bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unusual cuticle‐associated organs in the heterotardigrade, Echiniscus viridissimus
Authors: Dewel Ruth Ann , Dewel William C. , Roush Brenda G. 
Published: February 2005

AbstractEchiniscus viridissimus possesses two organs that lie above the ventromedial body wall approximately at the level of the second and third pair of legs. Each organ is composed of one medial and two lateral cells and possesses a pair of convoluted ducts. The lateral cells produce and release profuse amounts of filamentous basement membrane‐like material into the body cavity. The proliferated material persists en masse adjacent to the lateral cells and is associated with disrupted droplets of pigmented body cavity material (BCM). The medial cell is larger than the lateral cells and possesses numerous tubular invaginations in which droplets of BCM are frequently found. Each duct originates as an infold that becomes a simple channel in the lateral cell and continues through the medial cell in a deep groove covered by a long process of the lateral cell. Although the ducts lie on the medial cell surface, they are “internalized” at the base of deep clefts and isolated from the body cavity by “tight” zonulae adherentes junctions. In the medial cell the ducts have a cuticle‐like lining and the associated plasma membrane is characterized by numerous saccular infolds containing flocculent material. The duct linings, which extend beyond the limits of the medial cell, project into the endocuticle and terminate on the lateral body wall. Because the lateral cells are producing and releasing profuse basement membrane and because material with an electron density similar to BCM is present in the saccules, the distal regions of the ducts and in the endocuticle, we propose (1) that the lateral cells are producing basement membrane to disassociate BCM and (2) that the medial cell is absorbing and via its ducts translocating that BCM to the endocuticle. Furthermore, because the medial cell exhibits characteristics of transporting epithelia, namely numerous tubular infolds of the outer surface, a layer of distended saccules surrounding the duct and a high density of mitochondria, we suggest that the medial cell also functions in ion or osmotic regulation. © 1992 Wiley‐Liss, Inc.
Morphology of the reproductive tract in a lizard exhibiting incipient viviparity (Sphenomorphus fragilis) and its implications for the evolution of the reptilian placenta
Authors: Guillette Louis J. 
Published: February 2005

AbstractThe morphology of the female reproductive tract and corpus luteum is examined in Sphenomorphus fragilis, a lizard from the lowland regions of New Guinea exhibiting incipient viviparity. Females oviposit eggs that hatch either immediately or within a few hours. Corpora lutea form from ovulated follicles and decrease in diameter as embryonic development progresses. The oviduct from vitellogenic females is sparsely populated with well developed uterine glands containing secretory granules. The eggs are covered with a relatively thin shell (10 μm thick) composed of an inner boundary layer and proteinacous fibers. The secreted shell is complete by early neurulation. Shell morphology does not change throughout the remainder of the in utero incubation period. A well vascularized uterus and chorioallantoic membrane provide simple placentation. These findings suggest that the reduction in shell thickness associated with the evolution of a placenta is due to a decrease in the number of shell glands in the uterus and is not a delay or inhibition of the shelling process per se. This hypothesis further suggests that the selective forces favoring shell gland loss act on the vitellogenic female during gland recruitment which occurs prior to ovulation and not on the pregnant female. © 1992 Wiley‐Liss, Inc.
Histology of the esophagus of the adult frog Rana perezi (Anura: Ranidae)
Authors: Gallego‐Huidobro J. , Pastor L. M. , Calvo A. 
Published: February 2005

AbstractStudy of the esophageal microscopic morphology of adult Rana perezi by light and electron microscopy discloses some large folds throughout the esophagus that are in themselves ringed. Glandular ostia open in the furrows of the luminal surface. The esophageal wall is made up of a connective adventitia rich in melanocytes, a muscular tunica, a connective and glandular subepithelial layer, and a pseudostratified ciliated epithelium. This epithelium basically consists of ciliated, goblet, basal, microvillous‐apex, and migratory cells. Two types of goblet cells are distinguished with regard to the granular ultrastructure. The microvillous‐apex cell has not been found in other amphibians. It shows a very differentiated morphology with a high number of mitochondria. The basal cells give the epithelium a pseudostratified morphology, and they have a proliferative function. Glands are branched and drain through an excretory duct that has a monolayered mucosecreting epithelium. The glandular units are formed by two principal types of cells: mucosecretory and serous. © 1992 Wiley‐Liss, Inc.
Middle‐ear development: II. Morphometric changes in the conducting apparatus of the chick
Authors: Cohen Yale E. , Hernandez Hector N. , Saunders James C. 
Published: February 2005

