichthyophis kohtaoensis, Dermophis mexicanus, and Typhlonectes natans, even though T. natans possess stronger vomeronasal projections relative to olfactory projections than I. kohtaoensis and D. mexicanus. However, there are differences with respect to the patterns of olfactory projections. The olfactory projection of I. kohtaoensis is characterized by many displaced glomeruli. T. natans has the smallest olfactory projection. The nervus terminalis is associated with the olfactory system as shown by selective labelings of olfactory projections.

Six characters potentially useful for phylogenetic analysis emerge from this study of comparative morphology. The characters were subjected to analysis using PAUP to see (1) if any resolution occurred and (2) if any groups were distinguished, whether they corresponded to phylogenetic arrangements based on other morphological characters. The characters are too few to produce nested dichotomous sets for all cases, but they do support the two typhlonectid genera examined and Dermophis and Gymnopis as sister taxa discrete from other groups, and they show that species within genera cluster together.
The fine structure of the encysting salt marsh heterotrich ciliate Fabrea salina
Authors: Repak Arthur J. , Anderson O. Roger
Published: February 2005

Wall and internal organelles of the encysting salt marsh heterotrich ciliate Fabrea salina were examined by bright field and Nomarski interference contrast microscopy and by transmission and scanning electron microscopy. A mucoid sheath believed to be derived from bacteria covers the ectocyst. The possible bacterial origin of this sheath has been demonstrated experimentally by its removal and reappearence after 24 hours. Control ectocyst maintained in sterile seawater did not replace the sheath. The ectocyst has a crinkled appearance. The endocyst is composed of two layers. The inner endocyst material is continuous with that of the plug located at one end of the cyst. The two membranes are separated from one another by an interwall space filled with fibrous material. The cytoplasm, covered by an outer double membrane pellicle, contains mucocysts, pigment granules, microtubules, non‐ciliated kinetosomes, Golgi complexes, ribosome‐studded endoplasmic reticulum, and mitochondria. The endoplasm contains numerous autophagosomes, mitochondria, and food reserve materials. The macronucleus is centrally located in the cytoplasm of the encysting organism.
Effects of growth on architecture and functional characteristics of adult rat gastrocnemius muscle
Authors: Heslinga J. W. , Huijing P. A.
Published: February 2005

Changes of architecture of adult rat gastrocnemius medialis muscle (GM) due to growth were studied in relation to length‐force characteristics. Myofilament lengths were unchanged, indicating constant sarcomere length‐force characteristics. Number of sarcomeres within fibers was unchanged as a consequence of growth, allowing persistence of differences between proximal and distal fibers in all age groups. Distal fiber length at muscle optimum length was shorter for the 14‐ than for the 10‐ and 16‐week age groups despite a lack of difference of number of sarcomeres. This is indicative of a shift of optimum fiber length with respect to muscle length to lengths higher than optimum length. Some evidence for the occurrence of distribution of fiber optimum lengths with respect to muscle optimum length was found in other age groups as well, albeit of a smaller magnitude. Muscle and aponeurosis length increased substantially with growth. Functional effects of increased aponeurosis lengths were increased contributions to muscle length changes by the aponeurosis, allowing smaller fiber contributions in older animals. Fiber angle increased approximately 5° with growth. Despite the differences of architecture indicated above, muscle length range between optimum length and active slack length was constant. This was probably caused by widening of this length range in the youngest age group by variations of architecture within the muscle. It is concluded that adaptation of aspects of muscle architecture is an important mechanism for adult muscle growth in rat GM. Of these aspects regulation of muscle length seems a dominant factor.
Ultrastructure of introvert and pharynx of Halicryptus spinulosus (priapulida)
Authors: Storch V. , Higgins R. P. , Rumohr H.
Published: February 2005

The introvert of Halicryptus spinulosus bears three kinds of sensilla: buccal papillae, ordinary scalids, and dentoscalids. They are all characterized by bipolar monociliary receptor cells. The former two have apical openings at which the sensory cilia are in close contact with the ambient sea water. The pharyngeal teeth are composed of slender epithelial cells the tips of which are devoid of organelles and a thick cuticle. The anatomy of the muscle arrangement of the pharynx is described. Glands occur at the junction of the pharynx and midgut.
Tunic cords, glomerulocytes, and eosinophilic bodies in a styelid ascidian, Polyandrocarpa misakiensis
Authors: Mukai Hideo , Hashimoto Koichiro , Watanabe Hiroshi
Published: February 2005

