bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proximate developmental causes of limb length variation between Hyla cinerea and Hyla gratiosa (Anura: Hylidae)
Authors: Blouin Michael S. 
Published: February 2005

AbstractHyla 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

AbstractTesticular 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.
Neuromuscular organization of feline anterior sartorius: I. Asymmetric distribution of motor units
Authors: Thomson B. , Scott S. H. , Richmond F. J. R. 
Published: February 2005

AbstractThe neuromuscular organization of feline anterior sartorius was examined using three experimental approaches. First, the branching pattern of the nerve supplying anterior sartorius was inspected in muscles taken from a large number of feline cadavers. All muscles were found to be supplied by two major nerve branches, one directed proximally and the other directed distally, and most muscles (42/51) had a third distinct branch that entered the muscle centrally. Second, the motoneuronal populations supplying the three nerve branches were investigated by electrophysiological techniques. Motoneurons that supplied axons to the distally‐directed branch did not appear to have collaterals in more proximally‐located branches. In contrast, other motoneurons supplying the proximally‐directed branch also appeared to supply axon collaterals to the centrally‐directed branch. This result suggested that the motoneuronal population of the distally‐directed branch was largely separate from that supplying the proximally‐ and centrally‐directed branches. Third, the motor unit territories supplied by different nerve branches were mapped using glycogen‐depletion methods. Muscle fibers supplied by the distallydirected nerve branch were mostly distributed to the medial portion of anterior sartorius, whereas the fibers supplied by the other two branches were generally found more anteriorly. Further, the muscle fibers supplied by an individual nerve branch were present in greater numbers at the end of the muscle closest to the entry point of that branch. Thus, the motor units supplied by discrete nerve branches were found to be distributed asymmetrically within anterior sartorius, but were arranged neither strictly in‐parallel nor strictly in‐series.
Cell behavior during early development in the South American annual fishes of the genus Cynolebias
Authors: Carter C. A. , Wourms J. P. 
Published: February 2005

AbstractLiving embryos of three species of South American annual fishes, Cynolebias constanciae, C. nigripinnis, and C. whitei, were observed from fertilization through the 10‐somite stage. A description of normal stages of development applicable to all three species of Cynolebias is presented. Cleavage (stages 1–10) is meroblastic and produces a typical teleost blastoderm. Following cleavage (stages 11–13) blastomeres segregate into two populations, viz., (1) a population of deep blastomeres that will disperse as single motile cells, and (2) a hemispherical shell of outer blastomeres that flattens to form an enveloping cell layer (EVL). When epiboly of the EVL and the yolk syncytial layer (YSL) commences (stage 14), deep blastomeres clump together as a consolidation mass and then migrate outward as single cells on the YSL. When epiboly is concluded (stage 19), deep blastomeres have completely dispersed. If diapause does not intervene, the dispersed phase lasts only a few days. Subsequently, the dispersed cells come together to form a definitive aggregate (stage 27). Embryogenesis within the reaggregated mass of previously dispersed cells produces a typical teleost embryo.Early development in Cynolebias resembles that of other South American annual fishes, such as Austrofundulus, in that a phase of deep blastomere dispersion and reaggregation spatially and temporally separates epiboly from embryogenesis. Several features of development markedly differ from Austrofundulus. There are far fewer (250 vs. 2,500) deep blastomeres. Deep cells of Cynolebias are flattened rhomboids with filipodial extensions in contrast to the amoeboid cells of Austrofundulus. Blastomeres of dispersion and reaggregation stages in Cynolebias send out numerous cell surface extensions onto the YSL and in contact with one another, and often line up in rows as do some African annual fishes, e.g., Nothobranchius. During Dispersion II (stage 21), Reaggregation I (stage 22), and Reaggregation II (stage 23), deep cells move in an oriented pattern with respective mean velocities of 3.48 ± 0.91, 1.28 ± 0.46, and 1.31 ± 0.31 μm/minute. Cells move toward a granular mass of unknown composition, located at the YSL‐yolk interface in the lower hemisphere of the egg. This mass appears to coincide with the site of cell reaggregation.
Ovary of the golden crab, Chaceon fenneri: I. Post‐spawning and oosorption
Authors: Hinsch Gertrude W. 
Published: February 2005