AbstractThe ontogeny of various middle‐ear structures was examined in 11 groups of chicks between 10 days embryonic and adult. Measurements of the tympanic membrane surface area and height, columella length, and that of the columella footplate, annular ligament, and oval window area were obtained using video micrographs and computer digitization techniques. The oval window matures first at 53 days post‐hatching, whereas the columella achieves adult size at 74 days. The tympanic membrane surface area is the last middle‐ear variable studied to reach adult size (79 days post‐hatch). The columella increases its length from 0.63 mm (10 days embryonic) to 2.73 mm in the adult. The tympanic membrane area expands by 280% whereas the columellar footplate area increases by 11x. As a result, the pressure amplification of the middle ear due to the tympanic membrane/columellar footplate area ratio improves by over 400%. These data further contribute to our understanding of the functional development of the middle ear. © 1992 Wiley‐Liss, Inc.
Four forearm flexor muscles of the horse, Equus caballus: Anatomy and histochemistry
Authors: Hermanson John W. , Cobb Matthew A. 
Published: February 2005

AbstractTwo of the forearm flexors of the horse, the superficial and deep digital flexor muscles, are critical to support the digital and fetlock joints, exhibit differing insertions, and are passively supported by the proximal and distal check ligaments, respectively. These two muscles differ in histochemical composition and architecture. The differences are correlated with the different stress levels transmitted through their tendons, and the different frequencies of clinical breakdown that have been reported. Both muscles contain type I and type IIa fibers. A few type IIb fibers occurred in the deep digital flexor. The superficial digital flexor contained approximately 56% type I fibers, extremely short muscle fibers, and extensive connective tissue investment. In contrast, the deep digital flexor had three muscle heads: ulnar, radial, and “long” and “short” regions of the humeral head. The “long” and “short” regions of the humeral head contained 33% and 44% type I fibers, respectively, fiber lengths three to four times as long as those in the superficial digital flexor, and relatively less connective tissue investment. Flexor carpi radialis and flexor carpi ulnaris compared most closely with the humeral head of the deep digital flexor. These data suggest a correlation of the unique architecture of superficial digital flexor with its proposed elastic storage properties during locomotion in horses, and an explanation for the frequent breakdown of the superficial digital flexor in athletic horses. © 1992 Wiley‐Liss, Inc.
Spermiophagy by the spermathecal epithelium of the salamander Eurycea cirrigera
Authors: Sever David M. 
Published: February 2005

AbstractThe spermathecae of Eurycea cirrigera are exocrine glands in the cloaca that secrete a substance that bathes sperm stored in the lumen after mating and prior to oviposition. Many sperm remain in the spermathecae after oviposition, and the spermathecal epithelium becomes spermiophagic. Pseudopodia enclose sperm into endocytic vacuoles. The vacuoles become associated with primary lysosomes in the cytoplasm. Following formation of secondary lysosomes and resulting condensation of the sperm fragments, residual bodies are exocytized into the surrounding connective tissue stroma. By the start of the next breeding cycle, most sperm remaining from the previous mating have been degraded, but some sperm remain in the lumen, and the viability of these sperm is unknown. © 1992 Wiley‐Liss, Inc.
Seminal receptacula in the female reproductive tract of Opisthopatus cinctipes purcell (onychophora, peripatopsidae)
Authors: Walker Muriel H. 
Published: February 2005

