bluuebunny/crossref_metadata_2025 huggingface dataset:
Aqueous drainage paths in the equine eye: Scanning electron microscopy of corrosion cast
Authors: Smith Patricia , Samuelson Don , Brooks Dennis
Published: February 2005

The anterior vasculature of the pony eye was examined by the corrosion cast method. The anterior segment of the pony eye has a vascular pattern which is similar but distinct from that of other mammalian species. Large iridal veins collateralized directly with the anterior vortex venous system. The intrascleral plexus was present but formed a fine, radially oriented, extensive network. This contrasted to the circumferential larger‐diameter intrascleral plexus noted in dogs and the canal of Schlemm present in primates. The intrascleral plexus only drained posteriorly in the pony as compared to that in other species where anterior collateralizations have been described. The pattern of aqueous outflow was found to have relevance clinically in veterinary medicine and could provide insight into the frequent occurrence and treatment of equine recurrent uveitis as well as diseases of the posterior segment.
Occurrence of innervation in labral glands of Daphnia obtusa (crustacea, cladocera)
Authors: Zeni Cristina , Zaffagnini Fulvio
Published: February 2005

Electron microscopy discloses nerve endings in contact with gland cells situated in the labrum of Daphnia. Swellings of nerve fibers are in close contact with gland cell membranes, either on the cell surface or inserted into infoldings of plasma membrane. The axonal processes are single or double and lack glial wrappings. Inside the nerve fibers are vesicles of different sizes and electron density. These include granular vesicles, which often are dense‐cored, and also clearer vesicles.

Some presynaptic differentiations lie along the contact line of the axonal process with the gland cell membrane. The significance of the vesicles is discussed in terms of their possible content of biogenic amines, as described in other invertebrates.
Mechanics of glochidial attachment (Mollusca: Bivalvia: Unionidae)
Authors: Hoggarth Michael A. , Gaunt Abbot S.
Published: February 2005

Glochidia are third‐class levers in which the valves form the lever arms and the single adductor muscle produces the force. In this study the lengths of the lever arms and the areas of glochidial valves and adductor muscles were determined for 57 species of unionid glochidia. The position of the adductor muscle relative to the dorsal margin of the larval valve was also determined for each species. From these data and an analysis of the possible configurations of adductor muscle and valve dimensions, we determined that most of the glochidia within the Unionidae emphasize area of sweep during valve adduction. These glochidia possess long resistance arms and short force arms and generally had small‐diameter adductor muscles. Other glochidia, however, were found to possess one or all of the following: short resistance arms, long force arms, and large‐diameter adductor muscles. It is suggested that these glochidia are adapted for strength of valve adduction and that for these larvae a trade‐off exists between strength of valve adduction and acceptable valve gape. Furthermore, this study suggests that the mode of attachment employed by glochidia has played a major role in the development of these bivalve larvae and has produced convergence in valve shape and adductor muscle size.
Spermiogenesis in the red‐ear turtle (Pseudemys scripta) and the domestic fowl (Gallus domesticus): A study of cytoplasmic events including cell volume changes and cytoplasmic elimination
Authors: Sprando R. L. , Russell L. D.
Published: February 2005

Nuclear and cytoplasmic volume changes as well as the elimination of residual spermatid cytoplasm were investigated in the red‐ear turtle (Pseudemys scripta) and the rooster (Gallus domesticus). Nuclei of newly formed spermatids which were originally centrally located became eccentrically located within the cell in both species. Shortly thereafter the nuclear pole of the spermatid was found situated within deep crypts of a Sertoli cell. The cytoplasm of elongating spermatids was displaced along the nonacrosomal region of the nucleus and the proximal flagellum. In both species sheetlike Sertoli cell processes indented spermatid cytoplasm adjacent to the nucleus and appeared to segregate small packets of the cytoplasm. In the turtle, these packets of cytoplasm were separated from the spermatid. In both the turtle and rooster, a portion of the spermatid cytoplasm was displaced forward over the acrosomal region of the spermatid to resemble a hood. As spermatids were transported to the seminiferous tubular lumen, cytoplasmic lobes which projected forward of the spermatid head were formed by preferential flow of cytoplasm into one aspect of the cytoplasmic hood. In both species, at sperm release the cytoplasmic lobe was disengaged from the spermatid head to form a large residual body that was internalized and degraded within the Sertoli cell. Medium‐sized cytoplasmic lobes were pinched from the head and neck region of the turtle and rooster spermatids, respectively. In the turtle, small‐sized mitochondrial‐rich cytoplasmic fragments budded from the caudal head and midpiece of the spermatids and were phagocytosed by the Sertoli cell. Thus, cytoplasmic elimination occurred through (1) segregation of cytoplasmic packets by Sertoli penetrating processes (turtle), (2) elimination of large and medium‐sized residual bodies from the head (turtle and bird), and (3) budding of small mitochondrial‐rich cytoplasmic fragments from the region of the midpiece (turtle). In the turtle a 79% reduction in total cell volume occurred during spermiogenesis which was the result of an 84% cytoplasmic reduction and a 78% nuclear reduction. During spermiogenesis, the rooster lost 97% of its total cell volume due to a 97% cytoplasmic volume change and a 96% nuclear volume change.
On how the periosteal bone of the delphinid humerus becomes cancellous: Ontogeny of a histological specialization
Authors: De Buffrenil Vivian , Schoevaert Damien
Published: February 2005

