摘要:

AbstractSpecimens ofTriturus cristatus carnifex(Laurenti) raised for about 3 weeks in a 3 gm/liter solution of sodium lactate present a slight alkalosis and a mean increase of about 35% in the red blood cell count in comparison to control animals raised in identically oxygenated water; analogous treatment with an equal molar concentration of sodium pyruvate produces only alkalosis. Since lactate alone determines an increase in the number of erythrocytes as does hypoxia, and hypoxia always induces an increase in plasma lactate levels, it can be deduced that erythropoietin (ESF) production is stimulated by an increase in plasma lactate and not directly by a lack of oxygen. The hypothesis that ESF in newts is produced by the “lactate‐sensitive cells” of the renal corpuscles, which hypertrophy after experimental anaemia or treatment with lactic acid salts, is indirectly conf

ISSN:0022-104X    

DOI:10.1002/jez.1402250102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractAdult female armadillos were injected with tritiated estradiol. The Harderian gland was removed and processed for autoradiography. Nuclear uptake and retention of the steroid were observed in the duct of the gland, the periductal mucous cells of the mucus‐secreting lobules, and the fibroblasts in the interstitial connective tissu

ISSN:0022-104X    

DOI:10.1002/jez.1402250103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe pathway of β‐alanine (BALA) oxidation was examined in the liver of the little skate,Raja erinacea.BALA oxidation in liver slices was reduced by inhibitors of transamination and mitochondrial electron transport. Experiments with liver homogenates indicated that BALA was oxidized by a two step process: (1) transamination of BALA to malonate semialdehyde (MSA) and (2) conversion of MSA to CO2and acetate. Increases in BALA oxidation during osmotic stress are probably mediated by changes in substrate concentration rather than alterations in enzyme leve

ISSN:0022-104X    

DOI:10.1002/jez.1402250104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractEach leg of a crayfish embodies two types of morphogenetic fields, a limb field and a sequence of segmental fields. These fields were manifest in grafting operations along the proximodistal axis of legs 3 and 4. The propodite was grafted into more proximal segments—carpopodite, meropodite, or basipodite—in one set of operations. In a second set the propodite was host for a graft from the propodite or carpopodite. After these operations intercalary regeneration yielded complete regenerates, which manifested the limb field, and incomplete regenerates, which showed the segmental field. Complete legs contained all structures present in a normal leg. After some operations complete legs also had supernumerary structures. Several types of incomplete legs regenerated—(1) legs with fusion of the host and graft segments; (2) legs with a joint girdling only part of the leg circumference; and (3) legs with one mosaic segment intercalated to replace two deleted segments. These results show that both limb and segmental fields control intercalation in the tested segments of crayfish legs, as in insect legs. We propose a “mode control hypothesis” to describe the way in which molt cycle phase and healing rate bias the type of field controlling regeneration. Our observations also provide clues about the operation of the fields to generate structures. Homologous parts of the segmental field do not necessarily generate analogous structures in different leg segments. Although intersegmental membrane often develops in conjunction with an apodeme (muscle tendon), in a mosaic joint intersegmental membrane can still develop in the absence of the corresponding apodeme. In a partial joint the length of the segments adjacent to the joint is subnormal, but greater than the length of the segments between which a joint is missing. The jointless region may limit the growth of the joint

ISSN:0022-104X    

DOI:10.1002/jez.1402250105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractSeven‐day‐old domestic ducklings were assigned to groups and fed freshwater and food ad libitum (control), 1% NaCl and food ad libitum (stressed), or freshwater and only as much food as the stressed group ate (starved). Tissues were sampled after 3 and 7 days. Other groups of ducklings were fed freshwater and food ad libitum for 9 days (control), 1% NaCl and food ad libitum for 7 days followed by freshwater for 2 days (de‐stressed), or freshwater and the same amount of food as the de‐stressed group for 7 days followed by food ad libitum for 2 days (de‐starved). Body weights were recorded and the femurs were analyzed. Univariate, multivariate, and allometric analyses clearly demonstrate that stressed and starved regimens influence femoral morphology differently. Stressing for 3 days reduced femoral ash and by 7 days had retarded femoral linear growth. Three days fo starvation produced no apparent effect on the femur, but starvation for 7 days reduced the amount of femoral ash/femoral lenght. Furthermore, major differences between stressed and starved ducks disappeared after de‐stressing for 2 days. Studies of bone growht and metabolism may benefit by using this

ISSN:0022-104X    

DOI:10.1002/jez.1402250106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe avian secondary palate exhibits the unique feature of a midline cleft. Cryostat sections indicated that although extensive contact between homologous shelves was present, chick palatal medial edge epithelium (MEE) failed to fuse. The failure of fusion and subsequent clefting of the avian palate were correlated with continued proliferation of the avian MEE, a failure of selective MEE cell death, and an absence of elevated levels of intracellular cAMP. Moreover, immunohistochemical staining for cAMP and microspectro‐photometric quantitation of staining intensity indicated that staining of chick MEE was significantly (p<.01) less than murine MEE at comparable gestational ages. These data indicate that differentiation of the avian secondary palate is fundamentally different than reported for the mammalian palate in that many developmental events known to be associated with normal mammalian palate formation (cessation of MEE proliferation, MEE cell death, elevated levels of MEE cAMP) fail to occur in the chick. The developing avian secondary palate, with its midline cleft, thus provides an interesting and useful model system with which to compare mammalian palate formation where the palate is normally fused in the midlin