AbstractThe presence of seminal receptacula in the female reproductive tract of Opisthopatus cinctipes (Purcell, 1900) has been disputed (Choonoo, '47; Ruhberg, '85; Herzberg et al., '80). However, they do occur and are described here from observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). No spermatozoa are associated with the surface of the ovary; in contrast the ovary of Peripatopsis capensis is covered with spermatozoa and numerous small rounded cells. The seminal receptacula of O. cinctipes are formed from a loop in the proximal region of the uterus and contain remnants of spermatozoa in their lumens. The epithelial cells lining the seminal receptacula contain numerous vesicles and residual bodies. It is suggested that these cells absorb those spermatozoa not required for fertilization, and that the seminal receptacula in the Peripatopsidae act as short‐term storage sites for spermatozoa. By contrast, the seminal receptacula of the Peripatidae are considered to act as long‐term storage sites for spermatozoa. © 1992 Wiley‐Liss, Inc.
Video‐enhanced microscopy of organelle movement in an intact epithelium
Authors: Karnaky Karl J. , Garretson Leon T. , O'Neil Roger G. 
Published: February 2005

AbstractDigitally enhanced video microscopy has provided improved optical resolution in the study of intracellular organelle/particle movement, particularly in extruded axoplasm and certain thin single cell systems. We report here, for the first time, particle movement in an intact, isolated epithelium, the killifish proximal convoluted tubule. Cytoplasmic particles exhibited predominately unidirectional linear movement approaching several microns in length, sometimes with multiple turns. The velocities of 34 particles measured in 11 cells averaged 0.29 μm/sec (range, 0.007–3.1 μm/sec). Microtubules—the well‐established basis for organelle movement in cells—were present but were sparsely represented in electron micrographs of these cells. Video‐enhanced microscopic techniques can now be applied to the study of organelle/particle movement in an intact epithelium. © 1992 Wiley‐Liss, Inc.
Retinoic acid enhances monoclonal antibody WE3 reactivity in the regenerate epithelium of the adult newt
Authors: Tassava Roy A. 
Published: February 2005

AbstractMonoclonal antibody (mAb) WE3 recognizes an antigen that is developmentally expressed in the wound epithelium during adult newt limb regeneration. Experiments were designed to determine whether retinoic acid (RA), dissolved in dimethyl sulfoxide (DMSO) and administered by intraperitoneal injection, would enhance the temporal appearance of the WE3 antigen. RA given on days 1 or 4 after amputation, when the WE3 antigen is not yet detectable, resulted in moderate reactivity to mAb 2 days after injection and strong reactivity throughout the wound epithelium 4 days after injection. DMSO alone had no enhancing effect. RA also caused limb skin epidermis to exhibit reactivity to mAb WE3, initially near the amputation level, but then also more proximally. By 4 and 6 days after RA injection, epidermis of the flank, eye lid, and unamputated hind limbs also became strongly reactive to mAb WE3. Outer layers of skin epidermis were shed, resulting in an epidermis only one or two cells thick. Epidermis of newts given DMSO alone remained non‐reactive to mAb WE3. When RA was given on days 7 and 10 after amputation, when a low level of mAb WE3 reactivity is already present in the wound epithelium, a considerable enhancement of mAb WE3 reactivity occurred through the next few days. No such enhancement was seen with DMSO alone. RA also greatly increased mAb WE3 reactivity in the wound epithelium of denervated limbs, in which case the wound epithelial reactivity to mAb WE3 is normally low. Retinol palmitate also increased mAb WE3 reactivity. The results raise the possibility that the WE3 antigen is a component of most if not all retinoid target tissues in newts. © 1992 Wiley‐Liss, Inc.
Neuromuscular organization of feline anterior sartorius: II. Intramuscular length changes and complex length‐tension relationships during stimulation of individual nerve branches
Authors: Scott S. H. , Thomson D. B. , Richmond F. J. R. , Loeb G. E. 
Published: February 2005