AbstractOosorption has been considered an important strategy in many invertebrate species which occurs in response to behavioral, ecological, or physiological factors. In crustaceans, the early light microscopic studies of the ovary attributed a role in oosorption to follicle cells, hemocytes, or phagocytes. In this study, ovaries were collected from female golden crabs following spawning and processed for examination by electron microscopy.Following spawning, several unspawned oocytes which had become dissociated from their follicle cells were found in the ovaries. They appeared to be lodged within the lumen. Such oocytes were observed undergoing various stages of autolysis. At no time were hemocytes or recognizable phagocytes found in the lumen of the ovaries or in contact with the degenerating oocytes. Follicle cells which had surrounded the oocytes prior to the time of spawning exhibited disrupted membranes. Resorption of unspawned eggs appears to occur by autolysis of the individual oocytes.Several of the females who had recently spawned had numerous sperm in their ovaries. Such sperm may have been pressed into the lumen at the time of spawning or during the fixation process.
Oleospheres of the cave‐dwelling shrimp Troglocaris schmidtii: A unique mode of extracellular lipid storage
Authors: Vogt Günter , Štrus Jasna 
Published: February 2005

AbstractThe cave‐dwelling shrimp, Troglocaris schmidtii, has a unique mode of lipid storage. The lipid lies extracellularly in specialized compartments of the hepatopancreas, named oleospheres. The lipid is synthesized in the R‐cells of the hepatopancreatic epithelium and accumulates in lipid droplets which fuse to form bigger globules. Mature lipid globules display moderately electron dense centers probably comprising triglycerides, and a broad electron dense boundary presumably consisting of lipoproteins. The globules are discharged into the lumen of the hepatopancreatic tubules by a kind of apocrine secretion. There, they coalesce to form larger masses. Finally, these lipid masses are transported into the oleospheres through a valve‐like structure. The continual accumulation of lipid results in a drastic expansion of the oleospheres up to 500 μm in diameter. The absence of food in the digestive tract and the inactivity of the digestive enzyme producing F‐cells indicate that digestion is suspended in the period of oleosphere formation. The curious mode of lipid storage in T. schmidtii may represent an adaptation to the extreme environmental conditions of a cave.
Comparative anatomy and phylogeny of the cloacae of salamanders (amphibia: Caudata). III. Amphiumidae
Authors: Sever David M. 
Published: February 2005

AbstractHistological descriptions of female and male cloacae are presented for the three species of Amphiuma. Little interspecific variation occurs in either females or males. Females possess numerous spermathecae around the walls of the posterior cloacal tube and anterior cloacal chamber as well as rudimentary vent glands, of uncertain homology, in the caudal end of the cloacal chamber. Ventral glands such as those known from female salamanders in other families are absent, likely a secondary loss in the amphiumid clade. In a female A. tridactylum with large ovarian follicles (5‐ to 8‐mm diameter), the lips of the cloacal orifice are highly cornified, and stored sperm in the spermathecae appear in organized bundles, either free in the lumen or with the sperm heads seemingly buried in the spermathecal epithelium. Males possess some gland clusters present in other members of the suborder Salamandroidea (dorsal pelvic glands, vent glands, Kingsbury's glands, anterior ventral glands) but lack others (lateral pelvic glands, posterior ventral glands), resulting in the most plesiomorphic cloacal anatomy in the suborder. However, males possess an autapomorphic gland cluster, called the pit glands, in the posterior wall of the cloacal chamber. The pit glands consist of shallow infoldings of the cloacal epithelium unlike other cloacal glands, which are relatively tubular and elongate. The “pits” contain columnar eosinophilic cells that give positive staining reactions for acid mucopolysaccharides and proteins.
Pigment pattern formation in larval ambystomatid salamanders: Ambystoma tigrinum tigrinum
Authors: Olsson Lennart , Löfberg Jan 
Published: February 2005

AbstractWe have begun a comparative study of pigment patterns and their mechanisms of formation in ambystomatid salamanders in an attempt to elucidate the evolution of these traits in this family. In Ambystoma t. tigrinum, the migration of the prospective pigment cells was followed by using scanning electron microscopy and light microscopy combined with markers (dopa incubation for detecting melanophores, ammonia‐induced pterin fluorescence for detecting xanthophores). The pigment pattern resulting from the cell migration shares features both with the alternating vertical xanthophore and melanophore bars of A. mexicanum and the horizontal stripes of certain salamandrids and ambystomatids. The pigment pattern of A. t. tigrinum is interpreted here as an intermediate evolutionary step between a primitive horizontal stripe pattern and a derived vertical bar pattern. The initiation of pigment pattern formation resembles the situation in A. mexicanum, probably reflecting the close phylogenetic relationship between the two taxa.
Fine structure of the dorsal epithelium of the tongue of the freshwater turtle, Geoclemys reevesii (Chelonia, Emydinae)
Authors: Iwasaki Shin‐Ichi 
Published: February 2005

