摘要:

AbstractThe following experiment was designed to test the role of sensory input in the motility of the chick embryo: Complete deafferentation of the leg level was accomplished in 2‐day embryos by extirpation of the dorsal half of the lumbar spinal cord including the precursor cells of spinal ganglia; and simultaneous extirpation of the entire spinal cord in the thoracic level to exclude sensory input from more rostral levels. In control embryos, only the thoracic gap was made. The embryos were reared to eight and one‐half, 11, 13, 15 and 17 days, respectively, and manual recordings were made of the leg motility before the embryos were sacrificed. It had been reported by us that the motility of normal chick embryos is periodic, activity phases alternating with inactivity phases. Both the overall activity, i.e., percent of activity during a standard 15‐minute observation period, and the durations of activity and inactivity phases were found to be the same in experimental embryos and in control embryos with thoracic gaps, at least up to and including 15‐day embryos. Histological checks showed the complete absence of lumbar spinal ganglia in the majority of embryos and, the presence of a few small thoracic ganglia in some cases. All embryos with lumbar ganglia were discarded. The motor roots formed a normal plexus, and the pure motor nerves emerging from it showed a normal peripheral distribution and muscle innervation. It is concluded that the leg motility results from autonomous discharges of the lateral motor or internuncial neurons, and that sensory input is not necessary for the triggering, the maintenance or the periodicity of the leg motility. A sharp decline of motility was observed in 17‐day embryos. A study of the histological condition of the residual spinal cord showed a numerical depletion and partial degeneration of the lateral motor column. This deterioration is considered to be responsible for the functional impairments.The implication of these results for the widespread notion that “self‐stimulation” and similar “experiences” during embryonic development play an important role in the molding of be

ISSN:0022-104X    

DOI:10.1002/jez.1401620202

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

年代:1966

数据来源: WILEY

摘要:

AbstractHuman blood leucocytes from certain individuals culturedalone— as “controls” for experiments designed to demonstrate the mutual reactivity of mixed cultures of leucocytes from different donors — revealed an intense proliferative response by the fifth day as measured by the incorporation of radioactive thymidine. Furthermore, thymidine incorporation into control leucocyte cultures from most donors was markedly elevated by the seventh day of culture. Because these high background levels tended to obscure the mutual reactivity of mixed leucocyte cultures, experiments were designed to elucidate the nature of and to circumvent these difficulties. By supplementing the growth media with human plasma, rather than calf serum, the background activity of the control cultures could be maintained at low levels without compromising the mutual reactivity of lymphocytes in the nixed cultures. One other source of variability which proved simple to control was the relative number of “contaminating” non‐lymphoid cells in the cultures. This factor was important since, in the preparation of the leucocyte suspensions with erythrocyte sedimentation procedures, the number of contaminating granulocyte cell types can be expected to vary over a wide range.Phytohemagglutinin (PHA) was used as a mitogen in experiments designed to define further some of the parameters of the lymphocyte responsein vitro.When a standard number of lymphocytes — either as a “purified” suspension or as one containing significant numbers of contaminating granulocytes — was cultured with various concentrations ofPHA, a dose‐dependent response was observed. Partially purified lymphocyte suspensions were only one‐half to one‐third as active as non‐purified leucocyte suspensions containing the same number of lymphocytes. This could not be attributed to a deleterious effect ofPHAon purified cultures with a lower cell density since (1) the peak response of both cultures occurred with thesameconcentration ofPHA, and (2) the maximal reactivity toPHAcould be restored by incre

ISSN:0022-104X    

DOI:10.1002/jez.1401620203

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

年代:1966

数据来源: WILEY

摘要:

AbstractThe histochemical localizations of acetylcholinesterase, monoamine oxidase, epinephrine, norepinephrine, 5‐hydroxytryptamine, and neurosecretory substance were investigated inSycon.All reactions that were most intense and sensitive to inhibitors were localized in spindle‐shaped bipolar cells and multipolar cells situated in the mesenchyme. Some spindle‐shaped cells formed a ring around the osculum and others contained branching and interconnecting processes. Multipolar cells were situated singly and possessed up to ten short processes. Activity was most commonly localized to small granules, vesicles, or large droplets within the cells and their processes. These results demonstrate the presence of cells specialized for the secretion of neurohumors and neurosecretory substance in sp

ISSN:0022-104X    

DOI:10.1002/jez.1401620204

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

年代:1966

数据来源: WILEY

摘要:

AbstractComparative studies were made of the exocrine pancreas in normal, thyroidectomized, and thyroxine treatedRana pipienstadpoles during various stages of development. The weight of the pancreas as milligram per cent body weight (mg% B.W.) is greatly reduced during both artificially induced and natural metamorphosis. During natural metamorphosis the reduction in mg% B.W. of the pancreas begins in the early larval stages and continues in a consistently decreasing pattern through the final stages with the maximum reduction (69%) occurring by the mid‐larval stages (XVI‐XX).In thyroxine treated tadpoles, reduction in mg% B.W. of the pancreas is directly proportional to hormone concentration and the relative weight of the gland is significantly less than that observed in any of the controls of equivalent limb stages even though the absolute weight of the gland has increased over that of the earliest stages (I–V). The pancreas of the thyroidectomized tadpoles showed no significant difference in mg% B. W. when compared to that of a normal control of equivalent limb stage range. Histological investigation of the pancreas revealed no evidence of widespread cellular necrosis of the exocrine elements. Some acinus disorganization, typified by large spaces in the connective tissues and a syncytial nature of the acinar cell cytoplasm, can be seen in the later stages. A discussion of the possible role of thyroid hormone in the normal development of the pancreas is presented. It is concluded that reduction in the mg% B.W. of the pancreas is a naturally occurring phenomenon during metamorphosis resulting from intestinal evacuation and water loss. The water loss may be influenced and regulated indirectly by thyroxine through an effect on cellular and subcellular membrane permeab

ISSN:0022-104X    

DOI:10.1002/jez.1401620205

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

年代:1966

数据来源: WILEY

摘要:

AbstractEmbryos ofAmblystoma punctatumwere x‐irradiated with 500 r to 2,000 r at stages 28–30. A rectangle of ectoderm including postauditory placodal material was transplanted orthotopically from the right side of irradiated embryos to nonirradiated hosts of the same age. Controls consisted of the same operation between non‐irradiated embryos. Animals were studied at stage 46 to determine the effects of irradiation upon development of lateral‐line migratory primordia, nerves and ganglion.The dorsal lateral‐line was most affected by irradiation, averaging approximately 90% less organs and 85% less nerve fibers than normal. Midbody lateral‐line averaged approximately 65% less organs and 55% less nerve fibers. There was no reduction in number of ventral lateral‐line organs and scarcely any in number of nerve fibers. Number of lateralis ganglion cells averaged approximately 62% less than normal. Control animals developed normal numbers of organs and nerve fibers in all three lateral‐lines and showed no appreciable reduction of ganglion cells on the operated side.X‐irradiation affects the migration of lateral‐line primordia as well as the proliferation or maturation of Xth lateralis nerve cells. Normality of the ventral lateral‐line in these experiments requires

ISSN:0022-104X    

DOI:10.1002/jez.1401620206

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

年代:1966

数据来源: WILEY

摘要:

AbstractA detailed analysis of the puffing patterns of Malphigian tubules, stomach and salivary glands ofDrosophila hydeirevealed that from a total of 110 easily recognizable puffs 76 (69%) are present in all tissues at one time or another during mid and late third instar. A small number of puffs showed tissue specific activity. Three such puffs were restricted to the Malphigian tubules, four to the stomach and seven to the salivary glands. A number of puffs was found to be absent in only one of the investigated tissues during the whole of the period. A comparison of the puffs specific for a definite developmental stage revealed that from the 22 puffs in the salivary glands which were specific for the period of puparium formation, only six showed an identical reaction in all tissues. In the late third instar stage three puffs were observed to become active earlier in the stomach than in the salivary glands, whereas no activity of these puffs was found in the Malphigian tubules. A possible relation of these puffs to the process of histolysis is discussed.A comparison of the puffing patterns of Malphigian tubules in larvae and in adults showed that 12 puffs which were observed in the larvae were absent in the adults. No specific puffs occurred in the adult Malphigian tubules.

ISSN:0022-104X    

DOI:10.1002/jez.1401620207

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

年代:1966

数据来源: WILEY

摘要:

AbstractA total of five molecular forms of hemoglobin appear during the development of the chick embryo. In the seven day embryo, the earliest stage studied, four of these forms are present. Hb I, preponderant in the early embryo, decreases to become a minor component at hatching; Hb II, a minor component in the early embryo, increases to become the major component at hatching; Hb III is present throughout as a minor component. Hb IV is first detectable in the nine day embryo and remains a minor component. Hb E is present as a minor component in the seven day embryo and is last found in the eleven day embryo. After hatching there is no further change in the hemoglobin pattern.In ovooxygen deficiency and chromate retard the progressive shift from Hb I to Hb II.In vitrooxygen deficiency and chromate accelerate heme synthesis and preferentially the synthesis of Hb I.Cobaltin vivoresults in a decrease in Hb I and a corresponding increase in Hb III and Hb IV. Thein vivoincorporation of Fe59indicates that the effect of cobalt is to enhance the rate of degradation of Hb I.The progressive shift from Hb I to Hb II which occurs in normal embryogenesis is discussed in terms of the control of hemoglobin synthesis at the translational level.

ISSN:0022-104X    

DOI:10.1002/jez.1401620208

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

年代:1966

数据来源: WILEY

摘要:

AbstractSpecies representing three rotifer genera have been investigated with special emphasis on elucidating the detailed fine structure relationships of integumental derivatives. The classical concept of cuticulization in these animals must be modified to incorporate the finding that a genuine extracellular cuticle is lacking in a species thought to be very heavily cuticulized (loricate) namely,Keratella cochlearis.A consistent intracellular structural entity located just beneath the hypodermal plasma membrane is thought to represent the bulk of the reinforcing or exoskeletal material observed in all rotifers thus far examined. InPhilodina, this “dense layer” is shown to be an insertion point for fiber tracts associated with muscle‐hypodermis desmosomes. The desmosomes are of interest in themselves since they are not of the septate type observed previously in rotifers and invertebrates in general, but are of the “standard” variety more commonly seen in highe

ISSN:0022-104X    

DOI:10.1002/jez.1401620209

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

年代:1966

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1401620201

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

年代:1966

数据来源: WILEY