AbstractThe feline anterior sartorius is a long strap‐like muscle composed of short muscle fibers. Nerve branches that enter this muscle contain the axons of motor units whose constituent muscle fibers are distributed asymmetrically within the muscle. In the present study, twitch and tetanic isometric contractions were evoked by stimulating individual nerve branches while muscle force was recorded and intramuscular length changes were monitored optically by the movement of reflective markers on the muscle. Contractions elicited by stimulating the parent nerve produced little change in the positions of the surface markers. Contractions elicited by stimulating the proximally or distally directed nerve branches caused the muscle to shorten at the end closest to the nerve branch and lengthen at the opposite end. Some muscles were supplied by a centrally directed nerve branch whose stimulation produced variable effects: in some cases a portion of the muscle shortened whereas the rest lengthened, but in other cases, the positions of the surface markers showed little change. The intramuscular length changes produced by stimulating single nerve branches were greater during isometric contractions at short whole‐muscle lengths than at long whole‐muscle lengths. The twitch and tetanic length‐tension relationships obtained by stimulating the individual nerve branches were not congruent with the length‐tension relationship produced when the parent nerve was stimulated. At short whole‐muscle lengths, stimulation of a single nerve branch generated only a small fraction of the force that could be generated by the muscle when the parent nerve was stimulated. As whole‐muscle length increased, an increased fraction of total muscle force could be generated by stimulating a single nerve branch. The results suggest that a complex relationship between passive and active elements contributes to the total muscle force and depends on the distribution of active and passive muscle units throughout the muscle. © 1992 Wiley‐Liss, Inc.
Visual demonstration of the limb‐forming zone in the chick embryo lateral plate
Authors: Stephens Trent D. , Sanders Duane D. , Yap Clementine Y. F. 
Published: February 2005

AbstractThe present study was undertaken to determine whether a visible Wolffian ridge, distinct from the lateral fold, can be identified in chick embryos. Ectoderm thickness was measured in stage 11–17 chick embryos. There was a general trend, from thin ectoderm in the midline, to an ectodermal thickening over the somites, intermediate mesoderm, and lateral plate. Other embryos were cut from the yolk, pinned out, and photographed. The lateral fold was then eliminated, and the embryo was rephotographed. The photographs reveal a definite opaic zone, distinct from the lateral fold, in stage 11–18 chick embryos. Furthermore, there is a direct correlation between the opacity of this cellular band and the limb‐forming potential of grafted wing, flank, and leg regions (see Stephens et al., '89). At stages 11–14, the wing, flank, and leg exhibit a uniform opacity, and a uniform capacity for limb formation when grafted to a host celom. From stage 15 to stage 18, the opacity in the flank diminishes, and its limb‐forming capability disappears. This study demonstrates the presence of an opaic zone, which we have called the limb‐forming zone (LFZ) along the lateral side of early chick embryos, which is independent of the lateral fold, is not as extensive as the lateral plate, and is not simply associated with ectodermal thickening, but which is directly correlated with limb‐forming potential in the lateral plate. © 1992 Wiley‐Liss, Inc.
Vertebral development of the chick embryo during days 3–19 of incubation
Authors: Shapiro Frederic 
Published: February 2005

AbstractChick embryo vertebral development has been studied during the period from 3 to 19 days of incubation. Whole mount preparations stained with alcian blue for cartilage and alizarin red for bone show the vertebral bodies as cartilaginous at 5 days, with dorsal spinous processes at 6½ days, the onset of bone formation at the ventral and dorsal surfaces of the bodies at 13 days, ossification extending dorsally within the neural arches at 13½ days, and bone development occurring throughout the vertebrae at 16 days. Descriptions at each time period center on the thoracic vertebrae with occasional inclusion of adjacent lower cervical and upper lumbar vertebrae. Histologic development is correlated with the Hamburger‐Hamilton stages, which are based on external characteristics. The notochord and neural tube are well developed by 3 days and surrounded by sclerotome, myotome, and dermatome cells. Cartilage formation in the perinotochordal region of the vertebral body is seen at 5 days and precedes development of the neural arches and spinous processes. Separate centers of chondrocyte hypertrophy occur in the body (9 days), the lateral neural arches and the dorsal spinous process. Bone formation is under way at 13 days, beginning in the vertebral bodies. Intramembranous periosteal bone formation is seen adjacent to internal regions of chondrocyte hypertrophy. Vascular invasion of hypertrophic chondrocyte regions occurs, but the mechanism of endochondral ossification differs from that of mammals. The cartilage is resorbed by multinucleated chondroclasts and marrow round cells. Clumps of growth plate cartilage cells and matrix are surrounded occasionally by newly synthesized bone, but invasion of individual hypertrophic chondrocyte lacunae by vessels with bone deposition by accompanying osteoblasts on single trabeculae of cartilage does not occur. 3H‐thymidine autoradiography shows high uptake at 3 and 5 days in the germinal neuroepithelial cells of the neural tube (spinal cord) and notochord. By 7 days, notochordal uptake is markedly diminished, and no uptake of isotope occurs from 8 days onward. Spinal cord uptake is highest in the first 8 days but persists in lessened amounts to 19 days. From 5 days onward, both undifferentiated mesenchymal cells and differentiated chondrocytes show positive 3H‐thymidine uptake, but labeling is never seen in hypertrophic chondrocytes. © 1992 Wiley‐Liss, Inc.
Gill raker structure and development in indo‐pacific anchovies (Teleostei: Engrauloidea), with a discussion of the structural evolution of engrauloid gill rakers
Authors: Bornbusch Alan H. , Lee Melinda 
Published: February 2005