ISSN:0022-104X    

DOI:10.1002/jez.1402250107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe asymmetric claws of Californian snapping shrimp (Alpheus californiensis) are comprised of a smaller pincer claw and a larger snapper claw. The present paper describes the morphology of the single closer muscle and the facilitation properties of an excitatory motor axon for both claws. In the snapper claw the closer muscle fibers are composed of uniformly long sarcomeres, measuring 10–15 μm in length. In the pincer the closer muscle fibers are of a smaller diameter and can be divided into two groups on the basis of sarcomere length. One group has short (2 and 3 μm) sarcomeres, while the other has intermediate (7 and 8 μm) sarcomeres. Microelectrode recordings from single closer muscle fibers showed that all fibers are supplied by the fast excitatory motor axon. The slow excitatory motor axon innervates only fibers on the dorsal and ventral surfaces of the closer muscle. Facilitation of excitatory junctional potentials (ejps), produced by stimulation of the fast axon with pairs of brief electrical shocks, revealed that at intervals above 100 ms no facilitation was recorded from either claw. At intervals below 100 ms, however, facilitation was recorded from pincer closer muscle fibers, but defacilitation or depression was recorded from the snapper. This was confirmed by making extracellular recordings of synaptic potentials from snapper closer muscle fi

ISSN:0022-104X    

DOI:10.1002/jez.1402250108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractAs a part of our continuing effort to understand the nature of the inhibition of thyroxine‐induced metamorphosis by prolactin in the tiger salamander, we examined the effects of delaying the initiation of prolactin treatment for progressively longer time intervals following the injection of a metamorphosing dose of thyroxine. Prolactin continued to inhibit gill resorption when given either 2 or 4 days following thyroxine, but the magnitude of the inhibition appeared to diminish. Delay of prolactin treatment until day 6 abolished the inhibition. In contrast, tail fin regression appeared to be inhibited in an undiminished fashion by prolactin given 2, 4, or 6 days following thyroxine. Body weight loss was inhibited in a similar manner. In a second experiment, actinomycin D, a transcription inhibitor, was observed to inhibit metamorphic changes. A delay of 5 days in the administration of this drug relative to thyroxine treatment produced a significant reduction in its inhibition of gill resorption, tail fin regression, and body weight loss. Surprisingly, late (day 5 following thyroxine) treatments with prolactin still produced a significant inhibition of fin regression and weight loss even when the inhibitory dose of actinomycin D was given on day 5 along with the prolactin. These results are discussed with respect to their implications concerning our understanding of the mechanism of prolactin action during amphibian metamorphosi

ISSN:0022-104X    

DOI:10.1002/jez.1402250109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractLeft caudal neural crest was ablated by diathermy in 2‐day‐old chick embryos, to injure the region of sensory sciatic innervation before the appearance of the hind‐limb bud. Embryos were fixed immediately, 24 hr and 14 days later, for examination of the effects of the ablation upon neural crest, neural tube, somitic mesoderm, and subsequent limb development. All embryos examined immediately and at 24 hr after ablation showed damage to the left neural crest, but the injury extended deeper into neural fold or tube, across the midline, and into somitic mesoderm. Of 17 chicks which survived to 16 days, 7 had gross deformity of the left leg and 10 had morphologically normal legs. Deformed chicks had a significant reduction in the mass of dorsal root ganglia on the operated side but no reduction in the area of the spinal cord. Operated chicks without limb deformities showed reduction of spinal cord but not of dorsal root ganglia. This suggests that limb morphogenesis may be quantitatively related to neural crest but not to neural tube. This possibility is considered in the light of previous publications. However, the experimental limitation of the diathermy method leaves the final conclusion open to interesting speculation and to future examination by improved experimental d

ISSN:0022-104X    

DOI:10.1002/jez.1402250110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractChimeric hydra were constructed from ectoderm of one strain and endoderm of a morphologically different strain. Body size and budding rate were assayed in three pairs of ectoderm/endoderm chimeras, which were chosen on the basis of their differences in size and budding rates. Reciprocal chimeras of one parental pair were the same size as their endodermal parent, while chimeras of another pair were closer to the ectodermal parents in size. Chimeras of the third pair were similar to one another in size, and intermediate in size between the parental strains. The budding rates of the three reciprocal pairs were similar to their ectodermal parents. This suggests that ectoderm exerts more influence than endoderm on budding rate, while both ectoderm and endoderm are capable of influencing the size of a hydra. The morphology of these three pairs of reciprocal chimeras and of a fourth pair of chimeras constructed from normalH. attenuataand a mutant strain which produces multiple basal discs were compared to the parental morphologies. Both ectoderm and endoderm contribute to the morphology of the chimeric strains.

ISSN:0022-104X    

DOI:10.1002/jez.1402250111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY