bluuebunny/crossref_metadata_2025_split huggingface dataset:
The nasal gland of the Montpellier snake Malpolon monspessulanus: Fine structure, secretion composition, and a possible role in reduction of dermal water loss
Authors: Dunson William A. , Dunson Margaret K. , Keith Alec D. 
Published: June 2005

AbstractA study was made of the structure and function of the enlarged lateral nasal gland of the Montpellier snake (Malpolon monspessulanus). This unusual gland opens directly to the exterior via a duct on the nasal valve. The secretion is spread over the skin surface by a series of stroking movements with the head. An ultrastructural examination showed that the gland does not have the specialized cytological features associated with salt secretion, the only previously known function for nasal glands in reptiles. The principal tubule cells are filled with clear secretory vacuoles of various sizes, moderate numbers of mitochondria, and have few interdigitations with adjacent cells. The nuclei are basal. In one snake the cells had numerous membrane bound lamellar bodies (LB) in the basal region. These LB stained darkly with toluidine blue and strongly resembled lamellar bodies found in the mammalian lung. Although LB were not seen in nasal glands of five other snakes, membrane bound globular structures found in some might well be earlier or later stages of the same organelle, possibly a lysosome. A major portion of the gland is a system of anastomosing ducts lined with simple columnar or cuboidal epithelium. The ducts not only connect with the secretory tubules but also with blind vessels lined with squamous epithelium. The glands go through cyclic increases in size, which are externally visible as swellings posterior to the nares. Gentle pressure on the swollen glands expelled fluid through the duct on the exterior aspect of the nasal valve. At certain times the glands also responded to subcutaneous injections of the parasympathetic agent pilocarpine by pronounced swelling. The secretion was quite watery but contained a complex mixture of fatty acids, proteins, and variable amounts of sodium and potassium. The spreading of this material over the skin might be related to retardation of dermal evaporative water loss, since long chain fatty acids are known to have this effect when applied as films on an aqueous surface. In partial confirmation of this hypothesis, rates of total evaporative water loss were found to be extremely low (0.2–0.5% body weight/day for 0.2–1.0 kg snakes at 33°C). In dry air at 33°C, the dermal loss was only about 30% of the total evaporative loss.
A comparison of lactate dehydrogenase isozymes in tissues of immature and mature Coho salmon (Oncorhynchus kisutch)
Authors: Márquez Ernest D. 
Published: June 2005

AbstractLactate dehydrogenase (LDH) isozymes from various tissues of mature and immature (fry) Coho salmon (Oncorhynchus kisutch) were compared. Brain isozymes from both appeared identical while minor differences were seen with isozymes from liver and heart. The most dramatic differences were observed in isozymes from muscle. Adult muscle displayed 8 discernible LDH isozymes while fry muscle displayed 7. Of these, fry muscle contained 2 predominant isozymes, one of which was specified by the B locus while the other was specified by the A locus. In adult muscle 3 predominant isozymes were seen and all were A locus associated. In addition, none of the predominant isozymes from adult and fry muscle were seen to comigrate.
Epidermal regeneration and percutaneous water loss following cellophane stripping of reptile epidermis
Authors: Maderson P. F. A. , Zucker A. H. , Roth S. I. 
Published: June 2005

AbstractThe histological and physiological effects of the removal of superficial corneous epidermal materials have been studied in several squamate species and a caiman.The gross and microscopic anatomy of the squamate integument has characteristics which make cellophane stripping inherently variable, but in general, when corneous materials are removed, they are replaced over a period of one to two weeks, by a tissue with the histological characteristics of the normal α‐layer. This tissue may be produced by stimulated germinal activity and/or metaplasia of other presumptive cell populations.In caiman, the thickness of the corneous tissues of the outer scale surface is reduced by stripping and the tissue is restored to normal in approximately two weeks by stimulated germinal proliferation.Measurements of cutaneous water loss (CWL) before, immediately after, and during two weeks post‐trauma revealed the following. There is a sudden rise in CWL immediately after stripping, and values decline over the next two weeks as the corneous tissues are replaced.The results are interpreted as indicating that, as in mammals, the impermeability of the epidermis depends on the thickness of the corneous materials. In squamates it appears that the physiological barrier is the αlayer of the epidermal generation, and while the β‐layer cannot be excluded as playing some role in reducing the permeability of the integument, its role appears to be primarily mechanical.
Alterations in growth, function and composition of Rana pipiens oocytes and follicles associated with microsporidian parasites
Authors: Schuetz Allen W. , Selman Kelly , Samson Douglas 
Published: June 2005