Some unusual specialized structures of the tunic and epidermis in Polyandrocarpa misakiensis were studied histologically, histochemically, and electron microscopically. The tunic is leathery, containing fibers. Dorsal epidermal cells show cytoplasmic bulges at their apical ends, suggesting formation of tunic by the epidermis. Both siphons are characterized by a well‐developed velum. In the dorsal mantle, especially around the siphons, numerous elongate cord‐like structures of the tunic (10–30 μm in diameter) extend into the hemocoel. Each tunic cord originates from the extra‐epidermal tunic, ends distally in a spade‐shaped swelling, and is covered by flattened epidermal cells. The tunic cords probably act as connectors between tunic and mantle. Glomerulocytes, a kind of blood cell, are distributed throughout the hemocoel. They are disc‐shaped (12–13 μm in diameter, 3 μm thick), and are characterized by a concentric fiber structure in the cytoplasm. The intracellular fibers are similar to the tunic fibers both morphologically and histochemically. The glomerulocytes appear to be derived from epidermal cells; their differentiation occurs in all regions of the epidermis. The function of glomerulocytes is unknown. Small club‐shaped bodies which are intensely eosinophilic are distributed here and there in the dorsal epidermis. These eosinophilic bodies are usually located individually in epidermal pockets, and are protruded into the hemocoel. The eosinophilic body is proteinaceous and PAS‐positive; it may be a secretory product of the covering epidermis. No physiological role of the eosinophilic body is yet clear. During blasto‐genesis, incipient tunic cords, glomerulocytes, and eosinophilic bodies appear almost simultaneously at a stage shortly before the opening of siphons.
Expression of the WE3 antigen in newt epithelium originating from subcutaneous grafts of skin
Authors: Tassava Roy A. , Yang Eric V.
Published: February 2005

mAb WE3 recognizes an antigen that is developmentally regulated in the wound epithelium of regenerating newt limbs. The antigen is precociously expressed when pieces of WE3‐negative wound epithelium axe grafted subcutaneously (Tassava et al.: Recent Trends in Regeneration Research. New York: Plenum Publishing Co., pp. 37–49, 1989). In the present study, we investigated whether the WE3 antigen is expressed in epidermis of subcutaneous grafts of skin. Small pieces of limb skin were grafted into small tunnels in the lower jaw, limb, and tail, oriented either the same as (epidermis facing out) or opposite to (epidermis facing in) the orientation of the host skin. In most cases, the epithelium migrated from the graft along the wounded surface of the tunnel, closed onto itself, and formed a multilayered “emigrant” epithelium. Infrequently, the migrating epithelium combined with the wound epithelium of the insertion wound. In no case did the epithelium migrate over the cut edge of the grafted dermis. Reactivity to mAb WE3 was first seen at 4 days after grafting, when the migrating epithelium had almost closed over onto itself. By 6 days and thereafter, the entire emigrant epithelium was reactive to mAb WE3. While initially restricted to the emigrant epithelium, at 10 days after grafting and thereafter, reactivity was also seen in the epidermis that remained in contact with the dermis. Expression of the WE3 antigen was not influenced by the orientation of the graft nor by the graft site. The results show that, compared to amputated limbs, the epithelium originating from these grafts precociously expresses the WE3 antigen. Also, epidermis of grafted skin is capable of expressing the WE3 antigen.
Endothelial cells of the meningeal capillaries in the rainbow trout: A freeze‐fracture study
Authors: Caruncho Hector J. , Anadón Ramón
Published: February 2005

Meningeal capillaries are unfenestrated. They are made up of endothelial cells that have a pinocytotic caveolae density of 41 ± 11/μm2 and 89 ± 21/μm2 on the abluminal and luminal sides respectively. The total density of intramembrane particles is not significantly different between the luminal and the abluminal membranes; however, the coefficients of partition are significantly different (P< 0.001). One or two strands of tight junctions occur between adjacent cells but no gap junctions nor desmosomes exist. The density of nuclear pores is less than 3.2/μm2. An abundance of intermediate filaments and free vesicles, some of which are seriated, characterize the cytoplasm. The functional significance of these findings is discussed.
Ultrastructure of pericytes in early stages of histamine‐induced inflammation
Authors: Sims David E. , Miller Frederick N. , Donald Alan , Perricone Michael A.
Published: February 2005