In cetaceans, the bones of the flippers lack a free medullary cavity and have a cancellous texture, with compact cortices reduced or absent. The present work discusses the ontogenetic basis of these characters in terms of the ontogeny of the structure and textural bone compactness (TBC) of the humeral diaphysis in a growth series of common dolphins (Delphinus delphis). The texture of the primary periosteal deposits is compact; soon after their accretion, the deposits undergo an extensive erosion that turns them into a cancellous tissue. A diffuse endosteal front of resorption expands in parallel with the growth of the cortex and acts as small units scattered within the cortices. Starting soon after birth and continuing throughout the life of the animals, the compactness of the periosteal cortex decreases at both general and local levels. This trend correlates strongly with the increase in size of the diaphyseal section and reflects the fact that relatively more bone is eroded than deposited during growth in the cancellous parts of the cortex. In the broad sense, this is basically an osteoporotic process, which is not identical, however, to senile or disuse osteoporoses.
Somatic tissue–male germ cell barrier in Hydra viridis (hydrozoa, coelenterata)
Authors: O'Donovan P. , Abraham M.
Published: February 2005

In Hydra viridis, cordons of male germ cells lie in gonadal compartments, which are enlarged spaces between the elongated and “spongy” epidermal cells. The germ cells are surrounded by these cells, except for small areas where the interstitial cells and spermatogonia are in direct contact with the mesoglea. Cells from both epidermis and gastrodermis project cytoplasm into the mesoglea, where they contact each other and form trans‐mesogleal bridges. The latter exhibit gap junctions, which are particularly abundant at the spermary region. Here, the mesoglea is thinner then elsewhere in the body. Both epithelia are joined by septate junctions toward their apical ends, which are totally impermeable to horseradish peroxidase (HRP). HRP gained entry to the cells of both epithelia by pinocytosis. Incorporation into the cells was high at the basal disk, in the tentacles, and in the mesoglea in the lower part of the body stalk. The tracer was never found within the gonadal space of the testis during spermatogenesis. In mature spermaries during spermiation, tracer‐filled intracellular vacuoles fused with the gonadal spaces as the thin cytoplasmic columns of the epidermal cells ruptured; HRP thus gained access to the germ cells.

During spermatogenesis, germ cells of Hydra viridis are in a closed compartment. The barrier that controls the access of metabolites to the germ cells is formed by epidermal cells, thinned‐out mesoglea, and numerous transmesogleal interepithelial bridges. The presumed role of the barrier is the control of the environment (1) where interstitial cells are differentiating into spermatogonia and meiosis occurs and (2) in which ripe spermatozoa are kept immotile until spermiation.
Functional morphology of the glandula prostatica, ejaculatory valve, and ductus ejaculatorius of the silkworm Bombyx mori
Authors: Osanai Minoru , Kasuga Hiroko , Aigaki Toshiro
Published: February 2005

The penis of the silkmoth, Bombyx mori, consists of two parts covered with cuticle, the corpus penis and crus penis, and a third part, the radix penis, without a cuticle but surrounded by a thick sphincter. The radix penis is divisible into anterior and posterior parts. The ductus (d.) ejaculatorius passing through the penis has no secretory cells. In the anterior radix penis, the wall of the d. ejaculatorius is thin and without folds; in the posterior section, it is thick, with folds in its lumen. The glandula (g.) prostatica is divisible into anterior and posterior parts according to differences in the histological and morphological characteristics of the cells and their secretions, which contain many heterogeneous substances. In the anterior g. prostatica, secretions accumulate separately in the anterior and posterior sections before ejaculation. Unlike the posterior region, the anterior region displays a large mass(es) at the periphery of the lumen along the secretory cell layer. Judging from staining properties, the pearly body and the first layer of the spermatophore wall, which, after copulation, form in the female bursa copulatrix, seem to be derived from the secretions of the anterior and posterior regions of the g. prostatica, respectively. The secretion of the posterior g. prostatica contains initiatorin, which acts as a sperm‐activating factor in the inner and outer matrices of the spermatophore. An ejaculatory valve is found between the radix penis and the g. prostatica. The opening of this valve is regulated by the surrounding sphincter, thus impeding the back‐flow of secretions and seminal fluid in the radix penis and resulting in their transport outwards during ejaculation. The musculature of the d. ejaculatorius and the corpus penis promotes further transport of these secretions into the female bursa copulatrix.
Ultrastructure of the nephron of the one‐humped camel, Camelus dromedarius
Authors: Safer A. M. , El‐Sayed N. K. , Abo‐Salem K. , Al‐Shaer R.
Published: February 2005

The nephron of the one‐humped camel Camelus dromedarius was investigated by light and transmission electron microscopy. Besides the many features common to other mammalian kidneys, the nephron of the camel is unique in having an unusually thick basal lamina underlying the epithelial cells of the nephron, the thickest being found in part of the parietal layer of Bowman's capsule and the thin limb of the loop of Henle. In the latter, the membrane usually appears lamellated and contains numerous tiny vesicles. In other parts of the nephron, the basal lamina usually has a homogenous appearance. The possible significance of the thickening of the basal lamina is discussed in relation to the general high renal efficiency of the camel.
Ovarian structural specializations facilitate aplacental matrotrophy in Jenynsia lineata (cyprinodontiformes, osteichthyes)
Authors: Schindler Joachim F. , de Vries Uwe
Published: February 2005

