bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of caudal structures of a morphogenetic mutant (Da) in the teleost fish, medaka (Oryzias latipes)
Authors: Ishikawa Yuji
Published: February 2005

Development of the internal structures of the caudal region (muscles, bones, cartilages, nerves, and blood vessels) of the Da/Da mutant medaka and of wild‐type +/+ fish was compared. Muscles and nerves were immunochemically stained by using an antibody to troponin T and antibodies to neurofilament proteins, respectively. Bones and cartilages were stained with alizarin red and alcian blue. In stages 31–32 of the Da/Da embryo, the rudiments of epurals 1, 2, and 3 differentiated dorsally opposite the sites of the ventral rudiments of the parhypural, the lower hypural plate, and the upper hypural plate, respectively. In the +/+ embryo, the rudiments of epurals 1 and 2 differentiated in the later developmental stages (after stage 34), but the rudiment of epural 3 did not differentiate. In the Da/Da embryo, the deep dorsal flexor passed dorsalwards and ended at the rudiment of epural 2, whereas the muscle passed ventralwards and ended at the rudiment of the upper hypural plate in the +/+ embryo. In the Da/Da fry, the epichordal region of the caudal fin fold grew and the notochord extended straight into the tail without bending, while in the + /+ fry, the epichordal region did not grow and the notochord turned dorsalwards within the tail. In the Da/Da fry, extra skeletal rudiments and musculature differentiated in the epichordal region of the caudal fin, whereas these supernumerary structures did not develop in the +/+ fry. The pattern of the epichordal skeleton and musculature in the caudal region of the adult Da/Da fish was an almost mirror‐image duplication of the hypochordal structures. These observations suggest that the characteristic expansion of the dorsal fin and epichordal lobe in the caudal region of the adult Da/Da fish is due to a process of ventralization, whereby the dorsal skeleton, musculature, and fin fold are stimulated to differentiate in a pattern like that which is restricted to the anal fin and hypochordal lobe of the wild type.
The ultrastructure of the compound eye of Munida rugosa (Crustacea: Anomura) and pigment migration during light and dark adaptation
Authors: Gaten Edward
Published: February 2005

The galatheid squat lobster, Munida rugosa, has compound eyes of the reflecting superposition type in which a distal cone cell layer and a proximal rhabdom layer are separated by an extensive clear zone. The eye is shown to have certain unique features. In all other reflecting superposition eyes, the clear zone is traversed by crystalline tracts formed by the cone cells. In M. rugosa a thin distal rhabdom thread, formed by the eighth retinula cell, connects the cones to the proximal fusiform rhabdoms. The cytoplasm of the other retinula cells also crosses the clear zone in a complex pattern. Fully light‐adapted ommatidia are optically isolated by limited migrations of distal shielding pigments. A reflecting pigment multilayer lines each cone to facilitate the formation of a superposition image. This also shows a light‐induced change which may limit the acceptance angle of the eye during light adaptation.
Desmosome‐like junctions between sertoli‐sertoli and sertoli‐germ cells in the ovotestis of Arion hortensis (Mollusca: Pulmonata)
Authors: Hou S. T. , Maxwell W. L.
Published: February 2005

The ovotestis of Arion hortensis was investigated by electron microscopy, using serial ultrathin sections and freeze‐fracture. Desmosome‐like junctions between Sertoli‐Sertoli and Sertoli‐germ cells (spermatogonia, spermatocytes, spermatids, and spermatids just prior to spermiation) were studied. Desmosome‐like junctions were circular when viewed en face and 90‐‐180 nm in diameter. The intercellular space at the junctional site was 15–25 nm in width. An intermediate dense line was absent.

Freeze‐fracture replicas showed that these junctions formed groups, with one to ten junctions within each group. Groups of junctions were scattered over the Sertoli cell surface. The most prominent feature of this junction was an electron‐dense plaque on the cytoplasmic face of the plasmalemma. We describe variation in the development of the electron‐dense plaque on the germ cell side at different stages in the development of the germ cell. In the spermatogonium and spermatocyte stages, desmosome‐like junctions had equally developed electron‐dense plaques. The plaques are pronounced in junctions between Sertoli cells and spermatocytes/spermatids and less developed in relation to late spermatids where nuclear condensation is complete, and appear to be lost at spermiation. Finger‐like processes arise from the Sertoli cell as desmosome‐like junctions are lost at spermiation.

Hypertonic fixative solutions containing dextrose were applied to the ovotestis resulting in cell shrinkage. The intercellular space between Sertoli cells and germ cells was increased except where the desmosome‐like junctions were present. We suggest that desmosome‐like junctions provide strong adhesive sites between Sertoli and germ cells.
Morphology and morphometry of motor endings on macaque intrafusal fibers
Authors: Sahgal Vinod , Subramani Venka , Sahgal Sudarshan
Published: February 2005