AbstractA class of unique, abnormally enlarged and discolored follicles and oocytes were identified in ovaries of sexually mature Rana pipiens. Various parameters of the composition, function and structure of these “large” oocytes were analyzed and compared to that of normal, fully grown oocytes and follicles obtained from the same ovary. Large oocytes in contrast to normal oocytes contained markedly elevated concentrations of potassium and decreased levels of calcium ions. Sodium and magnesium concentrations, in contrast, were relatively the same in both types of oocytes. The ratio of sodium to potassium in large oocytes was markedly depressed from that seen in normal oocytes. Treatment of normal, immature (germinal vesicle stage) oocytes with EDTA produced: (1) loss of potassium, (2) an influx of sodium and (3) an elevated Na/K ratio. Similar alterations were not observed when large oocytes recovered from the ovary or the body cavity following ovulation were treated with EDTA. Progesterone pre‐treatment of normal and large oocytes recovered from the ovary inhibited the response of the normal but not large oocytes to EDTA. Normal immature and large oocytes recovered from the ovary extensively incorporated yolk protein precursor 3H‐vitellogenin. Following ovulation 3H‐vitellogenin incorporation was markedly depressed in normal oocytes whereas large oocytes continued to incorporate at a much higher rate per unit surface area and did not undergo ultrastructural changes (retraction of microvilli) which are associated with suppression of vitellogenin incorporation. Ultrastructural analysis revealed that large oocytes in contrast to normal oocytes were devoid of cortical granules, contained few yolk platelets and numerous lipid droplets. In addition, the cytoplasm of large oocytes contained numerous microsporidia at various stages of differentiation. The results indicate that large oocytes are viable cells but undergo drastic alterations in their development, composition and function, in association with the parasitic infection. The significance of these interrelated changes are discussed in relation to the mechanisms of infection and those of gamete differentiation.
Timing of sperm transport, sperm penetration and cleavage in the rat
Authors: Shalgi R. , Kraicer P. F. 
Published: June 2005

AbstractTimes of sperm entry into the oviduct from the uterus, into the ampulla from the isthmus; of sperm penetration into oocytes, and of cleavage, were determined using three mating regions. Time intervals and their errors of estimation were calculated. Spermatozoa were first found in the isthmus of the oviduct no earlier than 15 minutes after coitus, but required four hours to ascend the oviduct to the ampulla. The rate of sperm arrival was equal to the rate of sperm penetration, i.e., about 3 sperms/hour. Time of cleavage in vivo was 20.6 hours after sperm penetration in ad libitum mated animals. In culture, oocytes cleaved at exactly the same time as in vivo. Delaying sperm arrival to the site of fertilization (by delaying mating) shortened the time interval between median time of sperm penetration and median time of cleavage. It was concluded that the time of cleavage of the oocyte reflects primarily the time of sperm penetration, but is also influenced by the postovulatory age of the oocyte.
Renal regulation of acid‐base balance in a freshwater fish
Authors: Wood Chris M. , Caldwell Forrest H. 
Published: June 2005

AbstractIntra‐arterial injection of a fixed acid load caused only a short‐lived (< 2h) disturbance of blood pH but a long lived (2–3 days) elevation of urinary acid excretion in freshwater trout (Salmo gairdneri). The renal response comprised an immediate increase in acid output in the form of titratable acidity minus bicarbonate, and a slower rise in acid output in the form of ammonia. The total elevation in urinary acid efflux over 72h was such that no other mechanism besides renal function is needed to explain the ultimate compensation of this experimental acid‐base disturbance.
Site‐specific sperm agglutination and the timed release of a sperm chemo‐attractant by the egg of the leptomedusan, Orthopyxis caliculata
Authors: Miller Richard L. 
Published: June 2005

