bluuebunny/crossref_metadata_2025 huggingface dataset:
Micrurgical experiments on cytokinesis in Stentor coeruleus
Authors: Tartar Vance
Published: June 2005

Cutting and grafting experiments on the ciliate Stentor coeruleus during division stages indicated or demonstrated the following: (1) Unequal division after excision of one cell end showed that the location of the fission line usually remains predetermined but this line is not an indispensable constriction organelle. (2) The fission line is always smooth in spite of irregularities in the cell surface and it cannot extend across gaps. (3) A transequatorial piece of a divider can go on to divide anywhere on a divider in the same stage of division but its fission is not autonomous because it can be affected if the host cell is in a very different stage of division or is a non‐divider. (4) After removing half the presumptive or actual fission line or furrow a stentor can still divide along the line of healing. (5) Transverse cuts, though resembling a division line, do not serve for fission. These results suggest a morphogenetic hypothesis of cell division in Stentor.
Chronic skin graft rejection in the urodela. I. A comparative study of first‐ and second‐set allograft reactions
Authors: Cohen Nicholas
Published: June 2005

Unlike acute skin allograft reactions observed in most randomly breeding ectothermic and endothermic vertebrates, a basic pattern of intermediate to prolonged chronic skin graft rejection characterized the alloimmune response of representatives of at least five genera of salamanders from three different families (Salamandridae, Ambystomatidae, and Proteidae). First‐set median survival times (MST's) ranged from 33 to 55 days at 25°C. Individual zero end points (total melanophore destruction) occurred between 17 and 120 days. Several grafts appeared to have survived indefinitely (> 300 days) with full to partial viability.

MST's of second‐set grafts were significantly shorter than first‐set MST's for all salamanders except Ambystoma tigrinum. For this species, the small sample of seven repeat grafts all exhibited either prolonged survival vis‐a‐vis first‐set grafts or were destroyed well within the range of first‐set rejections. About 25% of the combined individual Taricha and Necturus repeat grafts were completely destroyed at the same postoperative time as or significantly later than first‐set grafts from the same donor. Only curtailed survival of Cynops second‐set grafts was noted. When the post transplantation period was resolved into a latent phase and a rejection phase, the curtailed survival of 50% of the Traricha and 60% of the Cynops second‐set grafts was attributable solely ot a comparatively shorter latent period. The curtailed zero end points of other Taricha repeat grafts resulted from both shorter latent and shorter rejection intervals. The overall prolonged second‐set survival noted for some Taricha allografts was referable only to longer rejection phases; the latent phases for these repeat grafts were either shorter than or similar to those of the corresponding primary grafts.
Reversible developmental arrest in the embryo of the zebrafish, Brachydanio rerio
Authors: Laale Hans W. , McCallion David J.
Published: June 2005

Zebrafish embryos at six developmental stages were exposed to the supernatant of homogenates of zebrafish embryos, 5‐day chick embryos and 9 mm frog larvae. Extracts of embryos bring about developmental arrest of the zebrafish embryo at stages 17–18. The effect is reversible. Arrested embryos returned to buffered water recover and develop normally to hatching, delayed by a time equal to the time of exposure to extracts. Two fractions of the embryo extract are produced by G‐75 Sephadex gel filtration. The inhibitory effect is limited to one of these fractions. The inhibitory factor in embryo extract has characteristics compatible with those of nucleases but the effect on embryos is unlike that of ribonuclease.
Mechanism of the pleiotropic effects of the short‐ear mutant gene in the mouse
Authors: Green Margaret C.
Published: June 2005

The recessive mutant gene short‐ear (se) reduces the rate of proliferation of precartilage cells, producing a skeleton of reduced size with numerous small defects. It also reduces the rate of proliferation of callus cells in healing bone fractures. In this study se was shown not to affect rate of regeneration of liver, thymus, or connective tissue.