The ultrastructural studies have shown three types of motor endings in the macaque intrafusal fibers: (1) unindented axon terminals with smooth or shallowly folded postsynaptic membrane; (2) indented terminals with few postsynaptic folds; and (3) indented terminals with heavily folded postsynaptic membrane. The terminals on bag 1 and chain fibers were generally more indented than those on the bag 2 fibers. Deeply indented terminals with highly folded postsynaptic membranes were noticed on the bag 1 and chain endings in spindles from lumbrical but not the biceps muscle. In the individual intrafusal fibers from the biceps and lumbrical spindles, the degree of indentation did not correlate with the extent of postsynaptic folding (P>.01). Endings on bag 1 and chain fibers in the lumbrical spindles showed a positive correlation between indentation of terminals and their distance from the primary sensory endings (P<.01), whereas the lumbrical bag 2 endings and the biceps intrafusal endings did not (P>.01). The shape of the intrafusal motor endings thus is independent of their location but dependent on the type of intrafusal fibers.
Cellular basis of an avian countercurrent multiplier system
Authors: Post Marc , Greenwald Lewis , Stetson David
Published: February 2005

A kidney from the budgerigar (budgie, parakeet; Melopsittacus undulatus) is composed of cortical reptilian‐type nephrons (without loops of Henle) and mammalian‐type nephrons (with loops) grouped together in medullary cones. The loop of the mammalian‐type nephrons has a descending segment composed of thin and highly interdigitated cells. These thin limb cells have few mitochondria (15% of cell volume), undetectable Na+, K+‐ATPase activity, and virtually no basolateral surface amplification. Prior to the hairpin turn, the descending limb thickens, but the cells continue to lack basolateral amplification. Cells just prior to and within the hairpin turn resemble cells of the entire ascending limb. These cells are thick (there is no thin ascending segment in the avian loop), with extensive infoldings of the basolateral membrane surrounding numerous mitochondria (45% of cell volume). The area of basolateral membrane is 25 times that of the apical membrane. The basolateral membrane (but not the apical membrane) is enriched in Na+, K+‐ATPase activity. The structure of the avian mammalian‐type nephron (as epitomized by the budgie nephron) and the fact that NaCl accounts for over 90% of the osmotic activity of avian urine leads to the conclusion that the countercurrent multiplier of the avian kidney functions by active NaCl transport from the entire ascending limb. No explanation is offered for the transport specializations found in the thick descending segment of the loop, just prior to the hairpin turn.
Structure of the scales of Dermophis and Microcaecilia (Amphibia: Gymnophiona), and a comparison to dermal ossifications of other vertebrates
Authors: Zylberberg Louise , Wake Marvalee H.
Published: February 2005

The structures of the dermal scales and the cells surrounding the scales in two species of gymnophione amphibians were studied using histochemistry and light, scanning and transmission electron microscopy. Scales are composed of a basal platt of several layers of unmineralized collagenous fibers topped with mineralized squamulae. Squamulae are composed of numerous mineralized globules and mineralized, thick collagen fibers. Mineralization is therefore both spheritic and inotropic. Isolated flattened cells lie on the outer surface of the squamulae and seem to be involved in mineral deposition. Cells that line the basal plate synthesize the collagenous stroma of the plate. Each scale lies in a thin connective tissue pocket, and a large connective tissue pouch includes several scales in each annulus.

The similarities of gymnophione scales to elasmoid scales of osteichthyans are largely superficial. Aspects of mineralization and of pocket development differ considerably. There are also similarities, as well as differences, in the gymnophione scales and osteoderms of amphibians and of reptiles. We consider that such dermal structures have arisen many times in diverse lineages of vertebrates, and that these are expressions of properties of dermal collagen to support mineralization by specialized dermal cells. However, we recommend that the term “dermal scale” be used for the mineralized dermal units of osteichthyans and gymnophiones, and “osteoderm” for the dermal structures of frogs and squamates, with the understanding that the terminology recognizes certain convergent attributes of shape and structure, but not of process.
Paralysis and growth of the musculoskeletal system in the embryonic chick
Authors: Hall Brian K. , Herring S. W.
Published: February 2005

Avian embryos can be completely paralyzed by injection of neuromuscular‐blocking agents. We used a single injection of decamethonium iodide to paralyze embryos at 7, 8, or 10 days of incubation and analyzed the growth of individual bones (clavicle, mandible, ulna, femur, tibia, humerus) and of individual muscles that act upon some of those bones (clavicular and sternal heads of m. pectoralis, and mm. biceps brachii, depressor mandibulae, pseudotemporalis, and adductor externus). Growth of the bones is not equally affected by paralysis. Only 27% of clavicular growth (by mass) but 77% of mandibular growth occurred in paralyzed embryos, whereas the four long bones exhibited 52–63% of their normal growth. Analysis of muscle weight, fiber length and physiological cross‐sectional area (weight/fiber length) indicate that there was greater reduction of the muscles acting on the limbs than of those acting on the mandible, i.e., diminished growth of the skeleton is correlated with reduced muscular activity. Specific retardation of clavicular growth is due to fusion of sternal rudiments and collapse of the thorax, as well as virtual absence of the musculature that normally attaches to the clavicle. We discuss these results in the light of intrinsic and extrinsic factors governing growth of tne embryonic skeleton. Paralysis reduces skeletal growth by reducing both the movements taking place in ovo, and the loads imposed on the bones by muscle contraction, changes that represent alterations in the mechanical environment of the skeleton.
Some ultrastructural observations of leydig and sertoli cells in the testis of Tilapia rendalli following induced testicular recrudescence
Authors: Van Vuren J. H. J. , Soley J. T.
Published: February 2005