Physiological and ultrastructural assessment of changes in the walls of venules in the rat cremaster muscle after administration of histamine indicates that pericytes have essential roles in the normal functioning of venules during inflammation. Fluorescein‐labelled albumin was used to quantitate macromolecular leakage and to select suitable venules for ultrastructural analysis 4 and 7 minutes after addition of histamine. Pericytes were concentrated over endothelial cell junctions and gaps. At 4 minutes, when albumin leakage was becoming detectable, gaps between endothelial cells were observed in the venule wall. In 24 serially sectioned gaps, pericytes formed covers, with contact points to the endothelial cells along the sides of the gaps. At 7 minutes, when albumin leakage was maximal, gaps with pericyte covers were still evident, but more commonly observed were pericyte covers over closed endothelial cell junctions. Spaces between the innermost pericytes and endothelial cells were enlarged by an order of magnitude, from 95 nm in controls to 872 nm at 4 minutes and 958 nm at 7 minutes. Pericytes formed coverings or bridges over inclusions of extravasated cells, fluid, proteins, and the vascular label monastral blue. The data indicate that pericytes protect the endothelial lining of venules during histamine‐induced inflammation by forming a cohesive covering across gaps.
Morphological variation in adult Xylotrupes gideon australicus (Scarabaeidae, Coleoptera, Insecta)
Authors: Allsopp P. G.
Published: February 2005

Variation in horn and body size of both sexes of Xylotrupes gideon australicus is normally distributed with no evidence of dimorphism in either sex. This contrasts with that of X. gideon gideon, in which males are dimorphic for horn length, but horn size varies within morphs. Males of X. gideon australicus are generally larger than females, but the distributions of all characters, except tarsal length, overlap considerably. Males have longer legs, presumably to facilitate mating.
Venous drainage of the pelvic fins of rays (subclass elasmobranchii: Superorder Batoidea)
Authors: Alexander R. L.
Published: February 2005

A contrast radiographic study of pelvic fin drainage in rays reveals considerable differences in patterns of drainage among the species studied. The “typical” shark pattern of drainage, to the lateral abdominal vein, is also found in rays with shark‐like morphology. However, variation in the connections of pelvic fin veins to muscular and cutaneous vessels of the pectoral fin occurs in the more “derived” batoid groups, with marked differences between rays of similar external morphology and mode of locomotion. There is a positive association between the pattern of fin drainage and the number of radial cartilages in the posterior (metapterygial) lobe of the pectoral fin. Variation in shark pelvic fin drainage may also be related to differences in pectoral fin morphology.
Surface and subsurface structures of neuromasts in tadpoles of the crab‐eating frog, Rana cancrivora
Authors: Uchiyama Minoru , Iwasaki Shin‐ichi , Murakami Toshiki
Published: February 2005

Neuromast structure in Rana cancrivora larvae was observed by scanning and transmission electron microscopy. Neuromast units, each being composed of two or three neuromasts, are arranged in several well‐defined lines in the head, body, and tail regions. The structure of neuromasts in these three regions is basically identical. The neuromast is composed of sensory, sustentacular, and mantle cells. The top of each neuromast has a hillocklike appearance, and is surrounded by four to six epidermal cells with tight intercellular junctions. Long kinocilia and many stereocilia occur in the apex of the neuromasts and are surrounded by numerous microvilli. Numerous granules are present on the apical portions of the mantle and the sustentacular cells. Four or five trapeziform mantle cells are connected closely with each other to form the shell of the neuromast. Large intercellular spaces occur between the mantle cells and the cells of the inner epidermal layers, and between the cells of the inner epidermal layer. Thus, at the apical parts of the neuromast intercellular junctions are tight and the intercellular spaces are more dilated in more basal areas. Morphologically the neuromasts of R. cancrivora larvae resemble those of generalized pond anurans, based on the grouping of Lannoo (Journal of Morphology 191:115–129, 1987a), although larvae of this species inhabit brackish water.
Dynamic shape of tapered skeletal muscle fibers
Authors: Trotter J. A.
Published: February 2005