AbstractScanning electron microscopy shows that lingual papillae occur all over the dorsal surface of the tongue of the freshwater turtle, Geoclemys reevesii. The surface of each papilla is composed of compactly distributed hemispherical bulges, each composed of a single cell. Microvilli are widely distributed over the surface of cells. Histological examination reveals that the connective tissue penetrates deep into the center of papillae and that the epithelium is stratified columnar. Under the transmission electron microscope, the cells of the basal and the deep intermediate layers of the epithelium appear rounded. A large nucleus lies in the central area of each cell. The cytoplasm contains mitochondria, endoplasmic reticulum and free ribosomes. The cell membrane form numerous processes. The shallow intermediate layer contains two types of cell. The cytoplasm of the first has numerous fine granules, in addition to mitochondria, ribosomes, and endoplasmic reticulum. The other type of cell contains highly electron‐dense granules. The surface layer shows two cell types. One type consists of typical mucous cells. The other type of cell contains fine, electron‐lucent granules. The latter cells lie on the free‐surface side, covering the mucous cells, and have microvilli on their free surfaces.
Trunk movements during locomotion in the marsupial Monodelphis domestica (didelphidae)
Authors: Pridmore Peter A. 
Published: February 2005

AbstractThe small didelphid cmarsupial, Monodelphis domestica, uses a lateral sequence walk during slow treadmill locomotion and gradually shifts to a trot as speed increases. At higher speeds it changes abruptly to a half‐bound. Cinematographic records suggest significant lateral bending but no sagittal bending of the trunk during the slow walk and a reduced amount of lateral bending during the fast walk. There is slight lteral, but no sagittal, bending during the trot. Sagittal bending is obvious during the half‐bound, but no lateral bending is evident. Cineradiography confirms that the vertebral column of the trunk bends laterally during the slow walk. Bending occurs throughout the trunk region, but seems to be most pronounced in the anterior lumbar region. Associated with this bending of the trunk is substantial rotation of the pelvic girdle in the plane of yaw. Pelvic rotation is synchronized with the locomotor cycle of hindlimbs. Each side of the pelvis rotates forward during the recovery phase of the ipsilateral hindlimb and backward during the contact phase of this limb. Information on locomotor trunk movements in other limbed tetrapods is limited. The pattern of trunk bending found in Monodelphis, however, is consistent with that reported in the placental mammal Felis catus and in some lepidosaurian reptiles. This suggests that sagittal bending did not replace lateral bending during the evolution of mammals, as is sometimes suggested. Rather, bending in the vertical plane seems to have been added to lateral bleeding when the ancestors of extant mammals acquired galloping and bounding capabilities.
Morphology and glycoconjugate histochemistry of the palpebral glands of the adult newt, Notophthalmus viridescens
Authors: Reyer Randall W. , Liou Willisa , Pinkstaff Carlin A. 
Published: February 2005

AbstractThe eyelids of the newt were studied in 10 μm serial paraffin and 1–2 μm plastic sections using standard histological stains and special stains for glycconjugates. The eylids contain four different glands. Simple acinar serous and simple acinar mucous glands occur in the skin; unicellular mucous glands occur in the conjunctiva; and convoluted tubular seromucous glands are present in connective tissue beneath the conjunctiva. The first two are identical to cutaneous glands found elsewhere on the head and body. The simple acinar serous glands are surrounded by myoepithelial cells and release their sectetion, which is composed largely of proteins with minimal glycoconjugate content, by a holocrine mechansm. The secretory product of the simple acinar mucous glands is composed of neutral glycoconjugates with a minor content of acidic glycoconjugates; the mucin exhibits strong PAS and PAPD staining and weak staining by AB and PAPS methods. The unicellular conjunctival mucous glands secrete both neutral and acidic glycoconjugates as shown by positive reactions with PAS, PAPD, PAPS, and AB methods. Convoluted tubular seromucous glands in the ventral eyelid synthesize both proteins and neutral glycoconjugates. The mucous secretions of the conjunctival glands probably provide lubrication and protection for the cornea.
Spermatozoon structure of eight species of South African holothurians (Echinodermata)
Authors: Hodgson A. N. , Bernard R. T. F. 
Published: February 2005