Short‐eared mice have many anatomical abnormalities of the soft tissues including medial displacement of the left gonad, ventral displacement of the right renal artery, hydroureter and hydronephrosis, giant cell granulomas on the ventral surface of the liver, and on some genetic backgrounds an increased frequency of cysts of the lungs. Young se/se mice often have neuromuscular waviness of the tail. In the heterozygous condition (+/se) the gene causes a slight reduction in skeletal size and a slight increase in frequency of hydroureter, liver lesions, lung cysts, and wavy tail. It was shown that the viscera appear to be crowded from the 11‐day stage of gestation and that crowding is probably responsible for the abnormalities of the left gonad, the right renal artery, and the ureter, and is possibly a contributing cause of the granulomas of the liver. The probable cause of the crowding is the slower growth of the skeleton, resulting in a body cavity too small to accommodate the visceral mass of normal size. It is not clear that crowding is a sufficient explanation of the liver lesions or that it explains the effect of se on frequency of lung cysts or on waviness of the tail.
Oogenesis in the suppressor2 of hairy‐wing mutant of Drosophila melanogaster. I. Phenotypic characterization and transplantation experiments
Authors: Klug William S. , Bodenstein D. , King R. C.
Published: June 2005

Cytological studies of ovaries from Drosophila melanogaster homozygous for the female sterile gene, su2‐Hw, demonstrate that the nurse cell components of the egg chambers are primarily affected. The chromosomes of these endopolyploid cells remain condensed, whereas the normal polytene chromosomes of wild type nurse cells uncoil and fall apart prior to vitellogenesis. Vitellogenesis is greatly inhibited in the mutant, and the egg chambers eventually degenerate. Reciprocal transplantation experiments show autonomous behavior of + and su2‐Hw ovaries. Therefore the ovarian phenotype is due to the action of the mutant gene in the ovarian cells themselves.
Polar granules of Drosophila. II. Ultrastructural changes during early embryogenesis
Authors: Mahowald Anthony P.
Published: June 2005

Polar granules of Drosophila show distinctive variations in structure at various stages of early embryogenesis and in different species. In most species they are attached to mitochondria at fertilization, then they become free and fragment during the cleavage divisions and during the time of pole cell formation. After pole cells have formed they again coalesce. At the time of migration of the pole cells to the embryonic gonad, the polar granules again fragment and become attached to the outer membrane of the nuclear envelope.

Ribosomes are attached to the periphery of polar granules at the time they are fragmented prior to and during pole cell formation. An hypothesis is presented on the basis of published reports of RNA present in the granules and the ultrastructural observations reported here. This hypothesis suggests that the RNA in polar granules is m‐RNA that directs the synthesis of those proteins necessary for the determination of the pole cells to become germ cells.
Histological and ultrastructural study of the muscular and nervous systems in Hydra. I. The muscular system and the mesoglea
Authors: Haynes Julian F. , Burnett Allison L. , Davis Lowell E.
Published: June 2005

The myonemes of the epithelio‐muscular cells of Hydra viridis were studied with the electron microscope. The myonemes are formed from fibers running parallel to the long axis of the polyp. The myoneme is a mixture of thick (200 Å diameter) filaments and thin (60 Å diameter) filaments. There was no indication of regular organization or spacing of the filaments. The filaments were attached to the membranes of the epithelio‐muscular cells at their ends. In these regions there were junctions between adjacent cells similar to the intercalated discs of vertebrate cardiac muscle. The possible role of these junctions in the transmission of an impulse along the length of the body column is discussed.

The mesoglea consists of organized fibers dispersed in an amorphous ground substance. The pattern of organization of the fibers of the mesoglea is possibly a spiral and may be responsible for some of the morphogenic phenomena in Hydra which follow a spiral pattern.
Quantitative evaluation of individual variability in the heat‐resistances of cells and their contractile models
Authors: Ushakov B. , Amosova I. , Pashkova I. , Chernokozheva I.
Published: June 2005

Evaluation of thermostability by the time required to inactivate cells and models at a constant temperature reveals significant differences between specimens from the same population.

The analysis of statistical distribution of the thermostabilities of cells and cellular models shows that it is advantageous to treat the logarithms of the inactivation times rather than the numerical values themselves. (a) The distribution curve in this case is symmetric while that of the numerical values for some of the objects studied is an asymmetric one, and (b) the value of variance of logarithm distribution does not depend on the temperature at which the heart‐resistance is measured.

Standard deviation or distribution variance of logarithms of inactivation times of cells and models may be used as quantitative criteria of intrapopulational variability in heat‐resistance. When comparing variabilities in the heat‐resistance of non‐homologous cells and models, special attention should be paid to the possible effect of methodological factors on the total magnitude of the variance or standard error.