AbstractIn Orthopyxis sperm entry apparently occurs at the site of emission of the polar bodies. If sperm are present from the time of spawning of the egg, they agglutinate head to head shortly after emission of the second polar body but only at a point on the egg surface under the second polar body. Since sperm agglutination does not occur elsewhere on the egg, it appears that this part of the surface of the egg of Orthopyxis and probably other hydromedusae is a special membrane patch which causes sperm to bind reversibly both to it, and to each other. The patch develops at a specific time during egg maturation and ceases function at or just after fertilization. Concomitant with the appearance of the patch is the production of a species‐specific sperm attractant by the egg. These results imply that the egg has strict control not only of the site and timing of sperm penetration but also of the time during which sperm are attracted to the egg.
Testosterone and 5α‐dihydrotestosterone inhibit both growth and spermatogenesis in the remaining testis in partially castrated adult newts, Notophthalmus viridescens
Authors: Scadding Steven R. 
Published: June 2005

AbstractThe testis of the newt, Notophthalmus viridescens, undergoes hypertrophy following partial castration. Injections of either testosterone or 5α‐dihydrotestosterone are equally effective in inhibiting the increase in testis weight which follows partial castration. In addition, both of these androgens inhibit spermatogenesis, i.e., spermatogonia appear to be inhibited resulting in early cessation of spermatogenesis and a precocious division of the testis into separate spermatogonia and sperm compartments.
Effects of continual mechanical agitation prior to cleavage in echinoderm eggs
Authors: Rappaport R. 
Published: June 2005

AbstractThe force necessary to accomplish animal cell division is exerted by a ring of specialized cytoplasm which is rapidly established at the equatorial surface by the mitotic apparatus. Although the structure of the cleavage mechanism is not demonstrable before it is functional, the geometrical relation between the mitotic apparatus and the equatorial surface is established early in the mitotic cycle and remains unchanged. In order to learn more about the process by which the mitotic apparatus establishes the division mechanism, regions of cleaving echinoderm eggs (Echinarachnius parma, Lytechinus pictus) were continually agitated or stretched while establishment took place. Normal cleavage occurred despite stroking and vibration of the equatorial surface at different frequencies. Cells continually stretched at right angles to the future cleavage plane produced temporally and morphologically normal furrows. Subsurface cytoplasm was agitated by moving the mitotic apparatus back and forth parallel to its axis and by a vibrating needle inserted between the mitotic apparatus and the equatorial margin of flattened cells. Neither of these operations blocked cleavage. Cells held and shaped by the nozzle of a pipette were pierced by a needle inserted through the polar surface and into the zone between the mitotic apparatus and the equatorial surface. The needle was then swept around the entire mitotic apparatus. Furrows developed in these cells; they appeared later than in controls and did not appear completely normal. Furrow establishment does not seem to depend upon a precise, long‐standing, stable arrangement of sub‐surface cytoplasmic components.
The effect of oxygen on the development of preimplantation mouse embryos in vitro
Authors: Quinn P. , Harlow Gaye M. 
Published: June 2005

AbstractThe optimal oxygen tension for development of preimplantation mouse embryos to the blastocyst stage in vitro was found to be between 2.5% and 5%. One‐ and two‐cell embryos had a more sharply defined range of oxygen tension capable of supporting development than 8‐cell and morula stages. At all stages of development, more embryos developed to the blastocyst stage under 5% O2 compared to the numbers of developing under higher oxygen tensions (20% and 40% O2). The blastocysts developing under 20% O2 had fewer blastomeres than those which developed under 5% O2. As the time required for development to the blastocyst stage in vitro increased, there were fewer blastomeres present at the blastocyst stage.These results indicate that the cleaving mouse embryo has an optimal oxygen requirement in vitro of about 5%. At higher oxygen tensions, fewer embryos develop to the blastocyst stage and in those which do develop, there are fewer cell divisions. If a gradient of oxygen tension exists across the blastomeres from the outside of the embryo to its centre, the blastomeres might be using this gradient to obtain information about their location within the embryo and respond accordingly. Thus blastomeres on the outside at a higher oxygen tension would divide at a slower rate and form trophectoderm whereas those on the inside at a lower oxygen tension would divide more rapidly and contribute to the inner cell mass.
Contraction in a muscle with negligible sarcoplasmic reticulum: The longitudinal retractor of the sea cucumber Isostichopus badionotus (Selenka), holothuria aspidochirota
Authors: Hill Robert B. , Sanger Joseph W. , Yantorno Robert E. , Deutsch Carol 
Published: June 2005

