摘要:

AbstractAzure B staining of Cecropia moth ovarian follicles indicated that the pattern of RNA concentrations characteristic of vitellogenic oocytes is disrupted by a gross redistribution and dispersion, beginning with the final discharge of the cytoplasm of the nurse cells into the oocyte. The cytoplasmic redistribution is largely complete two days later when chorion formation begins, the germinal vesicle breaks down, and the first meiotic spindle forms.At this stage the follicle contains 30 μg of RNA, of which 27 μg are in the follicle cells and only 3 μg in the oocyte itself. The proportionately large amount of follicle cell RNA apparently reflects the synthetic functions of these cells in the formation of yolk and the secretion of chorion. Of the 3 μg in the oocyte, only 1 μg is incorporated into the early embryo while the remainder is found in the yolk cells and serosa.Autoradiography of follicles labeled with H3‐uridine eitherin vivoor by a “pulsechase” procedurein vitroindicated that, as in other polytrophic insect ovaries, the nurse cell nuclei are the most conspicuous source of oocyte RNA. The germinal vesicle incorporated labeled uridine in previtellogenic follicles. In vitellogenic and later stages neither a germinal vesicle nor a follicle cell contribution to oocyte RNA was detected by the proce

ISSN:0022-104X    

DOI:10.1002/jez.1401700102

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

年代:1969

数据来源: WILEY

摘要:

AbstractSpecimens of the ghost crab,O. ceratophthalma, ran at 1.825 ± 0.09 m/second on the sandy shore of the Flinders Islands and 2.33 ± 0.14 m/second on the deck of the R/V Alpha Helix. Specimens ofPachygrapus transversusran at 0.92 ± 0.06 m/second on the ship's deck. Sex did not affect speed.O. ceratophthalmais anatomically and functionally specilized for running. The gait ofO. ceratophthalmawas recorded cinematographically and could be described by the fastest variants of the model devised by Wilson ('66) for insect walki

ISSN:0022-104X    

DOI:10.1002/jez.1401700103

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

年代:1969

数据来源: WILEY

摘要:

AbstractNewts which were fed daily for two weeks prior to hypophysectomy survived significantly longer and regenerated limbs better than newts fasted for two weeks prior to hypophysectomy. Since limbs were amputated five days after hypophysectomy, regeneration was initiated in the complete absence of pituitary hormones.Newts which were hypophysectomized 14 days after limb amputation were found to possess blastemas significantly smaller at eight and also at 16 days after the operation than the blastemas of sham‐operated newts. Thus, hypophysectomy, performed after limb regeneration had progressed through the wound healing and dedifferentiation phases, resulted in a significant retardation in the growth of the blastema.To determine which hormones are essential to normal limb regeneration and survival, newts were hypophysectomized and treated with various combinations of hormones, or grafted with pituitaries from newts or from axolotls (Ambystoma mexicanum). A prolactin‐thyroxine combination, growth hormone, and ectopic pituitary grafts from newts or axolotls, significantly prolonged the life of hypophysectomized newts. These newts also regenerated limbs in a normal fashion. Thyroxine alone, prolactin alone, thyroxine + ACTH, ACTH, or saline were not effective in restoring the health of hypophysectomized newts and were not effective in restoring normal limb regeneration abil

ISSN:0022-104X    

DOI:10.1002/jez.1401700104

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

年代:1969

数据来源: WILEY

摘要:

AbstractRabbit embryos were subjected to heat‐stress during the first cleavage division. Those embryos to be heat‐stressedin vitrowere recovered at 19 hours after mating and incubated at either 38° or 40°C for six hours, then returned to the original doe. Others were heat‐stressedin vivoby subjecting the doe to a temperature of either 21° or 32°C for 28 hours beginning four hours before mating. Four days after mating embryos were recovered and scored for normality. Those which appeared to be normal were deposited into one uterine horn and the others were deposited into the opposite horn of a synchronous pseudopregnant recipient. Numbers of implantation sites and living fetuses were determined twelve days after mating.There was a significant (P<0.01) reduction in the proportion of ova which cleavedin vitrobut no difference due to incubation temperature. Four days after mating significantly (P<0.01) fewer of the embryos exposed to the higher temperature were classified as normal (49% and 45%vs87% and 74% for ova stressedin vivoorin vitro, respectively). Of the embryos classified normal, 96% and 91% implanted in the 21° and 32°C group, respectively. But 50% of the abnormal embryos also formed implant sites in the 32°C group, however, only 12% of these sites contained a viable fetus. The proportion of embryos forming implantation sites or viable fetuses depended upon the amount of stress that the embryo had been subjected to early in its development. Morphology of a 4‐day old embryo is not indicative of its ability for subse

ISSN:0022-104X    

DOI:10.1002/jez.1401700105

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

年代:1969

数据来源: WILEY

摘要:

AbstractA collection of 379 drawings ofD. simulansclaret gynandromorphs, kindly supplied to the authors by Dr. A. H. Sturtevant, was used in order to analyze the cell lineage of the adult cuticular structures. The marker phenotypes forked bristles or yellow body color were used to trace the male tissue. The degree of mosaicism within the different imaginal discs was used to estimate the number of blastoderm nuclei whose descendants form the primitive imaginal discs on each side. The estimates are 23 for the compound‐eye‐antennal discs, 12 for the wing disc, several for the first and second leg discs and perhaps 1 for each of the prothoracic, third leg and abdominal discs. The frequency with which two parts are separated by sex, one male and one female, is assumed to vary inversely with the closeness of their embryonic descent. In this way were constructed the morphogenetic maps of the relative locations on one side of the embryo of the presumptive head, thoracic and abdominal adult structures. Locations of the presumptive parts within the morphogenetic maps are the same as the relative positions of the parts on the adult surface. Arguments are presented to place the morphogenetic map on the three‐dimensional surface of the egg. The data are consistent with the model that the morphogenetic map of the prospective adult structures occupies a medial band along both sides of the embryo surface. Poulson's ('50) ground plan of the egg also places the presumptive larval hypodermis in this location. This model is considered relative to the experimental evidence marking the early embryo s