Frequency curves of the thermostabilities of cells and models exhibit only a single maximum and have a continuous character which may indicate polygenic inheritance of heat‐resistance.
Correlated physiological and ultrastructural studies on specialised muscles. Ic. Neuromuscular junctions in the eyestalk levator muscles of Podophthalmus vigil (Weber)
Authors: Hoyle Graham , McNeill Patricia Ann
Published: June 2005

The ultrastructure of physiologically different motor nerve terminals on fibers of the eye‐raising muscle of the crab Podophthalmus vigil is described. The terminals occur wherever branching axons lose part or all of their Schwann cell cover, either in simple grooves on the surface, in invaginated clefts, or even deep within the fiber in invaginated fingers lined by extension from the surface plasma membrane of the muscle fiber. Dense innervation of the surface of the fiber is associated with the occurrence of large, non‐facilitating e.p.s.ps., i.e., with “fast” axons. Less dense innervation, with deeply invaginated terminals is associated with small‐sized e.p.s.ps. and with facilitation typical of “slow” axons. No differences in either vesicle content, vesicle shape, mitochondrial density or density of other particles could be found in terminals having different associated biophysical properties.
Effect of calcium on the structure and functional response of the starfish ovary to radial nerve factor
Authors: Schuetz Allen W. , Biggers John D.
Published: June 2005

The effects of calcium‐free sea water (CaFSW) on the starfish ovarian structure and on ovarian responsiveness to radial nerve factor (RNF) were studied following in vitro incubation. Incubation of ovaries in CaFSW resulted in a progressive elongation of the entire ovary and the dispersion of follicular cells from around the oocytes contained within the ovary. The changes in ovarian length but not the follicular cell detachment were reversible when ovaries were placed in sea water containing calcium. Addition of Mg++ or Na+ to CaFSW did not prevent ovarian elongation or follicular cell dispersal. Strontium ions prevented and reversed ovarian elongation when added to CaFSW; however, follicular cell dispersion was not inhibited. The oocyte shedding, normally induced by RNF, was prevented by maintaining the ovary in CaFSW. The degree of shedding inhibition was dependent upon the duration of washing in CaFSW. RNF did not prevent or reverse the ovarian elongation induced by CaFSW. The inhibitory action of CaFSW on RNF‐induced oocyte shedding could be reversed by the addition of Ca++ or Sr++ but not by the introduction of Mg++ or Na+. The degree of reversibility was dependent upon the concentration of Ca++ ions. The data strongly indicate that contractile tissue in the ovarian wall is important in mediating oocyte shedding in response to RNF.
Genic control of cortical pattern in Euplotes
Authors: Heckmann Klaus , Frankel Joseph
Published: June 2005

Three inter‐fertile wild races of Euplotes minuta, which differ with respect to the maximal number of kineties expressed in a clone, were subjected to a breeding analysis. The data obtained in this analysis suggest a genic control of the differences in cortical pattern. Evidence for the operation of a cytotactic mechanism for short‐term perpetuation of kineties was also obtained.

Investigation of cellular features, possibly related to the mode of action of this genic control, established no direct relationship between kinety number and fission rate or cell size. Some evidence was, however, found for a genic control of the total number of kinetosomes, and this might be related to the control of the number of kineties. A mechanism, by which kineties are gained and lost, is proposed and evidence for this mechanism is provided.

The relation between cytotaxis and the genic control of the range of kinety number is discussed, and the conclusion is reached that cytotaxis helps to perpetuate existing surface patterns, whereas long‐range control of the most stable kinety number is nevertheless genic.
Effect of short‐ and long‐term hypophysectomy on the ovary and interrenal of catfish, Heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Goswami Shashi V.
Published: June 2005

Catfish were hypophysectomized during the late prespawning period when the ovaries are enlarged with yolky oocytes, and autopsied at close intervals to ascertain the short‐term effects of hypophysectomy. A significant reduction in the ovarian weight occurs between day 4 and day 6 post‐hypophysectomy. Thereafter, the ovarian weight declines rapidly and the lowest value is attained by day 35 post‐hypophysectomy. Hypophysectomy induces atresia of yolk‐laden oocytes and the sequence of changes in an atretic oocyte involves the coalescence of yolk plateletes, breakdown of vitelline membrane, hypertrophy of granulosa cells which quickly phagocytose the yolk, and the eventual merger of masses of granulosa cells in the ovarian stroma. Hydration of the ovaries gradually increases following hypophysectomy and the maximum value is attained by day 19 post‐hypophysectomy when follicular atresia is greatest, and returns to normal by day 49. Hydration of muscles remains almost constant despite hypophysectomy. In the interrenals, the post‐hypophysectomy changes involve leucocytic infiltration, gradual reduction in the nuclear diameter of cortical cells and condensation of chromatin.

In the long‐term study, catfish were hypophysectomized during the preparatory period when the ovaries are regressed, and autopsied one and two years post‐hypophysectomy. The ovarian histology of catfish sampled one and two years following hypophysectomy was similar to that of their respective controls inasmuch as sampling was also done in the preparatory period, whereas the interrenal histology was markedly different from that of the controls. In the interrenals of hypophysectomized groups, leucocytic infiltration was more in evidence and the cortical cell nuclear diameter showed significant reduction.
Cytological and ultrastructural comparisons of t12/t12 and normal mouse morulae
Authors: Calarco Patricia G. , Brown Edward H.
Published: June 2005

Cytological and ultrastructural observations were made of normal (BALB/c) mouse morulae and embryos homozygous for the t12 mutation, which is lethal at the late morula stage. Normal and t12/t12 embryos are indistinguishable cytologically until the late morula stage, at which time cytoplasmic and nuclear differences become apparent. Different cells within individual normal morulae exhibit differences in cytoplasmic basophilia, and the cells appear closely applied to one another. Differences in cytoplasmic basophilia are not apparent between different cells of t12/t12 morulae, and the cells appear more rounded and less closely applied. Nucleoli of normal morulae are irregular in shape, with projections which often reach the nuclear envelope, while nucleoli of t12/t12 morulae exhibit extreme rounding.

Nucleoli of normal embryos exhibit a net‐like nucleolonema, with fibrillar and granular elements, and several pars amorpha. Nucleoli of t12/t12 morulae possess the same structural elements but the nucleolonema appears contracted. Nuclei of mutant embryos often contain several agranular electron‐dense bodies, 0.1–0.7 μ in diameter. These are infrequently observed in normal morulae. Ribosomes exist primarily in clusters in normal morulae, but large numbers of free ribosomes are observed in t12/t12 morulae. Many structures are common to both normal and mutant morulae, such as: fibrous strands, crystalloids, granular endoplasmic reticulum, vacuolated mitochondria, cytoplasmic vesicles, tight junctions, nuclear pores, and intranuclear annulate lamellae.

Since the abnormalities exhibited by t12/t12 morulae can be interpreted as degenerative changes, they do not resolve the mode of action of the t locus or the primary cause of t12/t12 lethality.
The fate of desmosomes in trypsinized tissue
Authors: Overton Jane
Published: June 2005

Embryonic animal epithelial tissue in which desmosomes are well developed has been dispersed by trypsinization and the behavior of desmosomal halves observed. An earlier report left open the question of whether desmosomes were broken down or reincorporated into the reorganized tissue. A more detailed study shows that dispersed cells, or cells which are partially separated, phagocytize half desmosomes left at the cell surface. The resulting vacuoles are angular during early stages of the process indicating that desmosomes are relatively rigid. They later become spherical and characteristic desmosomal morphology disappears. These results are discussed in connection with morphology in genetic disturbances and in development.
A yellow variant of the eumycetozoan Didymium nigripes which exhibits aging
Authors: Kerr Norman S. , Waxlax Judith N.
Published: June 2005

A 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 predictable.
Blastular arrest and chromosome abnormalities produced by x‐rays in two amphibians: Rana pipiens and Xenopus laevis
Authors: Ursprung Heinrich , Leone Janet , Stein Louis
Published: June 2005

Production 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 arrest.
Experimental studies on hatching behavior in the chick. II. Extirpation of the right wing
Authors: Narayanan C. H. , Oppenheim Ronald
Published: June 2005

The 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 wing.
Effect of castration on muscle growth in the mouse
Authors: Rowe R. W. D.
Published: June 2005

Male 129/Re mice were castrated at 18–24 days of age. At 20 weeks of age they were sacrificed and the body weights and the weights of the anterior tibialis, biceps brachii, extensor digitorum longus, soleus and sternomastoideus were recorded. These muscles were also examined cytologically for total fiber number and fiber diameter distributions. The differences between the muscle weights of castrates and controls were correlated with different levels of fiber growth. The level of fiber growth in the phasic anterior tibialis, biceps brachii and extensor digitorum longus (i.e. muscles bringing about body movements) was concluded as being under the indirect control of the pituitary growth hormone, in that it acts on the body as a whole thereby increasing the work load of these muscles. Whereas for the sternomastoideus there appears to be a more direct effect of testosterone.
Acetylcholinesterase and choline acetyltransferase activity in the developing chick spinal cord
Authors: Burt Alvin M.
Published: June 2005

Microchemical procedures were employed for the quantitative assay of acetylcholinesterase (AChE) and choline acetyltransferase (ChAc) activity in the brachial spinal cord of chick embryos from 3.5 to 21 days' incubation. The activity of AChE increased nearly 10‐fold during the 60‐hour period from stage 22 (3.5 days) to stage 30 (6.0 days). The level of AChE at six days was essentially the same as that at hatching. During the intervening period, the level of AChE activity remained unchanged with the exception of minor transient peaks at days 7, 13, and 18. The activity of ChAc increased 22‐fold during the developmental period studied. The onto‐genetic pattern was characterized by two periods of rapid increase in acitvity. From stage 23 (3.75 days) to stage 31 (7.0 days), ChAc activity increased approximately 5.4‐fold and from stage 38+ (12.5 days) to stage 44, (18 days) ChAc activity increased approximately 3.6‐fold with the major increase occurring during the 48‐hour period from stage 42 to stage 44. The ontogenetic patterns for both enzymes are discussed in relation to morphological and functional differentiation. It is suggested that ChAc activity is a more reliable index of functional differentiation than is AChE and that the initial increase in AChE activity may be associated with some function other than synaptic transmission.
Temporal pattern of macromolecular events during the microstome‐macrostome cell transformation of Tetrahymena vorax strain V2S
Authors: Buhse Howard E. , Cameron Ivan L.
Published: June 2005

Differentiation of cell type can be experimentally controlled in the ciliated protozoan Tetrahymena vorax. If an early stationary growth phase population of small‐mouthed saprozoic cells (called microstomes) is washed and suspended in a transforming principle, stomatin, (which is released by a potential prey, i.e., Tetrahymena pyriformis), the microstomes transform into a population of large‐mouthed potentially carnivorous cells (called macrostomes). This process is observed by four and one‐half hours after stomatin addition. During cell transformation the pattern of DNA, RNA and protein synthesis were measured by autoradiographic and chemical techniques.

Microstomes undergo macrostome formation with a net synthesis of cellular protein and RNA. Autoradiographs demonstrate that no new cells enter DNA synthesis during the first four hours of cell transformation. Isotope labeling and chemical data demonstrate that RNA synthesis is stimulated by stomatin and reaches a peak at about 150 minutes; increased protein synthesis lags somewhat behind RNA synthesis and does not reach a peak until 210 minutes. The increased synthesis of RNA and protein is associated with disaggragation of fused nucleoli into individual nucleoli. The disaggregation of fused nucleoli and the associated increases in RNA and protein synthesis appear necessary for the ensuing morphogenetic events which lead to macrostome formation. Apparently stomatin is serving as a relatively rich source of nutrient.
The influence of neural tissue on the early development of somitic muscle in ventrolateral implants in Ambystoma
Authors: Muchmore William B.
Published: June 2005

Prospective somite mesoderm from both sides of an Ambystoma neurula was implanted under the flank ectoderm of another embryo at stage 20–22. The host was fixed and studied after a period ranging from ten days to three months. After ten days to two weeks of culture there was good differentiation of muscle in the implants, just as in explants of the same amount of presumptive somite mesoderm into an ectodermal jacket. Subsequent to this, the muscle cells which had differentiated began to degenerate, and after a month or more only a trace of muscle, or none at all, was found. When presumptive spinal cord was included with such implants, initial differentiation of muscle was similar histologically and quantitatively, but the muscle cells were better organized into myotomes than in the first experiment. In these cases, also, the quantity of muscle in the graft tended to decrease after two weeks, but then increased again by two or three months. The results are interpreted as indicating that the developing spinal cord has little effect on the initial differentiation of muscle cells, but then, after about ten days, the outgrowing nerves exert an important influence on the maintenance and further growth of the myotome.
Effect of thyroxin on the gonad and body weight of Spotted Munia, Uroloncha punctulata
Authors: Thapliyal J. P. , Garg R. K. , Pandha S. K.
Published: June 2005

Low doses of l‐thyroxin promote feather regeneration and lead to significant reduction in the mean weight of the gonad of adult normal and thyroidectomized Spotted Munia, Uroloncha punctulata, in the breeding phase. At moderately high doses of thyroxin complete molting occurs, and the mean weight of the gonoduct is also significantly reduced. The effect of l‐thyroxin increases as the duration of administration is increased. There is practically no difference between the response of normal and thyroidless birds.