AbstractTransmission electron microscopy of the spermatozoa of eight species (from seven genera) of holothurians has shown that each species has a sperm with unique dimensions, indicating that spermatozoon morphology can be used as a taxonomic character. However, although the structure of the sperm is species‐specific, all sperm have a similar appearance which is typical of holothurians. The sperm head is composed of a spheroidal nucleus (about 2 μm diameter) which has a large anterior fossa housing the approximately spherical acrosome. The acrosome is differentiated internally and surrounded by periacrosomal material. The mid‐piece consists of a single mitochondrion with lamellar cristae which surrounds the eccentrically positioned centrioles. The conservative form and arrangement of the sperm organelles suggest that sperm morphology cannot be used for phylogenetic investigations within this taxon.
Ultrastructure of otolith increments and checks in the teleost fish Oreochromis niloticus
Authors: Zhang Z. 
Published: February 2005

AbstractAn otolith increment is composed of an incremental zone and a discontinous zone. Observation of the otoliths of Oreochromis niloticus with transmission and scanning electron microscopy reveals that organic fibers are concentrated in the discontinuous zone and are relatively scarce in the incremental zone. On the other hand, calcium carbonate crystals are chiefly packed in the incremental zone and are less dense in the discontinuous zone. Both fibers and crystals are oriented perpendicular to the growth increments. Otolith checks, or discontinuities, contain even denser fibers and fewer fine crystals than does the discontinuous zone. A higher proportion of individual fibers is prominently stained in the discontinuous zone and check than in the incremental zone. Other features of individual fibers appear to be the same among the three zones. The crystals on either side of a check or a discontinuous zone resemble each other both in size and orientation. Zonation of protein and mineral components of otoliths can be understood in terms of both incremental growth and the daily cycle of deposition.
Development of the subdigital adhesive pads of Ptyodactylus guttatus (Reptilia: Gekkonidae)
Authors: Rosenberg Herbert I. , Russell Anthony P. , Cavey Michael J. 
Published: February 2005

AbstractSubdigital adhesive pads play an important role in the locomotion of many species of gekkonid lizards. These pads consist of integrated components derived from the epidermis, dermis, vascular system, subcuticular tendons, and phalanges. These components become intimately associated with each other during the developmental differentiation of the digits and the sequence of this integration is outlined herein in Ptyodactylus guttatus. The pads initially appear as paired swellings at the distal tips of the digits. Subsequently, a fan‐like array of naked scansors develops on the ventral surface of each digit, at about the same time that scales differentiate over the surface of the foot as a whole. At the time of appearance of the naked scansors, the vascular sinus system of the pad also differentiates, along with subcuticular connective tissue specializations. At this stage the digits, along with the rest of the body, are clad in an embryonic periderm. Only after hatching and as the periderm is shed, do the epidermal setae and spines appear. The developmental sequence described here is consistent with predictions previously advanced about the evolutionary origin and elaboration of subdigital pads in gekkonid lizards. The paucity of available staged embryonic material leaves many questions unresolved.
Relationship of saccular ultrastructure to otolith growth in the teleost Oreochromis niloticus
Authors: Zhang Z. 
Published: February 2005

AbstractThe sacculus of Oreochromis niloticus is anatomically separated from the utriculus and semicircular canals. The saccular wall is composed of the sensory epithelium, transitional epithelia, and squamous epithelium. Cellular granules are abundant in the sensory and transitional epithelia but scarce in the squamous epithelium. Over the dorsal side of the dorsal transitional epithelium there exists an oval patch of cells with distinctive microvilli. New finding is a shallow groove which extends from the anterior end of the sensory epithelium approximately halfway down along the ventral perimacular transitional epithelium. Small vesicles, which appear “empty” under transmission electron microscopy (TEM), are aggregated in the posterior region of the groove. These small vesicles are also present in both the sensory and transitional epithelia. A second kind of vesicle is comparatively large and appears filled with stainable contents. These vesicles are restricted to the sensory region. Both kinds of vesicles appear to be involved in apical secretion and possibly provide the otolithic membrane with fibers. The otolithic membrane is composed of a gelatinuous layer and subcupular meshwork. The meshwork appears to contribute to the formation of the otolith. The small empty vesicles appear to originate in sensory and transitional epithelial cells and may form the subcupular meshwork. The larger filled vesicles are derived predominantly from sensory cells in the sensory epithelium and appear to contribute to the gelatinuous layer of otoliths. © 1992 Wiley‐Liss, Inc.