Transmission electron microscopical studies performed on the testis of Tilapia rendalli confirmed the presence of Leydig and Sertoli cells. These cells displayed characteristic morphological features and were positively identified in the interstitial tissue and lobules, respectively. Based on cytoplasmic features it appeared that Leydig cells were responsible for male sex steroid synthesis. Although no clear evidence of steroidogenesis was found in the Sertoli cells, they perform a phagocytic function in the seminiferous lobules.
Scalariform junctions in the malpighian tubules of the insects Rhodnius prolixus (Hemiptera: Reduviidae) and Aedes taeniorhynchus (Diptera: Culicidae)
Authors: Bradley Timothy J.
Published: February 2005

The ultrastructure of scalariform junctions in the Malpighian tubules of the hemipteran Rhodnius prolixus and the dipteran Aedes taeniorhynchus is described. Both autocellular and intercellular scalariform junctions are illustrated. This is the first report of scalariform junctions in the Malpighian tubules of a dipteran. When combined with previous observations by other authors, the presence of scalariform junctions has now been reported in the Malpighian tubules of insects from five orders, including ametabolous, hemimetabolous, and holometabolous forms. The cell types in which scalariform junctions were found in R. prolixus and A. taeniorhynchus differ in the direction of ion and fluid transport. The cells share the capacity to transport KCl. These same cells also possess morphological features promoting close associations of mitochondria and plasma membranes in the apical region of the cell. The possible role of scalariform junctions is discussed in light of these observations.
Morphology and innervation of the buccal glands of the southern hemisphere lamprey, Geotria australis
Authors: Cook R. D. , Potter I. C. , Hilliard R. W.
Published: February 2005

The buccal glands of adults of the Southern Hemisphere lamprey Geotria australis consist of a pair of small, bean‐shaped, hollow sacs, embedded within the basilaris muscle in the region below the eyes and to either side of the piston cartilage. Each gland, which is lined by a simple columnar epithelium and surrounded by an incomplete layer of skeletal muscle, discharges its contents into the oral cavity via a long, narrow duct. In downstream migrating young adults, the epithelial cells are low columnar, intermediate in electron density, and contain dark‐staining inclusions and numerous lipid‐like droplets. After saltwater acclimation, the epithelial cells become taller and the numbers of dark‐staining inclusions increase whereas those of lipid‐like droplets decline. By the end of the marine phase, the epithelium is more folded and now also contains dark and light cells. The ultrastructure of the epithelium shows the characteristics of both apocrine and merocrine secretion. Although intra‐epithelial nerve endings were not observed, axons and occasional neurons are present in the lamina propria. Since the skeletal muscle capsule is also well innervated and contains neurons, a local feed‐back mechanism may regulate the release of buccal gland fluid by monitoring the luminal pressure. Contractions of the skeletal muscle capsule and movements of the basilaris muscle during feeding would presumably assist the movement of secretion along the duct. The secretion possesses anticoagulating and haemolytic properties.
Functional morphology of dewlap extension in the lizard Anolis equestris (Iguanidae)
Authors: Font Enrique , Rome Lawrence C.
Published: February 2005

The dewlap is an extendible flap of skin ordinarily folded under the throat. Lizards, particularly those in the genus Anolis, extend their dewlaps during interactions with conspecifics, other lizards, and potential predators. Dewlap extension is effected by movements of elements of the hyoid apparatus. This paper describes the anatomy of the hyoid and associated musculature in Anolis equestris, a large arboreal lizard with a prominent dewlap. A mechanism for dewlap extension is proposed based on results of morphological and experimental techniques.

Specializations of the hyoid skeleton for dewlap extension include elongated second ceratobranchials and highly movable joints between the ceratohyals and the hypohyals and between the first ceratobranchials and the body of the hyoid. A well developed M. ceratohyoideus extends between the ceratohyals and the first ceratobranchials of the hyoid apparatus. During dewlap extension, the hyoid apparatus acts as a first order lever. Contraction of M. ceratohyoideus pulls the ceratohyals posterorly causing the hypohyals and the body of the hyoid to rotate dorsally around the first ceratobranchial/body joints. This movement results in the second ceratobranchials swinging forward and down, unfolding the dewlap. The relative immobility of the first ceratobranchials provides stability to the hyoid apparatus during dewlap extension. A comparison is made of dewlap extension and other hyoid displays.
Structure of the spleen of the sea bass (Dicentrarchus labrax): A light and electron microscopic study
Authors: Quesada J. , Viilena M. I. , Agulleiro B.
Published: February 2005

The spleen of sea bass (Dicentrarchus labrax) is composed mainly of red pulp, whereas the white pulp is poorly developed. The red pulp consists of clear reticular cells intermingled with blood cells, sinusoids, and melanomacrophage centers (MMCs). The MMCs are enclosed by an interrupted connective tissue capsule and show some areas in continuity with the adjacent pulp. The MMCs are formed by the association of free macrophages that have phagocytosed some blood cells. Sparse white pulp is diffuse, forming a cuff around the pulp arteries and MMCs, or occurring in small groups between the splenic cords. A longitudinal artery and vein, lying side by side, extend the length of the spleen. Frequently the capillaries are surrounded by a sheath of macrophages or ellipsoids. These macrophages may contain erythrocytes in varying degrees of degradation. Lymphopoiesis and plasmapoiesis occur in the sparse lymphold areas. Abundant plasma cell groups may indicate the presence of antibody production.
Comparative ultrastructure of ant spermatozoa (formicidae: Hymenoptera)
Authors: Wheeler Diana E. , Crichton Elizabeth G. , Krutzsch Philip H.
Published: February 2005