AbstractThe longitudinal retractor muscles of the body wall of the sea cucumber Isostichopus badionotus have small cells joined in small bundles by extensive areas of tight surface contact between the cells and on projections at the center of the bundles. The cells have only a few small mitochondria and negligible sarcoplasmic reticulum. It might be expected that such cells would be poor in intracellular storage sites for calcium for excitation‐contraction coupling. However, we have found that it requires up to ten hours incubation of the isolated muscles in calcium‐free solutions of chelating agents to abolish contractility in the calcium‐free solutions. After that, contraction is directly calcium dependent. Contractility was assessed by measuring either force or shortening during potassium depolarization across a sucrose gap. Caffeine induces contraction even in calcium‐free solutions. Thus the physiological evidence indicates that there are internal storage sites for calcium, even though there is scarcely any sarcoplasmic reticulum. On morphological grounds we suggest that there are also superficial sarcolemmic storage sites for calcium. This is suggested by the great increase in sarcolemmic area provided by extraordinary extensions of each cell into the lumen of the bundle.
Temporal aspects of starfish oocyte maturation and 1‐methyladenine metabolism in vitro
Authors: Glad R. W. , Schuetz A. W. 
Published: June 2005

AbstractThe temporal relation between hormone uptake, metabolism, and reinitiation of meiosis was investigated following in vitro incubation of immature starfish oocytes with the maturation inducing hormone 1‐methyladenine (1‐MA) and/or 3H‐1‐methyladenine (3H‐1‐MA).Oocyte incorporation of the radioactive marker occurred in a dose dependent fashion and in excess of that required for maturation. Uptake and metabolism of the hormone by oocytes took place at subthreshold doses of 1‐MA as well as maturation inducing doses. Oocytes also concentrated radioactivity following incubation with physiologic doses of 3H‐1‐MA. Chromatographic analysis of oocyte radioactivity indicated that greater than 90% of the hormone incorporated by the oocytes existed as a single metabolite and this percentage remained constant over a 6‐hour time period. Metabolite was also isolated from the culture media and the quantity in the media increased with increased duration of incubation. After six hours, the metabolite accounted for 28% of the total culture media radioactivity. Determination of the rate of release of 3H‐marker from preloaded oocytes indicated that release was insufficient to account for the levels of metabolite found in the culture media. Such results suggest that at least a portion of 1‐MA metabolism occurred to the exterior of the cell membrane. Oocyte uptake as well as release of incorporated radioactivity were both suppressed by incubation at 0°C. However, at 0°C the proportion of oocyte incorporated radioactivity isolated as metabolite was similar to that following incubation at 22°C. The high and constant level of metabolism of incorporated hormone by oocytes, as well as the continued metabolism despite suppression of uptake suggests that a close association exists, possibly at the level of the oocyte cell membrane, between 1‐MA uptake and formation of metabolite in the starfish oocyte.
Continuance of circannual reproductive refractoriness in pinealectomized parthenogenetic whiptails (Cnemidophorus uniparens)
Authors: Cuellar Hector S. 
Published: June 2005

AbstractTwelve control and thirteen pinealectomized lizards (Cnemidophorus uniparens) were exposed to a temperature gradient of 27°C to 42°C and a 10L:14D photothermal regime for nearly one year starting during the latter part (late October‐early November) of their reproductive refractory period. This lizard is refractory to photothermal stimulation in captivity from early July to mid‐December. Two pinealectomized animals became reproductive by mid‐November but the remaining in both groups became reproductive as usual starting in December. These results conflict with those reported for another lizard in which pinealectomy in the winter resulted in significant ovarian activity. The data presented here demonstrate that the pineal organ does not play a role in the endogenous circannual cycle of this lizard but may be involved in thermoregulation as reported for other lizards.
Blood viscosity in annelids
Authors: Snyder Gregory K. 
Published: June 2005