Jenynsia lineata retains its embryos within the ovarian cavity for a prolonged gestation. In the absence of egg envelopes, maternal—embryonic transfer occurs through ovarian fluid across apposed epithelia, relatively lining the ovarian lumen and the surface of the embryos. There are no hypertrophied extraembryonic structures that could provide expanded exchange surfaces for the passage of nutrients beyond the 8‐mm stage, but structural specializations of the ovary then form, and these may sustain embryogenesis. Outgrowths of the inner lining of the ovary, villi ovariales, enter the pharyngeal cavity of the embryos via an opercular cleft remaining from early stages of development, after depletion of yolk reserves, until shortly before term. The ovary and its villi are lined by a monolayer of squamous cells showing evidence of vesicular transport of macromolecular substances both on the apical surface and at the basolateral pole. It serves for transcellular passage of maternally derived substances rather than as a source of secretory products. Most adjacent cells interdigitate, and the epithelium is continuous except for few gaps at the villous tips, which allow paracellular passage of particulate matter. These epithelial cells contain abundant filaments, electron‐dense granules within the cytoplasm and the nucleus, sparse elements of the rough endoplasmic reticulum, a Golgi apparatus, and different sorts of vacuoles. The capillaries in the intraovarian lining are spaced most densely at the ovarian wall, less so toward the tips of the villi. The villi ovariales contain a network of connective tissue that forms endotheliumlike septa, which divide the interior into numerous different‐sized loculi.
Interspecific, ontogenetic, and life history variation in the tooth morphology of mole salamanders (Amphibia, Urodela, and Ambystomatidae)
Authors: Beneski John T. , Larsen John H.
Published: February 2005

As revealed by scanning electron microscopy, three basic cusp shapes are found on the premaxillary teeth of mole salamanders: disc, cone, and club. In fully metamorphosed adults, tooth crowns are subdivided into labial and lingual cusps. Except for species of Linguaelapsus, the labial cusps of all adult bifid teeth are disc shaped; lingual cusp shape is more variable, but the taxonomic distribution of the various configurations is generally consistent within the subgroups Rhycosiredon, Ambystoma, and Linguaelapsus. The club shape appears to be a derived character state, but the cone and disc shapes may be either primitive or derived. Prior to the start of metamorphosis, all larvae have conical, monocuspid teeth. During metamorphosis these salamanders develop incipient bifid teeth that have the same basic adult pattern of cusp shapes but in which the cusps are smaller and more generalized. Crown morphology in paedomorphic ambystomatids is similar to that of older larvae; as such, paedomorphosis seems to interrupt and retard the ontogenetic sequence of development rather than to introduce (or reintroduce) novel morphologies into the developmental program. In larvae the crown is firmly attached to the tooth base along the putative zone of weakness, but in transformed adults the crown is separated from a pedicel by a narrow zone of fibrous connective tissue. This latter structural arrangement allows unidirectional lingual flexing of the crowns relative to the pedicel and appears to facilitate the process of tooth replacement.
Kinetics of tongue projection in Ambystoma tigrinum: Quantitative kinematics, muscle function, and evolutionary hypotheses
Authors: Reilly Stephen M. , Lauder George V.
Published: February 2005

The projectile tongue of caudate amphibians has been studied from many perspectives, yet a quantitative kinetic model of tongue function has not yet been presented for generalized (nonplethodontid) terrestrial salamanders. The purposes of this paper are to describe quantitatively the kinnematics of the feeding mechanism and to present a kinetic model for the function of the tongue in the ambystomatid salamander Ambystoma tigrinum. Six kinematic variables were quantified from high‐speed films of adult A. tigrinum feeding on land and in the water. Tongue protrusion reaches its maximum during peak gape, while peak tongue height is reached earlier, 15 ms after the mouth starts to open. Tongue kinematics change considerably during feeding in the water, and the tongue is not protruded past the plane of the gape. Electrical stimulation of the major tongue muscles showed that tongue projection in A. tigrinum is the combined result of activity in four muscles: the geniohyoideus, Subarcualis rectus 1, intermandibularis posterior, and interhyoideus. Stimulation of the Subarcualis rectus 1 alone does not cause tongue projection. The kinetic model produced from the kinematic and stimulation data involves both a dorsal vector (the resultant of the Subarcualis rectus 1, intermandibularis posterior, and interhyoideus) and a ventral vector (the geniohyoideus muscle), which sum to produce a resultant anterior vector that directs tongue motion out of the mouth and toward the prey. This model generates numerous testable predictions about tongue function and provides a mechanistic basis for the hypothesis that tongue projection in salamanders evolved from primitive intraoral manipulative action of the hyobranchial apparatus.
Ultrastructure of the basal lamina and its relationship to extracellular matrix of embryos of the starfish Pisaster ochraceus as revealed by anionic dyes
Authors: Crawford B.
Published: February 2005