Mature spermatozoa from spermathecae of founding queens were obtained from 5 species of ants, representing the major subfamilies Myrmicinae (Acromyrmex versicolor, Crematogaster sp.) and Dolichoderinae (Tapinoma sessile, Conomyrma insana, Conomyrma wheeleri). The ultrastructure of ant spermatozoa has many features in common with that of higher insects and is similar to that of other Hymenoptera. Structural similarities to spermatozoa of other Hymenoptera include an acrosome containing an internal rod that extends into the nucleus, two elongate mitochondrial derivatives, a centriolar adjunct, and an axonemal arrangement of 9 + 9 + 2 that includes well‐developed coarse, or accessory, tubules. Spermatozoa obtained from A. versicolor, a species that is known to store and utilize viable sperm from this supply for over 10 years, show greater development of the mitochondrial derivatives than do the other species. The most distinctive feature of ant spermatozoa in comparison to other Hymenoptera is the large size of the centriolar adjunct relative to the other organelles. The centriolar adjunct is located posterior to the nucleus, anterior to the mitochondrial derivatives, and opposite the axoneme.
Histochemistry of acetylcholine receptors and acetylcholinesterase during the formation of neuromuscular junctions in the urodele Hynobius nigrescens
Authors: Tabuchi Masahiro , Fujikura Keiko , Inoue Sakae
Published: February 2005

The development and structure of neuromuscular junctions (n‐m‐js) in stylopodia of forelimbs of larvae and adults of Hynobius nigrescens were histochemically investigated for acetylcholine receptors (AChRs) and acetylcholinesterase (AChE) activity. In larvae, the tetramethyl rhodamine‐labelled α‐bungarotoxin (TMR‐αBT) positive areas appeared either as small fluorescent spots or fluorescent plates of various sizes. The mature fluorescent plate was found to be formed by the successive addition of spots, and the plates thus established were arranged linearly parallel to the axes of muscle fibers. AChE activity occurred almost exactly at TMR‐αBT‐positive sites. In adults, plate assemblies were often seen as a single dotted line (type A form) for both AChR binding and AChE reaction, in contrast to larval n‐m‐js in which AChE activity appeared as a continuous line. By applying the TMR‐αBT method, two other forms of adult n‐m‐js were observed: type B, a long dotted line several plates wide; and type C, with a cluster of plates randomly dispersed over the whole width of the muscle fiber. It seems that protoforms of the latter two forms of n‐m‐js appear in the muscles just before and after metamorphosis.
Ultrastructure of Mehlis' gland in the lung fluke, Paragonimus ohirai (Trematoda: Troglotrematidae)
Authors: Orido Yasuhide
Published: February 2005

Mehlis' gland of a digenetic trematode, Paragonimus ohirai, is composed of two types of secretory cells, DB and CB. The less abundant type (DB) produces dense bodies, with the cytoplasm characterized by greatly distended cisternae of rough endoplasmic reticulum. The other type (CB) synthesizes clear, vesicular bodies. Its cytoplasm contains numerous mitochondria, rough endoplasmic reticulum with narrow cisternae, and abundant Golgi complexes. Processes of the two cell types converge on the ootype‐proximal uterine wall, pass through the epithelium, and finally open into the lumen. These proximal processes contain longitudinally arranged microtubules whose luminal ends are anchored to the epithelium by ring‐form septate desmosomes. According to the distribution of the two types of processes, three different zones (DB, mixed, and CB) can be recognized within the epithelia. As the CB processes enter the lumen predominantly beyond the uterine valve region, this cell may produce secretions required for egg shell maturation or hardening. The role of DB cells (which enter the lumen more commonly in the ootype near the oviduct) remains unknown.
Rickettsiae‐like structures in the larval salivary gland cells of Drosophila auraria
Authors: Thomopoulos George N. , Neophytou Elefterios P. , Limberi‐Thomopoulos Stella
Published: February 2005

Rickettsiae‐like structures were found in the salivary gland cells of Drosophila auraria during different larval and prepupal developmental stages, from the early 3rd instar up to 14 hr after spiracle inversion. These microorganisms are surrounded by a membrane, are constantly intracellular, and occur singly or in groups. Their widespread occurrence in various tissues of other Drosophila species indicates that they can be considered as symbionts, but their actual functional significance (if any) is unknown.
Composition of external setae during regeneration and transformation of the bilaterally asymmetric claws of the snapping shrimp, Alpheus heterochelis
Authors: Read A. T. , Govind C. K.
Published: February 2005

The paired thoracic chelipeds or claws of adult snapping shrimp, Alpheus heterochelis, are bilaterally asymmetric, consisting of an enlarged and elaborate, sound‐producing major (snapper) claw and a much smaller minor (pincer) claw. These paired claws vary in the composition of their external sensilla. Both possess long serrulate and simple short setae but the snapper also have plumose setae and long serrulate setae on the plunger. The pincers differ in having short serrulate setae and, in males alone, a prominent fringe of plumoserrate setae. During regeneration of each claw type, these setal structures are gradually added over three molts to reach the pristine condition. The long serrulate and simple short setae appear first, being seen in intermolt limb buds and commonly in both claws. Setae exclusive to each claw, i.e., plumoserrate and short serrulate in the pincer and plumose and long serrulate on the plunger in the snapper, appear sparsely in either the regenerated 1st or 2nd postmolt claw, they proliferate in the subsequent 2nd or 3rd postmolt claw. Transformation of the pincer claw to the snapper type begins in the 1st postmolt stage with the loss of pincer setae and addition of snapper setae and is completed by the 3rd postmolt stage. Since changes in composition of the external sensilla are restricted to postmolt stages, the underlying hypodermis is presumably being remodeled during proecdysis.
Ultrastructure of the atrioventricular valve and ventricular endo‐ and myocardium of the tigerfish, Hydrocynus forskahlii
Authors: Nel P. P. C. , Nel Maria M. , de Wit L. J. Duyvené
Published: February 2005

General ultrastructural properties of the atrioventricular valve and the endo‐ and myocardium of the tigerfish Hydrocynus forskahlii add further information to our knowledge of fish heart morphology. Small pieces of tissue from the heart of H. forskhalii were immersion‐fixed in 3% glutaraldehyde in Sörensen's phosphate buffer. Samples were postfixed in 1% osmium tetroxide and processed for transmission electron microscopy using standard techniques. The atrioventricular valve consists of dense collagen and fibroblasts lying between two layers of squamous endothelial cells. The ventricular endothelium consists of squamous cells with large nuclei protruding into the lumen of the ventricle. These cells lie on a basal lamina which overlies loose collagen in the subendothelial space. The ventricular myocardium is built up of distinctive nucleated fibres. Mitochondria, ribosomes, and glycogen are abundant in the sarcoplasm. Less conspicuous intercalated discs with no typical, steplike pattern are found between the myocardial cells. The Z lines as well as the I and A bands are clearly visible. The M lines are prominent, but the most important feature is the N line which is found on either side of the Z line in the lateral parts of the I band. The current research clearly underlines the fact that cardiac ultrastructure presents considerable diversity in different fish species.
Development of the glycogen body of the Japanese quail, Coturnix japonica: II. Observations of electron microscopy
Authors: De Gennaro Louis D. , Benzo Camillo A.
Published: February 2005

Transmission electron microscopic observations of the relationships of the cells of the glycogen body and those of nervous tissue in the lumbosacral spinal cord show that one day after hatching, glycogen cells at the lateral margins of the glycogen body lie in close association with elements of the neuropil in the adjacent spinal cord. Glycogen cells and their processes appear to extend into the neuropil, where they contact other glycogen cells, blood vessels, neurons, and neuroglia. Junctional complexes and synapses occur among glycogen cells, astrocytes, and oligodendrocytes. Other indications of specialized activities were surmised by the presence of annulate lamellae in continuity with extensive arrays of smooth endoplasmic reticulum in several glycogen cells. These observations enhance our earlier views that cells of the avian glycogen body are metabolically active in the synthesis and degradation of glycogen for neuronal support and myelination in the central nervous system.
Carbonic anhydrase activity in kidney and lower intestine of the European starling
Authors: Laverty Gary , Alberici Mary
Published: February 2005

A histochemical investigation of kidney and lower intestine of the European starling (Sturnus vulgaris) shows no carbonic anhydrase activity in proximal convoluted tubules, although activity is seen in similarly prepared sections of rat proximal tubules. Early distal tubule cells in the starling are stained throughout the cytoplasm and at the apical and highly infolded basolateral membranes. Late distal tubules lose apical activity and have reduced basolateral infolding, resulting in less intense staining. Darkly stained intercalated cells appear in the connecting tubules and cortical collecting ducts. Both of these segments also show intense basolateral staining. Medullary cones of the starling are highly organized, with central zones containing unstained thin descending limbs of loops of Henle, surrounded by both medullary collecting ducts with only scattered cells staining for enzyme, and by thick ascending limb segments. The latter contain many uniformly stained cells intermingled with occasional unstained cells. Scattered cells of the starling colonic villi demonstrate intense apical brush border membrane staining as well as cytoplasmic staining. Cells lining the cloaca stain less intensely. A biochemical assay for carbonic anhydrase was used to quantify enzyme activity in these tissues. Starling kidney contained 1.96 ± 0.33 (mean ± SEM) enzyme units/mg protein, less than half the activity seen in rat kidney. Stripped colonic epithelium contained 0.66 ± 0.15 enzyme units/mg protein. These quantitative results correlate well with the interpretations derived from the histochemical observations. The lack of proximal tubule carbonic anhydrase activity suggests that the avian kidney relies more on distal nephron segments to achieve net acidification of the urine.
Spermiogenesis in Odontophrynus cultripes (Amphibia, Anura, Leptodactylidae): Ultrastructural and cytochemical studies of proteins using E‐PTA
Authors: Báo Sônia N. , Dalton Gustavo C. , de Oliveira Sergio F.
Published: February 2005