AbstractThe intrinsic viscosity of hemoglobin from the marine annelid Arenicola marina is less than 25% of the value predicted for a linear polymer of comparable molecular weight. The relatively low Viscosity, which appears to be related to the subunit arrangement in annelid hemoglobins, provides a much higher than predicted blood oxygen transport capacity.
Facial development in normal and mutant chick embryos. I. Scanning electron microscopy of primary palate formation
Authors: Yee G. Wendel , Abbott Ursula K. 
Published: June 2005

AbstractEarly facial development in normal chick embryos was studied by scanning electron microscopy, and compared to the abnormal facial development of a mutant in which primary palate formation does not occur, thus resulting in bilateral cleft lip. In both normal and “cleft primary palate” mutant embryos, subsequent to the appearance of the nasal placodes, the surrounding tissues elevate to give rise to the presumptive facial primordia. As the facial primordia grow forward, they gradually assume the configuration of a square which is most pronounced at five days development.In normal embryos, the square configuration is then lost as the facial primordia become aligned in preparation for primary palate formation. The primary palate is formed at six days development by fusion of the “free‐ended” medial nasal processes with the combined lateral nasal and maxillary processes across the nasal grooves. Just prior to fusion, long, slender filaments extend from the apposing surfaces of the facial primordia in the regions of prefusion contact. It is speculated that these “prefusion filaments” may function in alignment or adhesion of the facial primordia.In “cleft primary palate” embryos, facial morphogenesis appears to arrest at five days development, so that the square configuration persists. The medial nasal processes never contact the lateral nasal and maxillary processes, but instead remain separated from them by wide nasal grooves. Furthermore, facial primordia of mutant embryos do not exhibit the “prefusion filaments” characteristic of normal embryos.
NA++K+‐ATPase in the osmoregulating clam Rangia cuneata
Authors: Saintsing David G. , Towle David W. 
Published: June 2005

AbstractOf six tissues sampled from the osmoregulating clam Rangia cuneata, mantle contained the highest concentration of Na++K+‐ATPase activity and ouabain binding sites. Acclimation to low salinities was accompanied by adaptive increases in Na++K+‐ATPase activity in mantle but not in gill. Since the number of ouabain binding sites did not show parallel increases, the mechanism of acclimation to reduced salinity in Rangia appears to involve activation of pre‐existing pump sites in the mantle epithelium.
Effect of acclimation temperature on plasma levels of glucose and lactate in rainbow trout, Salmo gairdneri
Authors: Connors Thomas J. , Schneider Mark J. , Genoway Robert G. , Barraclough Stephen A. 
Published: June 2005

AbstractBaseline plasma glucose and lactate levels were determined in unstressed rainbow trout (Salmo gairdneri) acclimated to 8°, 12°, and 16°C. The 8°C acclimated fish had the highest plasma glucose level (75.7 mg/dl), which is significantly greater than the 16°C acclimated fish (59.7 mg/dl) but not the 12°C fish (66.7 mg/dl). The plasma glucose levels of the 12°C and 16°C acclimated fish were not statistically different. The plasma lactate levels of 8°C fish (5.3 gm/dl), 12°C fish (4.2 mg/dl) and 16°C fish (5.3 mg/dl) were not significantly different. There was significant positive correlation between weight and length and significant negative correlation between plasma glucose and both weight and length. No other significant correlations between parameters were detected.
Satellite cells are mitotically quiescent in mature mouse muscle: An EM and radioautographic study
Authors: Schultz Edward , Gibson Marcia C. , Champion Thomas 
Published: June 2005

AbstractNormal adult mouse tibialis anterior muscles were perfused continuously with 3H‐thymidine for nine days. Quantitation of the satellite cell population in these muscles reveals that not only is the frequency of satellite cell nuclei low, but that those present are mitotically quiescent.