The ultrastructure of the 51/2–6‐day‐old embryonic asteroid basal lamina (BL) was studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and after treatment with anionic dyes. Conventional fixation in glutaraldehyde and osmium reveals a BL consisting of a lamina densa separated from the basal cell surface by a lamina lucida. Little or no reticular lamina is present. Material similar in appearance to the basal lamina extends into the blastocoel, forming an extracellular matrix (ECM). Following fixation in the presence of the dye ruthenium red, proteoglycan (PG) granules are visible in the lamina lucida and immediately beneath the lamina densa. The ECM consists of granules of a similar appearance, which are associated with fibers of an intermediate electron density resembling invertebrate collagen. After fixation in the presence of alcian blue under polyanionic conditions, all aspects of the basal lamina and the ECM stain very densely. The use of alcian blue in 0.3 M MgCl2 (monoanionic condition) or in low concentrations reveals a lamina densa consisting of a fine feltwork and tubule‐like structures. A meshwork composed of thick, densely stained and thinner, intermediately stained strands is embedded in the inner aspect (that adjacent to the blastocoel) of the ectodermal lamina densa. Similar elements are present in the endodermal BL, but the dense material is represented by short regions that do not form a meshwork. The dense and intermediate strands of both basal laminae also extend into the blastocoel as ECM. The tubule‐like structures extend from the dense material of the inner meshwork into the lamina densa. They also cross both the lamina densa and lucida to associatee with the basal cell membranes. The fact that the basal cell surfaces are often puckered outward at the points of contact suggests that this configuration might be providing a means whereby forces can be transferred from the ECM through the basal lamina to the cells.
Ultrastructure of the crayfish antennal gland revealed by scanning and transmission electron microscopy combined with ultrasonic microdissection
Authors: Fuller E. G. , Highison G. J. , Brown F. , Bayer C.
Published: February 2005

The antennal gland of the crayfish Pacifasticus leniusculus was studied using standard techniques for scanning electron microscopy as well as newer procedures for ultrasonic microdissection. To clarify relationships in the nephron tubule, transmission electron microscopy was employed.

The coelomosac contains elongated cells (podocytes) displaying microvilli and extensive apical blebbing. A smooth basal lamina lines the blood space that furnishes hemolymph to the coelomosac. The labyrinth consists of tall columnar cells displaying apical microvilli, numerous blebs that seem to represent an expansion of apical plasma membrane, and lateral interdigitations. The nephron tubule consists of two distinctly different areas: a proximal region of flattened cells with extensive intercellular fusions, and a distal segment of separate, dome‐shaped cells.

Despite many similarities between the crayfish kidney and the vertebrate nephron, there are striking differences. The amount of surface blebbing that occurs in the coelomosac and labyrinth far exceeds that of the vertebrate nephron and may reflect its importance in the function of the crayfish kidney. The cells of the coelomosac are taller than are the vertebrate podocytes and possess less obvious arms and pedicels. In addition, the proximal segment of the nephron tubule is notable for its intercellular fusions, which are not present in the vertebrate nephron. Although the function of the intercellular fusions is unknown, they may play a role in cellular communication or the redistribution of fluids or electrolytes between cells.
Ultrastructure of the spermatozoon of Megaselia scalaris Loew (Diptera:Brachycera:Cyclorrhapha:Phoridea:Phoridae)
Authors: Curtis Sherill K. , Benner David B. , Musil George
Published: February 2005

When viewed by scanning electron microscopy (SEM), the spermatozoon of the phorid dipteran Megaselia scalaris appears threadlike, lacking distinct head and tail areas. These areas can be observed, however, in appropriately stained material. Measurements of Feulgen‐stained material reveal average lengths of the head, tail, and total cell of 18.7, 128.7, and 147.4 μm, respectively. When tested for sulfhydryl and disulfide groups, the head displays only disulfide groups. Transmission electron microscopy (TEM) reveals 12 different regions: three (1–3) in the head, four (9–12) in the tail, and five (4–8) in a short zone of overlap between the head and tail. Most of the cell lies in regions 9 and 11 of the tail and 3 of the head, accounting for, respectively, 37.3%, 45.7%, and 11.2% of the total length. A tubelike acrosome indents the anterior end of the nucleus. The tail originates asymmetrically in relation to the long axis of the cell as a peglike structure associated with the dorsolateral region of the nucleus. No centriole is visible, and the nucleus has a notched appearance in longitudinal sections. Two mitochondrial derivatives and an axoneme displaying a 9+9+2 microtubule configuration and ATPase activity extend throughout most of the tail. In regions 9 and 10, an asymmetrically arranged accessory body is also present. Features having possible taxonomic utility include the asymmetrically arranged accessory body, the size and shape of the acrosome, and the notched appearance of the nucleus. The present report is apparently the first to describe the spermatozoon of a cyclorrhaphous dipteran which is not a member of the Schizophora.
Coarctation of the stapedial artery: An unusual adaptive response to competing functional demands in the middle ear of some eutherians
Authors: Diamond Michael K.
Published: February 2005

In primitive eutherians, the stapedial artery is the primary supplier of blood to the nonneural tissues of the head. Beyond a certain body size, the stapedial artery can no longer function as the sole supplier to its original territory because the diameter of its stem is limited by the size of the intercrural foramen of the stapes, which exhibits strong negative allometry. Some eutherians have extended the upper limit that the diameter of the stapedial stem can attain by developing a coarctation (narrowing) at the transcrural portion of the vessel. In the Norway rat (Rattus norvegicus) and the golden hamster (Mesocricetus auratus) the coarctation develops in postnatal life and is evidently caused by a retardation in growth that keeps the diameter of the vessel at infantile dimensions. In the rat, additional reduction in the external diameter is produced by a thinning of the tunica media of the arterial wall. A comfortable gap between the wall of the artery and the sides of the intercrural foramen is maintained that most likely facilitates the attenuation of potentially disruptive low‐frequency vibrations produced by the arterial pressure pulse. The only negative side effect of a coarctation in rat‐sized animals is that resistance to flow is increased and volume flow rate is concomitantly diminished. The coarctation does not create flow disturbances downstream of the constriction. One possible additional benefit of the coarctation is a flattening out of the arterial pressure pulse. It is speculated that the capacity to develop a coarctation once a certain body size is reached is an ancient trait that dates at least as far back as the Early Cretaceous.
Ultrastructure of the attachment cells of the organ of Bellonci in Gammarus setosus (Crustacea, Amphipoda)
Authors: Steele V. J. , Oshel P. E.
Published: February 2005

The structure of the organ of Bellonci indicates that it is a sensory organ able to receive a variety of external stimuli. The suspension of the organ was investigated in the marine amphipod Gammarus setosus by light, scanning, and transmission electron microscopy. The organ is suspended ventrally by a cord whose specialized cuticular attachment is in the roof of a canal under the interantennal angle of the head. The conical end of the cord consists of five epithelial attachment cells sheathed by processes of 21 cells arranged in five tiers inside a basal lamina. The attachment cells end within a knob in the centre of a diaphragm. The cuticular attachment is confined to the knob and consists of endocuticular rods within pits on the surfaces of the attachment cells. Dorsally, the long processes of the attachment cells form a net over the surface of the organ and reunite in the dorsal suspensor, which anchors the organ in the epidermis at the crown of the head. The attachment cells are characterized by extensive hemidesmosomes and dense core granules at both attachment sites and by microtubules that extend through their entire length of up to 1 mm in the adult. The large size, cephalic position, elaborate structure, and suspension of the organ suggest that it is of considerable importance in the sensory capability of aquatic Malacostraca.
Chemical access to the vomeronasal organs of a plethodontid salamander
Authors: Dawley Ellen M. , Bass Andrew H.
Published: February 2005

Plethodontid salamanders have unique nasolabial grooves that may function as “capillary tubes” to convey chemicals to the vomeronasal organ when these animals nose‐tap. 3H‐proline was placed at the base of these grooves in Plethodon cinereus, and autoradiography revealed large concentrations of radioactive material in the vomeronasal organs. There was no significant accumulation of radioactive material in the main olfactory epithelium. Salamanders with blocked nasolabial grooves lacked significant accumulation of material in their nasolabial grooves or vomeronasal epithelia, although some salamanders had radioactive material in the posterior portion of their vomeronasal organ that had entered through the internal nares. Anteriorly placed vomeronasal organs situated adjacent to the posterior limits of the nasolabial grooves may insure that nose‐tapping primarily stimulates the vomeronasal sensory epithelium.
Ovarian follicle development during vitellogenesis in the house cricket Acheta domesticus
Authors: Dennis John C. , Bradley James T.
Published: February 2005

To determine the morphological correlates of vitellogenin uptake and distribution, vitellogenic ovarian follicles of Acheta domesticus were examined by light and transmission electron microscopy. Yolk deposition was usually restricted to the terminal follicle of each panoistic ovariole, but if the terminal follicle had completed vitellogenesis and had not yet been ovulated, the penultimate follicle was often vitellogenic. Vitellogenesis occurred only in the ovaries of adults, with follicles representing all stages of vitellogenic development occurring simultaneously within a single ovary. Vitellogenic follicles were 0.75 to >2.0 mm long. The single irregularly shaped nucleus of each follicle cell contained two to three nucleoli. During vitellogenesis the epithelium of individual follicles progressed from columnar to cuboidal to squamous. The distribution of cytoplasmic organelles within individual follicle cells was polarized during early and middle stages of vitellogenesis. Near the end of vitellogenesis, polarity disappeared, the follicular epithelium became squamous, and the frequency of vesicular and multivesicular bodies in the follicle cell cytoplasm increased. A well‐developed capability for follicle cell protein synthesis and secretion throughout vitellogenesis was indicated by abundant rough endoplasmic reticulum and Golgi bodies. Receptor‐mediated endocytotic activity by the follicle cells during all stages of vitellogenesis was suggested by omnipresent coated pits on all surfaces. Septate junctions, gap‐like junctions, and desmosomes all occurred in the lateral membranes, while gap‐like junctions predominated at the oocyte–follicle cell interface. In follicles longer than 1 mm, adjacent follicle cells were separated by intercellular channels that widened to as much as 10 m̈m by the completion of vitellogenesis. The channels contained a flocculent material, and a similar‐appearing material filled the space between the oolemma and follicle cell apical membranes. The oolemma contained a profusion of coated pits throughout vitellogenesis.
Organization of giant interneuron projections in thoracic ganglia of the cockroach Periplaneta americana
Authors: Stubblefield G. Thomas , Comer Christopher M.
Published: February 2005