The muscle fibers of the feline biceps femoris have tapered ends, across which tension is transmitted to the endomysium. The angle of taper of 11 ends, measured on scanning electron micrographs, varied between 0.16° and 1.18°. The muscle fibers are highly variable in cross‐sectional shape. The shape of the fibers has been quantified as the ratio (form factor [FF]) of the measured perimeter to the calculated circumference of a circle having an area equal to that contained by the fiber perimeter. The FF for 173 terminal portions of fibers varied between 1.06 and 1.85 and was found to have a highly significant negative correlation with sarcomere length. The slope of the regression line suggests that the fibers maintain both volume and surface area as they change length. These studies suggest that isovolumic muscle fibers maintain a constant surface area by changing shape as they change length.
In vivo strain in cranial sutures: The zygomatic arch
Authors: Herring Susan W. , Mucci Robert J.
Published: February 2005

Although cranial sutures presumably play a role in absorbing and/or transmitting loads applied to the skull, loading patterns on facial sutures are poorly understood. The zygomatic arch provides a comparatively isolated mechanical part of the skull containing a single suture, the zygomatico‐squamosal. In pigs the zygomatico‐squamosal suture has a short vertical segment located within the postorbital process and a longer horizontal segment which extends posteriorly. In anesthetized pigs single‐element high‐elongation strain gages were bonded over both segments of the suture. Strain was recorded during stimulation of the masseter muscles and while the lightly anesthetized animals masticated food pellets. The predominant strain patterns differed in the two segments of the suture. During mastication compressive strains predominated in the vertical segment, but tensile strains predominated in the horizontal segment. The same patterns were also produced by stimulation of the ipsilateral masseter muscle. Contraction of the contralateral masseter reversed the strain pattern, but strain levels were low and during mastication such reversals occurred only transiently. The two segments of the suture have contrasting morphologies. The vertical segment has broad, interdigitating contacts with fibers arranged in a compression‐resisting orientation. The horizontal segment has a simple tongue and groove structure with fibers arranged to resist tension. Thus, the structure of the suture reflects the predominant strain pattern.
External morphology and abundance of mouthpart sensilla in Australian Gryllacrididae, Stenopelmatidae, and Tettigoniidae
Authors: Bland R. G. , Rentz D. C. F.
Published: February 2005

Sensilla diversity and abundance were extremely high on the apex of the maxillary and labial palpi of two species of Gryllacrididae. The terminal segment of the maxillary palpi of these species had 9 and 15 sensilla types, respectively, and up to 2,834 sensilla. The labial palpi had 7 and 12 types, respectively, and up to 5,195 sensilla. Several types of multiporous smooth and ridged olfactory basiconic sensilla, and coeloconic, coelosphaeric, placoid, and multipapilliform sensilla occurred, as well as many trichoid sensilla and the more typical uniporous basiconic contact receptors. Two species of the closely related Stenopelmatidae were compared to the gryllacridids and found to have similar sensillar diversity and abundance, but three species of the more distantly related Tettigoniidae had only 4 or 5 sensilla types and a total number ranging from 320 to 960 on their maxillary palpi.
Ultrastructural features and formation of the micropylar apparatus in the cherry fly Rhagoletis cerasi
Authors: Zarani Flora E. , Margaritis Lukas H.
Published: February 2005

The micropylar apparatus (MA) in Rhagoletis cerasi (Diptera, Tephritidae) is located at the anterior pole of the egg and consists of two parts: an outer chorion and an inner vitelline membrane. Sperm entry takes place through the micropylar canal, 2.0–2.5 μm in diameter, which penetrates the micropylar endochorion and terminates in the thick vitelline membrane, thus forming the “pocket.” The pore of the micropylar canal, i.e., the micropyle, is covered by the exochorionic tuft.

The formation of the MA is accomplished by 40 micropylar cells during oogenesis. These cells secrete the successive eggshell layers: the vitelline membrane, the wax layer, the innermost chorionic layer, the micropylar endochorion, and the exochorion. Two among 40 micropylar cells differentiate and form two tightly connected projections. The latter contain a bundle of parallel microtubules and participate in the formation of the micropylar canal and the pocket. At the tip of the projections there are two thin extensions full of microfilaments. In late developmental stages the two projections and the extensions degenerate and leave the canal and the pocket behind. We also discuss the structural features of the MA in relation to its physiology among Diptera.
Choanocyte‐like cells in the digestive system of the starfish Marthasterias glacialis (Echinodermata)
Authors: Martinez A. , Lopez J. , Villaro A. C. , Sesma P.
Published: February 2005