Spermiogenesis in the South American leptodactylid frog Odontophrynus cultripes was analyzed ultrastructurally. The spermatids undergo morphological modification while still enclosed in microtubule‐rich processes of Sertoli cells. Electron‐dense plates resembling junctional structures appear in regions at which the spermatids lie in close contact with the surface of Sertoli cell processes. Spermatid differentiation can be divided into five distinct stages based mainly on chromatin condensation. In the late stages, the densely compacted chromatin loses reactivity to ethanolic phosphotungstic acid (E‐PTA). Helical arrangements of microtubules appear in the cytoplasm that surrounds the spermatid nucleus after the second stage. The acrosomal vesicle differentiates into a cone‐shaped acrosome that caps the anterior region of the nucleus. The connecting piece, located in the flagellum implantation zone, has transverse striations, and is continuous with the axial rod. The tail is formed by a 9 + 2 axoneme, an undulating membrane, and an axial rod that is rich in basic proteins as demonstrated by E‐PTA staining.
The functional anatomy of the shoulder in the European starling (Sturnus vulgaris)
Authors: Dial Kenneth P. , Goslow G. E. , Jenkins Farish A.
Published: February 2005

The excursions of wing elements and the activity of eleven shoulder muscles were studied by cineradiography and electromyography in European starlings (Sturnus vulgaris) flying in a wind tunnel at speeds of 9–20 m s−1.

At the beginning of downstroke the humerus is elevated 80–90° above horizontal, and both elbow and wrist are extended to 90° or less. During downstroke, protraction of the humerus (55°) remains constant; elbow and wrist are maximally extended (120° and 160°, respectively) as the humerus passes through a horizontal orientation. During the downstroke‐upstroke transition humeral depression ceases (at about 20° below horizontal) and the humerus begins to retract. However, depression of the distal wing continues by rotation of the humerus and adduction of the carpometacarpus. Humeral retraction (to within about 30° of the body axis) is completed early in upstroke, accompanied by flexion of the elbow and carpometacarpus. Thereafter the humerus begins to protract as elevation continues. At mid‐upstroke a rapid counterrotation of the humerus reorients the ventral surface of the wing to face laterad; extension of the elbow and carpometacarpus are initiated sequentially. The upstroke‐downstroke transition is characterized by further extension of the elbow and carpometacarpus, and the completion of humeral protraction.

Patterns of electromyographic activity primarily coincide with the transitional phases of the wingbeat cycle rather than being confined to downstroke or upstroke. Thus, the major downstroke muscles (pectoralis, coracobrachialis caudalis, sternocoracoideus, subscapularis, and humerotriceps) are activated in late upstroke to decelerate, extend, and reaccelerate the wing for the subsequent downstroke; electromyographic activity ends well before the downstroke is completed. Similarly, the upstroke muscles (supracoracoideus, deltoideus major) are activated in late downstroke to decelerate and then reaccelerate the wing into the upstroke; these muscles are deactivated by mid‐upstroke. Only two muscles (scapulohumeralis caudalis, scapulotriceps) exhibit electromyographic activity exclusively during the downstroke. Starlings exhibit a functional partitioning of the two heads of the triceps (the humerotriceps acts with the pectoralis group, and does not overlap with the scapulotriceps). The biphasic pattern of the biceps brachii appears to correspond to this partitioning.
New data on the osteology of some species of Bregmaceros (Teleostei, Gadiformes)
Authors: Świdnicki Jacek
Published: February 2005

Osteology of four extant species of Bregmacerotidae, Bregmaceros houdei, B. bathymaster, B. japonicus, and B. macclellandi, is described for the first time. The osteological analysis enables the recognition of two groups: (1) B. houdei and B. bathymaster, and (2) B. japonicus and B. macclellandi. Considerable differences in the structure of skull, and pectoral and pelvic girdles among the species indicate the existence of at least two phyletic lines within the genus. Knowledge of the skeleton may be of great importance for the taxonomy of fossil and extant species of Bregmaceros.
Structure and sympathetic innervation of the intracranial arteries in the giraffe (Giraffa camelopardalis)
Authors: Kimani James Kirumbi , Opole Isaac O. , Ogeng'O Julius A.
Published: February 2005

Fluorescence histochemistry discloses that the carotid rete mirabile in the giraffe has a poor sympathetic innervation. In contrast, the efferent artery of the rete (internal carotid artery) and the cerebral arteries show moderate sympathetic innervation. A certain degree of regional variability was noted in which the rostral arteries (anterior and middle cerebral) receive more sympathetic nerves than the caudal (posterior communicating and basilar) arteries. The sympathetic nerves on the giraffe cerebral vessels may constitute part of a host of mechanisms by which regional blood flow to the brain is regulated. Conversely, the paucity of sympathetic innervation of the carotid rete mirabile may indicate that this structure does not play an active role in vasoconstrictor responses during postural changes of the head.
Comments on the pelvic appendicular vestiges in an amphisbaenian: Blanus cinereus (Reptilia, squamata)
Authors: Renous Sabine , Gasc Jean‐Pierre , Raynaud Albert
Published: February 2005

