摘要:

AbstractThe quadratojugal‐quadrate articulation from 9–12 day chick embryos was cultivatedin vitroand subjected to artificial mechanical stimulation by moving the quadratojugal against the quadrate. Under the influence of this artificial application of intermittent pressure and tension it was found that the germinal cells of the membrane bone were switched from osteogenesis to adventitious chondrogenesis. The quadratojugal‐jugal articulation was treated in a similar manner but no formation of cartilage was seen. Quadratojugal‐quadrate articulations were also cultivated between “rib‐cultures” under constant pressure and it was found that no switch to cartilage formation occurred. It was postulated that the adventitous cartilage which develops on the membrane bones of the embryonic chick arises in response to intermittent pressure and tension accompaine

ISSN:0022-104X    

DOI:10.1002/jez.1401680302

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

年代:1968

数据来源: WILEY

摘要:

AbstractVocalizations can be elicited from some duck embryos five and one‐half days before hatching and from some chick embryos three days before hatching. All duck embryos can vocalize three and one‐quarter days before hatching (at 88% of incubation period) and all chick embryos are able to vocalize one day before hatching (95% of the incubation perod). Thus, the vocal apparatus of the duck embryo achieves a functional stage of development sooner that that of the chick embryo, indicating that the syringeal structures of the duck embryo begin development sooner or develop at a faster rate than those of the chick embryo. According to audiospectrographic analysis, both species are capable of uttering at least three different kinds of vocalizations prior to hatching, and these three calls are similar to the ones emitted most frequently after hatching (“distress,” “contentment,” and brooding‐lke calls). These vocalizations can be objectively defined by reference to the contexts in which they are emitted and the physical structure of the call notes. It was verifiedin situthat the constriction and vibration of the tympaniform membranes during exhalation is the basic or primary source of sound production in birds. The clavicular sac is not essential to sound production, and the syrinx, trachea, and syringeal muscles are important only for modulating and/or resonating the sounds produced by the tympaniform membranes. Based on this knowledge, a technique was devised to de‐vocalize duck embryos 3 days before hatching. The technique involves immobilizing the tympaniform membranes by applying a nontoxic substance (“Collodion”) to them. Collodion forms a glue‐like sheath over the membranes, and when the tympaniform membranes are thus rigidified, the embryo can not vocalize. Eighty‐five percent of the embryos treated were completely mute after hatching. The long‐term effectiveness of the de‐vocalization procedure is not reliably known. It was possible to keep only one bird for observation beyond the first four days after hatching and she was still

ISSN:0022-104X    

DOI:10.1002/jez.1401680303

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

年代:1968

数据来源: WILEY

摘要:

AbstractThe prosobranch limpetAcmaea scutumis found in both marine and estuarine environments. A number of parameters affect the water balance of this limpet.A. scutumhas little control of total water content. Total water changes with season, size of animal, and salinity. Limpets from a marine environment, when immersed in experimental salinities for up to one week, are unable to regulate total body water. Estuarine limpets however, are able to regulate total body water in experimental salinities between 24 and 48 hours immersion. The ability to regulate water content between 24 and 48 hours is probably not important in the estuarine environment. Studies on the effect of field salinity on the water content of estuarine animals show that changes in field salinity of about 15% sea water resulted in significant changes in total body water.Water content of muscle tissue and muscle cells of marineA. scutum, like body water values, conform when external salinity is changed. Estimates of intracellular water per unit of muscle tissue (using inulin space as extracellular space) changed with external salinity from 79.3% at 50% sea water to 57.7% at 125% sea water.

ISSN:0022-104X    

DOI:10.1002/jez.1401680304

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

年代:1968

数据来源: WILEY

摘要:

AbstractIn the three amphibian speciesBombina variegata, Rana temporariaandTriturus alpestristhere is a two‐ to threefold increase in the total content of saline‐soluble proteins during development (prior to feeding). Analyses by polyacrylamide gel electrophoresis revealed the appearance of one or two new protein fractions at gastrulation. Protein bands of transitional occurrence were also observed at various developmental stages. In general, during early embryogenesis protein components with relatively low migrating rates in the anodal direction predominate, whereas in the late larvae fractions of higher mobilities are more abundant.The isozymic patterns of four dehydrogenases in both embryonic and adult tissues of the three amphibians have been analysed. Three molecular forms of lactate dehydrogenase (LDH) are present inBombinaandTriturus, and two inRana. TriturusandRanahave only a single malate dehydrogenase (MDH), whereasBombinahas two with, however, a clear difference in the mobility of the minor band between embryonic and adult stages. The total number of molecular forms of glucose‐6‐phosphate dehydrogenase (GDH) varies from four inBombinato two inRanaandTriturus.There are probably four to five isozymes of alcohol dehydrogenase (ADH) of very low activity.Morphogenetic changes of the isozymic patterns include the appearance of one MDH inBombinaand the gradual increases in activities of LDH, GDH and MDH inRanaat gastrulation. After hatching further appearance of ADH isozymes occurs. The new synthesis of one GDH in the lateBombinalarvae seems largely associated with the differentiation of heart and fat body. The formation of one MDH in this amphibian is probably delayed until after metamorphosis. A shift in the relative synthesis of isozymes duringBombinadevelopment is indicated by the temporary loss of one LDH band at tail‐bud formation and after