Two types of choanocyte‐like cells have been found in the digestive tract of the starfish. Type I choanocytes are in the lining epithelium of all organs of the digestive system. These are narrow, columnar cells strongly anchored basally and expanded apically into a protuberance projecting into the lumen. A prominent flagellum surrounded by microvilli projects from the center of this protuberance. Apical cytoplasm contains numerous mitochondria, secondary lysosomes, and multivesicular bodies. A distinctive characteristic of these cells is a filament bundle that traverses the length of the cell from its region of attachment on the rootlet of the flagellar basal body to its terminus on the basal plasma membrane. Between the attenuated basal ends of type I cells are the nerve fibers of an intraepithelial nerve plexus. Thickness of the plexus is correlated with the quantity of type I cells in the epithelium.

Type II choanocytes are in the cuboidal coelomic epithelium that forms the outer layer of digestive tract organs. These cells are smaller than those of type I, and they have an apical collar surmounted by a ring of 13 microvilli. Within the collar is a cup‐shaped depression with a central flagellum. Coated vesicles, secondary lysosomes, and phagocytic infoldings are observed in and near the collar cytoplasm. Filament bundles similar to those in type I choanocytes are also observed in coelomic epithelial cells that are sufficiently tall. Injection of peroxidase into the stomach and ferritin into the coelom results in phagocytic uptake of these macromolecules by type I and type II choanocytes, respectively.
Kinematics of the pharyngeal jaws during feeding in Oreochromis niloticus (Pisces, Perciformes)
Authors: Claes Geert , De Vree Frits
Published: February 2005

Cichlids possess a complex pharyngeal jaw apparatus, the osteological components of which are two upper pharyngeal jaws, articulating with the neurocranial base, and a single lower pharyngeal jaw. Quantitative cinera‐diography revealed that pharyngeal food processing in Oreochromis niloticus involves transport, mastication, and swallowing, effected by cyclical pharyngeal jaw movements. Transport and swallowing occur by simultaneous retractions of both upper pharyngeal jaws. Food reduction (mastication) is effected by lower jaw elevation (compression) and protraction (shear) during upper jaw retraction. Each movement cycle contains a transport, reduction, and swallowing component, although their relative importance may vary within a feeding sequence. The upper and lower pharyngeal jaws show opposite anteroposterior movements during most of the cycle. Variations in the amplitudes and the durations of the different movement components reflect the consistency and the size of the food.
Postnatal development of the vomeronasal epithelium in the rat: An ultrastructural study
Authors: Garrosa Manuel , Coca Santiago
Published: February 2005

Three basic types of cells are distinguished in the rat vomeronasal epithelium at birth: bipolar neurons, supporting cells, and basal cells. Neurons at this time include both immature and differentiated cells. By the end of the first postnatal week, all neurons show morphological signs of maturity in their cytoplasm, including abundant granular and smooth endoplasmic reticulum, neurotubules, dense lamellar bodies, apical centrioles, and tufts of microvilli. During the third week microvilli are more frequently encountered and appear to be longer and more branched. Supporting cells appear well‐developed by the second day after birth. During the first ten days of life, supporting cells lose their centrioles and all of the complex associated with ciliary generation in the apical zone. Basal cells appear to be more numerous in newborns than in older animals. Protrusions projecting into the lumen are frequently observed in the epithelium of newborn animals, both on the dendrites of neurons and on supporting cells. After the third week, such protrusions are only observed in the transitional zone between the sensory and the non‐sensory epithelia of the vomeronasal tubes. In this transitional zone, a fourth cell type showing apical protrusions with microvilli differentiates. Cytoplasm in this type resembles that of neighboring ciliated cells but has no cilia or centrioles. These transitional cells are considered to be cells in an intermediate state of differentiation, between that of the differentiated neurons and supporting cells of the sensory epithelium and that of the predominate ciliated cells of the non‐sensory epithelium. The results suggest that by the end of the third week the vomeronasal epithelium is morphologically mature.
Three‐dimensional reconstruction and cross‐sectional anatomy of the thigh musculature of the developing chick embryo (Gallus gallus)
Authors: Drushel Richard F. , Caplan Arnold I.
Published: February 2005

The technique of graphical reconstruction by orthogonal projection of serial sections is used to generate three‐dimensional models of embryonic chick thigh musculature at Hamburger‐Hamilton ('51) stages 36 (day 10) and 39 (day 13). Unique and conserved anatomical landmarks are described, which can be used to specify position along the proximo‐distal axis of the thigh from cross‐sectional appearance. These landmarks provide an important reference for both current and future experimentation in which a precise developmental site must be systematically and repeatedly sampled.
Light, electron microscopical, and immunocytochemical investigation of the stomach wall of the tigerfish Hydrocynus forskahlii
Authors: Coetzee Heleen L. , Nel Maria M. , Swanepoel J. H. , Van Aswegen G.
Published: February 2005

The wall of the stomach of the tigerfish is described and compared with that of other vertebrates. Light microscopic and ultrastructural characteristics of the stomach wall correspond to a large extent to those of other vertebrates, although some differences are found. The mucosa contains (1) surface epithelium characterized by narrow columnar cells with abundant mucous granules; (2) gastric glands consisting of pepsinogenic cells of variable height, containing tubulovesicles and bearing microvilli; (3) five granulated cell types located basally in the epithelium (types 1–5); and (4) lamina propria and muscularis mucosae. Connective tissue separating smooth muscle fibers of the muscularis mucosae constitutes a stratum compactum. The submucosa contains a loose connective tissue, a tunica muscularis of inner circular and outer longitudinal layers, and a serosa of mesothelium and subjacent connective tissue. Immunocytochemical tests with antisera to five polypeptides show gastrin/cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP) immunoreactivities in some cells of the gastric glands, and somatostatin in cells lying among epithelial cells lining the gastric luminal surface or gastric pits.
Unusual membranous network with spines in the uterus of Xiphinema coomansi (Nematoda: Longidoridae)
Authors: de Kruger Johan C. W. , Heyns Juan
Published: February 2005

An ultrastructural study of the uterus of Xiphinema coomansi reveal that the numerous uterine spines present in this species are not anchored to the inner wall of the tubular uterus, but are symmetrically arranged and attached in a membranous network suspended throughout the entire length of the uterus. The spines are solid, hexagonal structures enveloped and connected in tri‐radial fashion to each other, as well as to the inner uterine wall by a continuous thin undulating membrane. The network membrane thus formed encloses numerous compartments on the luminal side of the uterus, which seems to create a type of barrier between the plicated uterine wall and a rather constricted central lumen. No such membranous intrauterine network has been reported previously in the reproductive system of nematodes.
Implications of bone morphology for moa taxonomy and behavior
Authors: Kooyman Brian
Published: February 2005

The limb bone skeleton of the moa, a family of extinct ratite birds endemic to New Zealand, is described with particular reference to the anatomical and functional significance of osteological landmark form variation. The results generally support the existing classification of moa. Four genera, Megalapteryx, Anomalopteryx, Dinornis, and Pachyornis, were found to be evolved within moa, with Emeus and Euryapteryx possibly being more primitive. Megalapteryx was found to be less mobile than other moa genera. The Dinornis species were found to be more cursorial and more mobile relative to other moa. They may also have had a different center of gravity. A marked development of the lower leg in Anomalopteryx suggested a digging habit associated with food procurement.
Ultrastructure of prostomial photoreceptors in four marine polychaete species (annelida)
Authors: Rhode Birgit
Published: February 2005

The photoreceptors of four polychaete species were investigated by transmission electron microscopy: Eteone longa and Anaitides mucosa (Phyllodocidae), Scolelepis squamata (Spionidae), and Heteromastus filiformis (Capitellidae). Four different types of light‐sensitive organs could be distinguished: 1) a simple, unpigmented rhabdomeric type; 2) a simple ocellus composed of a sensory and a pigmented cell; 3) complex eyes with a lens consisting of secretory granules; 4) a simple, unpigmented type with modified cilia. In spite of its simpler organization the fourth type is listed last, because its function as a photoreceptor seems dubious.

The first type (unpigmented rhabdomeric receptor) occurs in all four species investigated. It is the only type of photoreceptor in Heteromastus. Additionally, the two phyllodocids Eteone and Anaitides possess another kind of receptor (type 4) in close proximity to the type 1 receptor. Simple ocelli (type 2) are found in Scolelepis. A pair of complex eyes (type 3) is present in both Eteone and Anaitides, but they show important differences in the two species. First, the eyes in Eteone exhibit ciliary rudiments within the sensory processes, but such rudiments are absent in the eyes of Anaitides. Secondly, the sensory cells in Anaitides possess pigment granules, whereas in Eteone they do not. Thirdly, the lens in Eteone is composed of secretion granules of equal electron density, whereas in Anaitides the lens granules show increased electron density centrally. Lens material appears to be secreted from a single corneal cell in Eteone, and from several corneal cells in Anaitides. In both species these corneal cells are located distally outside the lens.
The follicular placenta of the viviparous fish, Heterandria formosa. I. Ultrastructure and development of the embryonic absorptive surface
Authors: Grove Bryon D. , Wourms John P.
Published: February 2005

Embryos of the poeciliid Heterandria formosa develop to term in the ovarian follicle in which they establish a placental association with the follicle wall (follicular placenta) and undergo a 3,900% increase in embryonic dry weight. This study does not confirm the belief that the embryonic component of the follicular placenta is formed only by the surfaces of the pericardial and yolk sacs; early in development the entire embryonic surface functions in absorption. The pericardial sac expands to form a hood‐like structure that covers the head of the embryo and together with the yolk sac is extensively vascularized by a portal plexus derived from the vitelline circulation. The hood‐like pericardial sac is considered to be a pericardial amnion‐serosa. Scanning and transmission electron microscopy reveal that during the early and middle phases of development (Tavolga's stages 10–18 for Xiphophorus maculatus) the entire embryo is covered by a bilaminar epithelium whose apical surface is characterized by numerous, elongate microvilli and coated pits and vesicles. Electron‐lucent vesicles in the apical cytoplasm appear to be endosomes while a heterogeneous group of dense‐staining vesicles display many features characteristic of lysosomes. As in the larvae of other teleosts, cells resembling chloride cells are also present in the surface epithelium. Endothelial cells of the portal plexus lie directly beneath the surface epithelium of the pericardial and yolk sacs and possess numerous transcytotic vesicles. The microvillous surface epithelium becomes restricted to the pericardial and yolk sacs late in development when elsewhere on the embryo the non‐absorptive epidermis differentiates. We postulate that before the definitive epidermis differentiates, the entire embryonic surface constitutes the embryonic component of the follicular placenta. The absorptive surface epithelium appears to be the principle embryonic adaptation for maternal‐embryonic nutrient uptake in H. formosa, suggesting that a change in the normal differentiation of the surface epithelium was of primary importance to the acquisition of matrotrophy in this species. In other species of viviparous poeciliid fishes in which there is little or no transfer of maternal nutrients, the embryonic surface epithelium is of the non‐absorptive type.
Magnetic resonance imaging study of the structure of the yolk in the developing avian egg
Authors: Falen Steven W. , Szeverenyi Nikolaus M. , Packard David S. , Ruocco Martin J.
Published: February 2005

Magnetic resonance imaging (MRI) techniques were used to study the morphology of the latebra and concentric rings seen in the yolk of White Leghorn eggs during development of the avian embryo. Previous studies of the macroscopic structure of avian yolk have revealed the latebra, a vaseshaped structure beneath the blastoderm composed of white yolk. The bulbous portion in the center of the yolk is termed the body of the latebra. The thinner portion extending toward the blastoderm is referred to as the neck of the latebra. As the neck of the latebra approaches the blastoderm, it flares out to become the nucleus of Pander. The remainder of the yolk often features alternating concentric layers of white and yellow yolk. These layers, which appear as rings in sections, are thought to represent the daily accumulation of yolk during oogenesis. In this study eggs were imaged with a single slice spin echo sequence using MRI parameters that maximized the visualization of the latebra and concentric rings in the egg yolk. Some experiments were conducted for 2 to 3 day periods with eggs kept in the bore of the magnet using a small incubator that was constructed using a temperature‐controlled water pump. The concentric rings of the yolk and the body of the latebra flatten and become more elliptical during development. The neck of the latebra becomes shorter and disappears around the 7th day of incubation. The body of the latebra starts to become incorporated into the embryo at about the 7th day of incubation and usually disappears by the 13th day. The concentric rings are no longer visible as distinct entities at this time. Histochemical procedures carried out as a result of MRI findings indicate that the latebra is an iron‐rich structure.
An electromyographic analysis of the biting mechanism of the lemon shark, Negaprion Brevirostris: Functional and evolutionary implications
Authors: Motta Philip J. , Hueter Robert E. , Tricas Timothy C.
Published: February 2005