We have investigated the structural organization of the wind‐sensitive giant interneurons in the thoracic ganglia of adult American cockroaches. These seven bilaterally paired interneurons have long been thought to play a role in directing the wind‐elicited escape response of the animal. Each of the giant interneurons was labeled individually by intracellular injection of cobaltic hexamine chloride. An individual giant interneuron could be reliably identified from animal to animal based on its branching pattern in thoracic ganglia. The axons of the giant interneurons are situated on each side of the nerve cord in two recognizable subgroups. Comparisons of the axonal arbors of the dorsal and ventral subgroups showed that they project into distinct but partly overlapping regions of thoracic ganglia. Three of the giant interneurons were found to have axonal arbors that cross the longitudinal midline of thoracic and abdominal ganglia. Bilateral pairs of these giant interneurons were labeled concomitantly, and many of the individual neurites from these cells appeared to be closely apposed. All these morphological characteristics are discussed in relation to the connectivity and functional significance of the giant interneurons.
Internal anatomy ofHypochthonius rufulus(acari: Oribatida)
Authors: Smrž Jaroslav
Published: February 2005

The internal anatomy of juveniles and adults ofHypochthonius rufulusselected as a model species representing the lower Oribatida was investigated histologically and compared with the published characteristics of higher oribatid internal anatomy. In this species, the cuticle is weak and flexible, consisting of epicuticle and endocuticle on the body, but including an exocuticle between the epicuticle and endocuticle of the legs. Walls of the mesenteron in the digestive tract are of uniform thickness and structure without any regional thickening, and there are no proventricular glands. The hindgut is apparently divided into five parts: colon 1 and 2, rectum 1 and 2, and anal atrium; food bolus exhibits a multilamellar structure in this section. The glandular system is less diversified than in some other oribatids. Tracheae are apparently lacking. Females possess only two relatively large eggs, filling one‐half of opistosoma, and they lack ovipositors. Eggs are present in females during the whole year. Gonad buds appear first in the protonymph stage. Only one male was found among 146 adults studied. No male external organ (aedeagus or penis) is present.
Development of the ethmoidal structures of the endocranium in the anuran Pipa pipa
Authors: Roček Zbyněk , Veselý Milan
Published: February 2005

Investigation of eight developmental stages by means of serial sections and subsequent graphic or wax model reconstructions, as well as by means of cleared‐and‐stained and dissected material, revealed that the ethmoidal endocranium in Pipa pipa consists in early states of a single horizontal ethmoid plate lacking labial cartilages. Later in the course of development, structures comparable with those in other anurans appear, though modified and of reduced size. These adult structures arise from the new cartilaginous tissue located above the former larval ethmoid plate, whereas the latter entirely disappear. This phenomenon can be observed also in P. carvalhoi and in Xenopus laevis; hence, it supposedly occurs in all pipids. On the other hand, in anuran larvae, which develop cornua trabecularum in the ethmoidal region, these persist in adults as part of the nasal septum. Positional and developmental differences suggest that, although the ethmoid plate and the cornua trabecularum arise from the same region of the cranial neural crest, they are not fully corresponding structures. Comparison with adults of other pipid genera confirmed the conclusion of some earlier investigators that P. pipa is the most specialized among pipids.
Morphological differentiation of the müller cell: Golgi and electron microscopy study in the chick retina
Authors: Prada F. A. , Magalhaes M. M. , Coimbra A. , Genis‐Galvez J. M.
Published: February 2005

The sequence of morphological differentiation of Müller cells in the chick retina was investigated in relation to the differentiation of the retinal neurons using the Golgi method. From the beginning of differentiation, the Müller cell develops spurs and lateral processes. Some of these glial processes become transformed into accessory prolongations of the Müller cell. From the 17th or 18th day of incubation, the morphology of the Müller cells is similar to that of the adult retina. On the basis of their inner prolongation, two types of Müller cells were identified. The first type, with diffuse and abundant descending processes, is identical to that described classically. The second type is a cell characterized by sparse and scanty inner ramifications.

This report also describes electron microscopic observations of Müller cells and their enwrapping relationship with the axons of the optic nerve fiber layer.
Tectorial structures on the inner ear sensory epithelia of Proteus anguinus (Amphibia, caudata)
Authors: Bulog Boris
Published: February 2005

The tectorial structures of the inner ear of the proteid salamander Proteus anguinus were studied with transmission and scanning electron microscopy in order to analyze the ultrastructure of the otoconial membranes and otoconial masses of the maculae and the tectorial membrane of the papilla amphibiorum. Both otoconial and tectorial membranes consist of two parts: (1) a compact part and (2) a fibrillar part that joins the membrane with the sensory epithelium. Masses of otoconia occupy the lumina above these membranes.