A detailed description of muscular and skeletal features of the pelvi‐cloacal region of the amphisbaenian Blanus cinereus reveals that the species has real hind limbs articulating with a real pelvic girdle. Arguments support this homology: 1) a link with the vertebral column; 2) a movable articulation, showing all the features of a diarthrosis, between the femur and the acetabulum; 3) all the long bone characteristics for the femur which distally bears a horny element. The morphological peculiarities of the amphisbaenian pelvic girdle are generally close to those of lizards, but the pubis seems to be more reduced. For the same number of precloacal vertebrae, the amphisbaenians have more appendicular elements than lizards have, and this composition recalls that of the Leptotyphlopidae, Aniliidae, and Boidae. The account provides more information concerning the aponeuro‐tendinous system associated to the skeleton of the girdle and the hindlimb, the musculature, and the interrelations between the different structures of the pelvi‐cloacal region.
Structure and morphogenesis of the eggshell and micropylar apparatus in the olive fly, Dacus oleae (Diptera: Tephritidae)
Authors: Mouzaki Despina G. , Zarani Flora E. , Margaritis Lukas H.
Published: February 2005

The egg of the olive fly, Dacus oleae (Diptera, Tephritidae), is laid inside olives and the larva eventually destroys the fruit. The oocyte is surrounded by several distinct layers which are produced during choriogenesis. The chorion covering the main body of the egg outside of the vitelline membrane includes a “wax” layer, an innermost chorionic layer, an endochorion consisting of inner and outer layers separated by pillars and cavities similar to their counterparts in Drosophila melanogaster, as well as inner and outer exochorionic layers. The anterior pole is shaped like an inverted cup, which is chiefly hollow around its base and has very large openings communicating with the environment. Holes through the surface of the endochorion result from deposition of endochorionic substance around follicular cell microvilli. An opening at the apex of the cup provides an entrance for sperm entering the micropylar canal, which traverses the endochorion and continues into a “pocket” in a thickened vitelline protrusion. The micropylar canal is formed by deposition of endochorion and vitelline membrane around an elongated pair of follicular cell extensions. These extensions later degenerate and leave an empty canal about 5 μm in diameter and the narrower pocket about 1 μm in diameter. Respiration is thought to be facilitated by openings at the base of the anterior pole as well as by openings through the “plastron” around the main body of the shell.
Hind limb scaling in birds and other theropods: Implications for terrestrial locomotion
Authors: Gatesy Stephen M.
Published: February 2005

An analysis of hind limb skeletal elements of non‐avian theropods and ground‐dwelling birds was performed to reveal patterns of change in shape and proportion with size. When femora of equal length are compared, birds exhibit a significantly larger midshaft diameter than non‐avian theropods. As total limb length increases, avian femora become relatively shorter (negative allometry), while those of non‐avian theropods become relatively longer (positive allometry). Avian femoral/tibiotarsal ratios are all below 0.8 and decrease with limb size, whereas ratios of non‐avian theropods are well above 0.8 and tend to increase with limb size. In addition, avian femora exhibit a unique diameter/length relationship not seen in other theropod hind limb bones.

Several studies have shown that within the avian limb, the short, robust femur resists bending to a far greater degree than the relatively longer, slimmer tibiotarsus. This is to be expected, as analyses of running birds show that the femur is oriented relatively perpendicular to the ground reaction force throughout the stride, which would subject it to high bending moments. When compared to birds, non‐avian theropods have relatively long, slender femora that do not seem to be built to withstand the forces associated with such an orientation. Reconstructing all non‐avian theropods in avian‐like poses (subhorizontal femur, knee well flexed) with avian locomotor kinematics (relatively little hip extension at most speeds) ignores major differences in scaling between these groups of organisms.
Ultrastructural study of the blood cells of the beluga whale,Delphinapterus leucas
Authors: Williams Charles Rogers , Chapman George B. , Blake Andrea S.
Published: February 2005

General cytological and ultrastructural features of cells found in the peripheral blood of three captive beluga whales (Delphinapterus leucas) are described. We noted all major peripheral cell types common to the circulation of mammalian species, including polymorphonuclear neutrophils, eosinophils, basophils, lymphocytes, and monocytes, as well as myelocytes, erythroblasts, and plasma cells. Platelets and two populations (normal and hypochromic) of red blood corpuscles were observed.
Programmed cell death in the wing of Orgyia leucostigma (lepidoptera: Lymantriidae)
Authors: Nardi James B. , Godfrey George L. , Bergstrom Rebecca A.
Published: February 2005

Programmed cell death is an integral and ubiquitous phenomenon of development that is responsible for the reduction of wing size in female moths of Orgyia leucostigma (Lymantriidae). Throughout larval and pupal life, cells of the wing epithelium proliferate and interact to form normal imaginal discs and pupal wings in both sexes. But at the onset of adult development, most cells in female O. leucostigma wings degenerate over a brief, 2‐day period. Lysosomes and autophagic vacuoles appear in cells of the wing epithelium shortly after it retracts from the pupal cuticle. Hemocytes actively participate in removing the resulting cellular debris. By contrast, epithelial cells in wings of developing adult males of O. leucostigma do not undergo massive cell death. Wing epithelium of female pupae transferred to male pupal hosts behaves autonomously in this foreign environment. By pupation, cells of the female wing apparently are committed to self‐destruct even in a male pupal environment. Normal interactions among epithelial cells within the plane of a wing monolayer as well as between the upper and lower monolayers of the wing are disrupted in female O. leucostigma by massive cell degeneration. Despite this disruption, the remaining cells of the wing contribute to the formation of a diminutive, but reasonably proportioned, adult wing with scales and veins.
Structure of the respiratory islets of accessory respiratory organs and their relationship with the gills in the climbing perch, Anabas testudineus (Teleostei, Perciformes)
Authors: Munshi J. S. D. , Hughes G. M.
Published: February 2005

The epithelial and sub‐epithelial organization of the accessory respiratory organs of Anabas testudineus has been compared with that of gills by using light and transmission electron microscopy. The details of vascular supply of respiratory islets (RI) and gill filaments and the presence of venous sinusoids in the two systems suggest that the RI have been derived from gill filaments and lamellae. The biserial arrangement of transverse capillaries (TC) in the respiratory islets (RI) is evident under the scanning electron microscope and their homology with the gill filaments and their secondary lamellae has been established. The two sets of transverse capillaries of respiratory islets have been derived either from embryonic transverse or marginal channels of two sets of lamellae of a gill filament. These capillaries with their endothelial septate valves and tongue‐like processes offer resistance to blood flow.

Gill filaments have two vascular pathways, arterio‐arterial and arterio‐venous. However, the RI of accessory respiratory organs contain the arterio‐venous pathways. This arrangement as well as the septate transverse capillaries may lower the “pulmonary” blood pressure considerably.

Two types of mitochondria‐rich cells are identified: i) chloride cells with flat microvilli bearing surfaces, devoid of apical pit and (ii) an elongated cell type with sac‐like endoplasmic reticulum, with apical pit that comes into close contact with the complex matrix of macrophages, lymphocytes and other loose cells of the epithelium. These cells may be associated with detoxification of the internal media of fish inhabiting foul waters.
Ovary of the seahorse, Hippocampus erectus
Authors: Selman Kelly , Wallace Robin A. , Player Denifield
Published: February 2005

The ovary of the seahorse, Hippocampus erectus, is a cylindrical tube bounded by an outer layer consisting of a mesothelium and muscular wall and by an inner luminal epithelium, with a single row of developing follicles sandwiched between the two layers. Follicles are produced by a germinal ridge, which contains oogonia, early oocytes, and prefollicle cells, and which runs along the length of the ovary. The germinal ridge is an outpocketing of the luminal epithelium, as indicated by a continuous underlying basal lamina. Prefollicle cells invest diplotene oocytes and the complex eventually pinches off the germinal ridge as a primordial follicle surrounded by a basal lamina derived from the germinal ridge. Subsequent investment of the primordial follicle by elements of the theca complete the process of folliculogenesis. H. erectus has two ovaries and each ovary has two dorsally located germinal ridges. Thus, in each ovary the derived follicular lamina is bilaterally symmetrical: two temporally and spatially arranged sequences of developing follicles are produced, with the largest follicles found along the ventral midline of the ovary. The advantages of developmental, kinetic, and systemic analyses of these unusual ovaries are indicated.
Proximate developmental causes of limb length variation between Hyla cinerea and Hyla gratiosa (Anura: Hylidae)
Authors: Blouin Michael S.
Published: February 2005

Hyla cinerea and H. gratiosa are closely related treefrogs that differ at metamorphosis in the length of the hind limb relative to snout vent length. A developmental series of larvae of the two species raised under uniform laboratory conditions reveals that H. cinerea have proportionately longer legs at metamorphosis than H. gratiosa for the following reasons: 1) Hyla cinerea initiate limb growth at a smaller body size than H. gratiosa, 2) H. cinerea have a faster rate of limb growth, and 3) body growth rates in H. cinerea and H. gratiosa are nearly identical until just before metamorphosis.
Testis and gonopodium development in Anableps Dowi (Pisces: Anablepidae) correlated with pituitary gonadotropic zone area
Authors: Burns John R.
Published: February 2005

Testicular development in the viviparous fish, Anableps dowi, is described from embryonic stages through sexual maturation and is correlated with development of the gonadotropic zone of the pituitary. Only isolated spermatogonia or cysts of early spermatogonia are found in embryos 1.8 to 4.4 cm in length and postnatal specimens 5.4 to 8.8 cm in length. Cysts with more advanced spermatogonia are seen in specimens from 7.9 to 10.8 cm in length. Spermatogenetic meioses are first observed in a 10.2 cm male. Specimens greater than 12.0 cm have mature spermatozoa (partial spermatozeugmata) within the main testicular ducts, indicating gonadal maturation. The morphological transformation of the anal fin into the intromittent gonopodium is also described, using both whole and cleared specimens. Even in the smallest postnatal male available (5.4 cm), the anal fin can be distinguished from that of an equivalent sized female. Anal fin changes proceed until the mature gonopodium is developed, when body lengths greater than 16 cm are reached. Testicular maturation, defined as the presence of partial spermatozeugmata in the main testicular ducts, precedes the completion of gonopodial development. Measurements of ventral gonadotropic zone area in pituitary mid‐sagittal sections show a continuous increase from neonatal through sexually mature specimens. The results point to a role for testicular androgens in early testis development.