AbstractThe postlarval development of gill raker denticles is described for the engrauloid (anchovy) genera Coilia, Lycothrissa, Setipinna, Thryssa, Stolephorus, and Encrasicholina based on scanning electron microscopy. The raker structure of adult Papuengraulis is also described. In the coiliid genera Coilia, Lycothrissa, Setipinna, Thryssa, and Papuengraulis, denticle development is not confined to particular region(s) of the raker. With few exceptions, the proliferation of denticles with growth is greatest along the upper raker edge; denticles are smaller and less dense on the raker faces and along the lower raker edge. Some Thryssa and Setipinna have a derived condition of denticle clustering along the upper raker edge. In Stolephorus and Encrasicholina, denticle development is confined to the upper raker half and includes the development of a single row of denticles along each raker face. A phylogenetic analysis of engrauloid raker structure, incorporating data from Bornbusch ( 88: Copeia 1988:174–182) and based on outgroup comparisons, indicates that for the Engrauloidea: (1) the pattern of denticle development shared by coiliids is plesiomorphic; and (2) the pattern of denticle development shared by Stolephorus, Encrasicholina, and most other engraulids is synapomorphic for the Engraulidae. There is no evidence that the studied coiliids Stolephorus and Encrasicholina are suspension feeders. The engraulid pattern of raker denticle development which is retained in suspension feeding engraulids of the genus Engraulis was thus derived before the derivation of suspension feeding in Engraulis. Comparative morphological and phylogenetic studies of clupeomorph raker structures and feeding behaviors can infer the historical origins of morphology‐behavior associations, help define possible directions for analyses of raker denticle function, and thereby help elucidate the significance of structure‐function couplings in the evolution of such clupeomorph trophic behaviors as suspension feeding. © 1992 Wiley‐Liss, Inc.
Cytoplasmic droplets of painted turtle spermatozoa
Authors: Gist Daniel H. , Hess Rex A. , Thurston Ronald J. 
Published: February 2005

AbstractEpididymal sperm from the painted turtle (Chrysemys picta) possess a cytoplasmic droplet which is located eccentrically on the sperm midpiece. The droplet contains a large quantity of lipid droplets in addition to hollow vesicles and degenerate mitochondrial fragments. Lipid droplets are closely associated with mitochondrial membranes and may function in the formation or degradation of mitochondria. Cytoplasmic droplets become detached from the sperm midpiece in a coordinated manner shortly before the commencement of fall mating and are not observed on sperm recovered from the oviduct of females. © 1992 Wiley‐Liss, Inc.
Malpighian tubules of Formica polyctena (Hymenoptera): Light and electron microscopic study
Authors: Garayoa M. , Villaro A. C. , Montuenga L. , Sesma P. 
Published: February 2005

AbstractThe study of semithin (1 μ in thickness) and thin sections of Epon‐embedded material reveals that Malpighian tubules of Formica polyctena are composed of a single cellular type throughout their length. No differentiated regions were observed. Ultrastructural traits of the epithelial cells are those of highly metabolic cells engaged in water and ion transport: large euchromatic nucleus, several nucleoli, abundant mitochondria, a conspicuous brush border, and basolateral infoldings. Lysosomes, smooth endoplasmic reticulum, and intercellular junctions are also well developed. Mineral concretions occur within the cells and in the lumen. However, the degree of development of these cytological traits is variable among the different cells. The tubules drain into the gut through a specialized posterior region of the midgut or ampulla. In this region, the epithelial cells, although usually taller and showing conspicuous basal infoldings, display cytological structures similar to those of the Malpighian tubules. © 1992 Wiley‐Liss, Inc.