ISSN:0022-104X    

DOI:10.1002/jez.1401680305

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

年代:1968

数据来源: WILEY

摘要:

AbstractA cycloheximide‐resistant, yellow variant of the true slime mold,Didymium nigripes, has been isolated. It exhibits aging as exemplified by a loss of ability to fruit, fuse with other plasmodia, and grow. It is often rejuvenated after fruiting or being present in a heteroplasmodium with the wild type. The behavior of subclones was very variable, but the behavior of populations of clones was predictabl

ISSN:0022-104X    

DOI:10.1002/jez.1401680306

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

年代:1968

数据来源: WILEY

摘要:

AbstractThe anatomy and innervation of the swimmeret muscles of the lobsterHomarus americanuswere studied using histological and intracellular recording techniques. Each swimmeret is controlled by 12 muscles, each of which comprises from one to five anatomically‐distinguishable bundles of muscle fibers. The bundles which make up each muscle are usually merged along part of their lengths. Sometimes, however, bundles which share efferent innervation and which are therefore part of a single functional muscle are separate along their entire lengths. Thus, the concept of a muscle as a discrete anatomical unit is of limited use in the swimmeret system.The pattern of neuromuscular activity underlying swimmeret beating was determined by recording the rhythmic movements of a swimmeret simultaneously with the electrical activity of its muscles. Each muscle is active for a fixed fraction of every movement cycle, during which it discharges several muscle potentials. The 12 muscles of each swimmeret are recruited in the same temporal sequence during each cycle of swimmeret beatin

ISSN:0022-104X    

DOI:10.1002/jez.1401680307

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

年代:1968

数据来源: WILEY

摘要:

AbstractProduction of chromosomal abnormalities by x‐raying Amphibian zygotes is not necessarily followed by blastular arrest. At an x‐ray dose that produces blastular arrest in 20% of the irradiated embryos, over 90% of the embryos were found to contain cells with gross chromosome aberrations.Different pregastrular stages are differentially sensitive towards x‐ray production of blastular a

ISSN:0022-104X    

DOI:10.1002/jez.1401680308

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

年代:1968

数据来源: WILEY

摘要:

AbstractUsing microsurgical techniques spinal “gaps” were made in the thoracic level of chick embryos at two days of incubation by removing small lengths of neural tissue. These same embryos were then examined in detail between 17 days and hatching for any behavioral modifications.The frequency and patterns of various movements anterior to the gap were found to be similar to control embryos. Leg movements were also found to be equal in number to those of the controls. Operated embryos, while being able to orient correctly in the egg and to pip the shell, were not able to hatch on their own. This was due to an inability of these embryos to coordinate movements of the legs with movements anterior to the spinal gap, and to the absence of vigorous stemming movements of the legs against the shell. This prohibited them from cracking and rotating around the sell and hence from hatching.Three of the spinal embryos which were artificially hatched (pulled out of shell) were not able to stand or walk after two days. However, the legs of these chicks did show “spontaneous” alternating kicking movements and were responsive to stim

ISSN:0022-104X    

DOI:10.1002/jez.1401680309

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

年代:1968

数据来源: WILEY

摘要:

AbstractThe right wing of chick embryos, stages 17–18, was extirpated with a view to study the effect of the absence of the right wing on prehatching motility and hatching behavior. Half of the embryos which survived, hatched normally. Detailed observations on these embryos showed that they followed the typical sequence of behaviorial events from day 17 until hatching. The types of behavior patterns were strikingly similar to embryos with both wings intact. A comparison of the qualitative aspects of prehatching behavior showed an increase of head movements in embryos without the right win

ISSN:0022-104X    

DOI:10.1002/jez.1401680310

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

年代:1968

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1401680301

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

年代:1968

数据来源: WILEY