There are two types of calcium carbonate crystals in the otoconial masses within the inner ear of Proteus anguinus. The relatively small otoconial mass of the utricular macula occupies an area no greater than the diameter of the sensory epithelium, and it is composed of calcite crystals. On the other hand, the enormous otoconial masses of the saccular macula and the lagenar macula are composed of aragonite crystals. In the sacculus and lagena, globular structures 2–9 m̈m in diameter were discovered on the lower surfaces of the otoconial masses above the sensory epithelia. These globules show a progression from smooth‐surfaced, small globules to large globules with spongelike, rough surfaces. It is hypothesized that these globules are precursors of the aragonite crystals and that calcite crystals develop similarly in the utriculus. The presence of globular precursors in adult animals suggests that the formation of new crystals in the otoconial membranes of the sacculus and lagena of Proteus is a continuous, ongoing process.
Histochemical analysis of newly synthesized and accumulated sulfated glycosaminoglycans during musculogenesis in the embryonic chick leg
Authors: Young Henry E. , Carrino David A. , Caplan Arnold I.
Published: February 2005

The leg musculature from 11, 14, and 17 day chick embryos was analyzed histochemically to investigate the temporal and spatial distribution of various types of sulfated glycosaminoglycans present during skeletal muscle development. Types of glycans were identified by selective degradation with specific glycosidases and nitrous acid coupled with Alcian blue staining procedures for sulfated polyanions and with [35S]sulfate autoradiography. On day 11, radiolabeled chondroitin sulfate glycosaminoglycans are localized extracellularly in both the myogenic and connective tissue cell populations. By day 17, incorporation of [35S]sulfate into chondroitin sulfate is substantially reduced, although Alcian blue‐stained chondroitin sulfate molecules are still detectable. With increasing age and developmental state of the tissues, radiolabeled and stained dermatan sulfate and heparan sulfate progressively increase in relative quantity compared to chondroitin sulfate both in muscle and in associated connective tissue elements. These changes in glycosaminoglycans correlate well with similar changes previously determined biochemically and further document the alterations in extracellular matrix components during embryonic skeletal myogenesis.
Number and distribution of hair cells in the utricular macula of some avian species
Authors: Jørgensen J. Mørup
Published: February 2005

The utricular macula was examined in 20 bird species belonging to 13 families. Two types of hair cells, a bouton‐innervated and a calyceal hair cell, were found. The calyceal hair cells are found situated in two zones that follow the anterior and lateral borders of the utricular macula in all except two species. In the rhea and mute swan, only one zone was found, corresponding to the inner zone of the other species. The majority of calyceal hair cells are present in the anterior and lateroposterior part of the inner zone. They are often gathered in a common calyx. More hair cells are found within the same calyx in birds than described in previously examined reptile and mammalian species. In nine specimens of four species belonging to four different families, the calyceal hair cells constitute between 7 and 12% of the total number of hair cells, which varies from about 20,000 to 40,000.
Parthenogenetic reproduction in the neotropical unisexual lizard,Gymnophthalmus underwoodi(Reptilia: Teiidae)
Authors: Hardy Laurence M. , Cole Charles J. , Townsend Carol R.
Published: February 2005

All adult specimens known forGymnophthalmus underwoodiare females, and their mode of reproduction has been a mystery. In order to rule out the possibility of a bisexual mode of reproduction by means of mating with undiscovered males, hermaphroditism, or sex reversal during ontogeny, we examined hundreds of serial histological sections of complete reproductive tracts from juveniles and adults representing two generations of a lineage raised in captivity. In addition, comparative dissections were performed on other individuals and other species, and reproduction to the F5generation was documented in laboratory colonies ofG. underwoodiestablished from Trinidad and Surinam stocks. A lineage of three successive generations was produced entirely by individuals that were maintained in isolation from the moment of hatching.

All specimens ofG. underwoodiproved to be female, with reproductive anatomy identical to that of females of closely related, bisexual species ofGymnophthalmus: G. pleeiandG. speciosus. Thus,G. underwoodiis an all‐female species that reproduces by means of strict parthenogenesis, in the absence of sperm.

As in the macroteiids of the genusCnemidophorusstudied previously,Gymnophthalmushas functional mesonephric kidneys throughout life.

G. underwoodiranks among the smallest amniotes, adults weighing about 1.2 gm and having a body length of 36–43 mm. Data from the laboratory colonies indicate the following: clutch size, 1–4 (X= 2); mean egg size about 9.4 × 6.5 mm (weight, 0.23 gm); development time, up to 61 days or more; hatchling body length, 16–19 mm (X= 18); hatchling tail length, 18–25 mm (X= 22); hatchling weight, 0.09–0.14 gm (X= 0.115); reproduction continuous year round with individuals able to produce successive clutches in less than a month but quiescent periods following reproductive sessions; maturity attainable seven mo after hatching; longevity at least 4 yr and 5 mo; and a dramatic decline occurred in egg viability in successive generations in the laboratory.
The nervous system in the praesoma of Echinorhynchus salmonis (Acanthocephala: Echinorhynchidae)
Authors: Gee Randall J.
Published: February 2005