ISSN:0022-104X    

DOI:10.1002/jez.1401700106

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe free‐living nematodePanagrellus silusiaecan be grown synchronously through the postpartum period of its life cycle. This period is divided into four phases which in sequence are called the L2, L3, L4 and adult stages. Homogenates from each stage were analyzed electrophoretically in order to discover whether protein changes occur during postembryonic development. Protein patterns in acrylamide gels from L2, L3, L4 and adult stages show no differences in the number of bands (16), although there are differences in the intensity of certain bands at various stages.Definite stage specific patterns were observed when enzyme activity was assayed histochemically. L4 larvae show five sites of lactate dehydrogenase activity in polyacrylamide gel; three of these are found in each of the other stages. L3 larval extracts have five sites of malate dehydrogenase activity; L2 larvae and adults share one of these and L4 larvae have two in common. L4 and adult nematodes each have one MDH type not present in any other stage. L4 larvae produce six sites of α‐naphthyl acetate esterase activity; four of these bands are present in each of the other stages. Both acid and alkaline phosphatase occur as single molecular forms in each postpartum stage.It is concluded that during maturation a precise regulatory program operates to control the sequential appearance of specific enzymatic prot

ISSN:0022-104X    

DOI:10.1002/jez.1401700107

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

年代:1969

数据来源: WILEY

摘要:

AbstractNeuromuscular junctions formedin vitrohave been obtained previously only in cultures of cross‐sections of embryos. These have represented simply the further developmentin vitroof the anlage of neuromuscular junctions previously formedin vivo.The present experiments were designed to determine whether such junctions could formde novoin tissue culture and in organ culture from spatially separated spinal cord and skeletal muscle. Cultures of dissociated spinal cord and muscle cells could not be maintained sufficiently long to lead to differentiated neuromuscular junctions. However, when fragments of spinal cord and muscle from chick embryos of varying developmental stages were cultivated for several weeks neuromuscular junctions could be identified by phase contrast microscopy, silver impregnation, and AChE staining. The neuromuscular junctions were similar histologically and histochemically to those developingin viv

ISSN:0022-104X    

DOI:10.1002/jez.1401700108

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

年代:1969

数据来源: WILEY

摘要:

AbstractAdult, male hamsters, (Mesocricetus auratus, Waterhouse), were exposed to an environment of 5 C (2 months and 3 to 4 months) to investigate the effects of cold‐exposure and 2 to 5 days of hibernation on the following parameters: (1) body weights, (2) testes weights, (3) testes and brown fat histology and histochemistry, and (4) liver and brown fat mitochondrial succinate oxidation. Controls were maintained at room temperature. Only the hibernating animals lost a significant amount of weight during exposure. Although the testes regressed in both cold‐exposed and hibernating animals, the testes of hibernators showed some signs of recrudescence relative to the cold‐exposed non‐hibernators, as indicated by increased spermatogenic activity, slightly larger seminiferous tubules, greater organ weights, and the presence of PAS positive, diastase sensitive material. Brown fat in experimental animals had smaller and more numerous fat droplets per cell than the controls and nuclei which appeared to be more centrally located. Analysis of liver mitochondrial activity revealed the rate of succinate oxidation to be reduced in hibernators and increased in cold‐exposed non‐hibernators. Brown fat succinate oxidation was unaltered in both experimental groups. These results indicate that, early in the hibernation cycle, both physiological and morphological changes occur which distinguish hibernating hamsters from cold‐exposed hamsters which failed

ISSN:0022-104X    

DOI:10.1002/jez.1401700109

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

年代:1969

数据来源: WILEY

摘要:

AbstractPostnatal hamsters were examined for a metabolic response to cold by measuring oxygen consumption at ambient temperatures of 25°, 30°, 33°, and 36°C. In conjunction with this, colonic temperatures were recorded, and the animals were examined for brown adipose tissue development.During the first ten days of postnatal development hamsters increased their O2consumption linearly as ambient temperature was raised from 25° to 36°C. Thus, they are initially poikilothermic. Body temperatures were directly dependent on environmental temperature, and no mature brown fat deposits had yet developed.On days 11 and 12, O2consumption curves began to vary from a linear relation with ambient temperature, and small inflexions developed at 30° and 33°C. By postnatal days 14 and 15 maximal values were recorded at 25°C. Simultaneously, brown fat deposits developed definitive characteristics and body temperatures came to range only slightly below adult temperatures during exposure at 25°C.During the latter stage of maturation studied in these experiments, days 17 to 21, the animals achieved homeothermic stability between 25° and 36°C. Only 25°C prompted a metabolic increase, 30° to 36°C became a zone of thermal neutrality, and body temperatures came to equal or exceed adult temperatures. The animals had gained significant weight, thereby increasing thermal insulation, and brown fat deposits had accumulated ad

ISSN:0022-104X    

DOI:10.1002/jez.1401700110

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

年代:1969

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1401700101

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

年代:1969

数据来源: WILEY