The kinetics of the head and function of select jaw muscles were studied during biting behavior in the lemon shark, Negaprion brevirostris. High speed cinematography and electromyography of seven cranial muscles were recorded during bites elicited by a probe to the oral cavity. In weak bites mandible depression was followed by mandible elevation and jaw closure without cranial elevation. In strong bites cranial elevation always preceded lower jaw depression, lower jaw elevation, and cranial depression. The average duration of the strong bites was rapid (176 msec), considering the size of the animal relative to other fishes. Different electromyographic patterns distinguished the two forms of bite, primarily in activity of the epaxial muscles, which effect cranial elevation. A composite reconstruction of the activity of seven cranial muscles during biting revealed that epaxial muscle activity and consequently cranial elevation preceded all other muscle activity. Mandible depression was primarily effected by contraction of the common coracoarcual and coracomandibularis, with assistance by the coracohyoideus. Simultaneous activity of the levator hyomandibulae is believed to increase the width of the orobranchial chamber. The adductor mandibulae dorsal was the primary jaw adductor assisted by the adductor mandibulae ventral. This biomechanically conservative mechanism for jaw opening in aquatic vertebrates is conserved, with the exception of the coracomandibularis, which is homologous to prehyoid muscles of salamanders.
Sperm storage and degradation in the spermathecae of the salamander Eurycea Cirrigera
Authors: Sever David M.
Published: February 2005

Spermathecae are exocrine glands in the roof of the female cloaca that store sperm. Cytological and histochemical data indicate that the one type of secretion into the lumen is a glycoprotein. After a period of stasis in the summer, production of the secretion is initiated in the fall, coincident with an increase in ovarian follicular size. By the time of maximal follicular development and most intense mating activity in March and April, the spermathecal epithelium is filled with secretory granules. The secretory material is released into the lumen, enveloping the sperm. Many sperm remain in the spermathecae after oviposition, and most of these sperm are degraded in the spermathecal epithelium or pass through interruptions in the spermathecal walls caused by desquamation. Sperm in contact with the stromal environment are phagocytized by leukocytes. Some sperm, however, may survive in the lumen until at least the following fall. These sperm retain normal cytology, but whether or not they remain fertile and intact until a subsequent ovipository cycle is unknown.
Ca++‐ and Na+, K+‐ATPase activities in the fungiform papilla of the tongue of Rana Esculenta (Anura Ranidae)
Authors: Gioglio Luciana , Rapuzzi Giovanni , Quacci Daniela
Published: February 2005

In the fungiform papilla of Rana esculenta (Anura Ranidae), the Ca++‐ATPase is mainly distributed on the basolateral membrane of the sensory area cells (i.e., neuroepithelial, supporting, and mucous cells). Apical membranes of all cells facing the surface present a slight enzymatic activity. Lateral wall cells have a strong Ca++‐ATPase activity on basolateral and apical membranes. Strong Na+, K+‐ATPase activity occurs on the apical surface of neuroepithelial cells. Ca++‐ATPase activity is absent on the surface of endothelial cells of the capillaries located under the sensory area. These observations lead us to conclude that the sensory area of fungiform papilla is the selective way for calcium influx. Furthermore the absence of ATPase activity on the surface of the endothelial cells indicates that there is no functional barrier to calcium influx into capillary, and that calcium can be removed by vessels from the sensory area.
Scanning and transmission electron microscopic observations on the larva of Halicryptus spinulosus (priapulida)
Authors: Storch V. , Higgins R. P.
Published: February 2005

The larvae of Halicryptus spinulosus bear six rings of sensory/ locomotory appendages. Twelve pedicellate flosculi, 6 dorsal and 6 ventral, are associated with the neck–lorica junction. Newly described are two rows of 4–5 flosculi present on the dorsal and ventral plates, and 2 tubuli located on each dorsolateral and ventrolateral plate near their junction with the midlateral plate. The ultrastructure of all organ systems is described. The multilayered lorica differs significantly from that of other priapulids. The anterior fourth of the lorica is not underlain by epidermal cells. At the junction of the introvert and neck are a series of adhesive tubuli that have groups of secretory cells basally. A gland is described at the junction of the fore‐ and midgut.