Based on light microscopic observations, nerve pathways are described for the first time in the praesoma of a species of the Echinorhynchidae. The pathways are described for 18 nerves, 8 paired and 2 single, which originate from the cerebral ganglion and a post‐ganglionic cell and terminate in the body wall musculature and the proboscis. The location of two commissures formed by these nerves is also described.
Sexually dimorphic laryngeal morphology in Rana pipiens
Authors: McClelland Blinda E. , Wilczynski Walter
Published: February 2005

The sexually dimorphic vocal characteristics of Rana pipiens release calls suggest that there may be differences in the anatomical components of the larynx. The volumes of the arytenoid cartilage, surrounding muscle masses, vocal cords, supporting bronchial process, and the release‐call amplitudes of six males and five females were measured in same‐sized animals and sexual differences assessed. No qualitative differences in laryngeal morphology were observed, but all features measured except vocal cords were significantly larger in males. The implications of an increased laryngeal size are discussed in relation to differences previously observed in the vocalizations of this and other species and in relation to prior suggestions regarding the developmental basis of anuran sexual dimorphisms.
Ontogeny of the skeleton of Spea bombifrons (anura: Pelobatidae)
Authors: Wiens John J.
Published: February 2005

The developing skeleton of a pelobatid frog, Spea bombifrons, is described based on a series of 81 cleared‐and‐stained tadpoles and juveniles. Most limb and limb‐girdle elements commence ossification premetamorphically, along with the parasphenoid, frontoparietals, exoccipitals, and vertebral column, during Gosner Stage 36. The chondrocranium undergoes dramatic restructuring at the beginning of metamorphosis (ca. Stage 40); and the nasal cartilages, prootics, premaxillae, nasals, maxillae, septomaxillae, and ischium appear. Near the end of metamorphosis (ca. Stage 44), the branchial arches are resorbed, the hyoid plate and quadrate form, and the angulosplenials, vomers, squamosals, dentaries, and pterygoids ossify. After metamorphosis (Stage 46), the laryngeal cartilages, sternum, omosternum, and plectral apparatus chondrify; and the carpals, tarsals, sphenethmoid, posteromedial hyoid processes, mentomeckelian bones, quadrates, columellae, and opercula ossify. The development of the fused sacrococcygeal articulation in S. bombifrons is described and compared to the more widespread bicondylar articulation. The presumed palatine bone and transverse processes of the coccyx are discussed, as are several seemingly paedomorphic skeletal features of Spea. Comparison with the sequence and timing of ossification in other anurans reveals that ossification of the skull and vertebral column occurs later in S. bombifrons than in other anurans; nonetheless, many aspects of the ossification sequence seem to be shared by a surprisingly wide range of anuran taxa.
Neuromast morphology and lateral line trunk canal ontogeny in two species of cichlids: An SEM study
Authors: Webb Jacqueline F.
Published: February 2005

A study of neuromast ontogeny and lateral line canal formation in Oreochromis aureus and Cichlasoma nigrofasciatum reveals the existence of two classes of neuromasts: those that arise just before hatching (presumptive canal neuromasts, dorsal superficial neuromasts, gap neuromasts, and caudal fin neuromasts) and pairs of neuromasts that arise on each lateral line scale lateral to each canal segment at the same time as canal formation. In the anterior trunk canal segment, each presumptive canal neuromast is accompanied by a dorsoventrally oriented superficial neuromast forming an orthogonal neuromast pair. It is suggested that each of these dorsoventrally oriented superficial neuromasts is homologous to the transverse superficial neuromast row described by Münz (Zoomorphology 93:73–86, '79) in other cichlids. It is further suggested that the longitudinal lines described by Münz (Zoomorphology 93:73–86, '79) are derived from the pair of superficial neuromasts that arise during canal formation. Distinct changes in neuromast topography are documented. Neuromast formation, scale formation, and lateral line canal formation are three distinct and sequential processes. The distribution of neuromasts is correlated with myomere configuration; there is always one presumptive canal neuromast on each myomere. A single scale forms beneath each presumptive canal neuromast. Canal segment formation is initiated with the enclosure of each presumptive canal neuromast by an epithelial bridge which later ossifies. The distinction of these three processes raises questions as to the causal relationships among them.
Structure and development of iridescent butterfly scales: Lattices and laminae
Authors: Ghiradella H.
Published: February 2005

Iridescent butterfly scales are structurally colored, relying upon the interaction of light with detailed architecture to produce their color. In some iridescent scales, the reflective elements are contained within the body of the scale and come in two basic forms, lattices that produce diffraction colors (analogous to those produced by opal), and stacks of laminae that produce thin‐film interference colors (analogous to those produced by soap or oil films). Both structures are remarkably complex and precise, yet each is only part of the total edifice built by the cell that makes the scale.

To understand better how a cell can produce lattices or thin‐film laminae, I studied the development of iridescent scales from two lycaenid butterflies. The presence of diffraction and thin‐film scales in the same family (and in some cases on the same individual) suggests that the two types must be developmentally related; yet these results yield no clear explanation as to how. The diffraction lattice appears to be shaped within the boundaries of the scale cell by means of a convoluted series of membranes in which the smooth endoplasmic reticulum plays an important part. The thin‐film interference laminae appear to result from the condensation of a network of filaments and tubes secreted outside the boundaries of the cell. This paper outlines the developmental histories of both types of scale and discusses the developmental implications of the mechanisms by which they form.