It is suggested that whereas the effects of l‐thyroxin on the plumage are by way of body metabolism, those on the gonad, gonoduct and body weight are due to a direct influence on the output of the gonad‐stimulating and growth‐promoting hormones from the adenohypophysis.
Subsequent development during incubation of fertilized mouse ova stressed by high ambient temperatures
Authors: Elliott D. S. , Burfening P. J. , Ulberg L. C.
Published: June 2005

Mouse embryos subjected to high temperature stress (heat‐stress) in vivo during the time of first cleavage division, were recovered from the oviducts 48 to 54 hours post‐observance of a copulatory plug. The effects of heat‐stress on development of those embryos incubated in vitro through the blastocyst stage were studied and compared to embryos from mice in a control environment. Heat‐stressed embryos which developed in vivo to ten days gestation were also studied.

Development of heat‐stressed embryos was retarded by the time of recovery. There was a significant (P<0.05) decrease in the number of heat‐stressed embryos which became blastocysts in vitro, as compared to control embryos. Also, there were fewer blastocysts from heat‐stressed embryos which hatched during three days of incubation in vitro when compared to controls (56% vs 67% for heat‐stressed and controls, respectively). There was significant (P<0.01) pre‐ and post‐implantation loss of embryos in heat‐stressed females at ten days gestation.
Gross morphology and predictability for survival of 4‐day rabbit embryos following heat‐stress during the first cleavage division
Authors: Burfening P. J. , Alliston C. W. , Ulberg L. C.
Published: June 2005

Rabbit embryos were subjected to heat‐stress during the first cleavage division. Those embryos to be heat‐stressed in vitro were 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‐stressed in vivo by 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 cleaved in vitro but 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% vs 87% and 74% for ova stressed in vivo or in 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 subsequent survival.
Cell lineage of the imaginal discs in Drosophila gynandromorphs
Authors: Garcia‐Bellido A. , Merriam J. R.
Published: June 2005

A collection of 379 drawings of D. simulans claret 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 stages.
Effects of cold exposure and hibernation on the liver, brown fat, and testes from golden hamsters
Authors: Frehn John L. , Thomas Joseph A.
Published: June 2005

Adult, 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 to hibernate.
Insect neurometamorphosis. IV. Effects of the brain and synthetic α‐ecdysone upon interganglionic connective shortening in Galleria mellonella (L.) (Lepidoptera)
Authors: Pipa Rudolph L.
Published: June 2005

The interganglionic connectives of pharate pupae and pupae < 5 hours after ecdysis (early pupae) of Galleria mellonella will cease shortening if the segments in which they lie are separated from the prothorax. Though shortening is not prevented by removing the brain of an early pupa, it will be delayed several days. This period is prolonged to more than a week if the corpora cardiaca (Cc) and corpora allata (Ca) are removed together with the brain. The retardation induced by extirpating all three organs is prevented by implanting a single brain from a pupa or an adult, but not by implanting ganglia. It is also alleviated, to a lesser extent, by one or two pairs of Cc‐Ca.

As many as three brains transplanted into a posterior pupal fragment deviod of acknowledged endocrines will not initiate shortening, but implanting a single brain into a decerebrated anterior fragment will. The evidence suggests that the brain does not regulate shortening directly. Instead, it may do so by producing prothoracotropic hormone.

Approximately 0.03 μg of synthetic α‐ecdysone per animal is sufficient to cause 50% of the meso‐metathoracic connectives of brainless pupae to shorten half their initial length or more within three days. For posterior pupal fragments, however, ca. 0.06 μg per animal is required. The sensitivity of this developing system to ecdysone parallels its responsiveness to transplanted brains, and the shortening nerve cord may be useful in assaying for brain hormone.
Latency relationships between loosely coordinated locust flight motor neurons
Authors: Waldron Ingrid , Wilson Donald M.
Published: June 2005

During flight the pattern of activity of the motor neurons of the locust wing muscles is normally a precisely controlled score. The elevator motor neurons are active in short synchronous impulse bursts and these alternate with similar bursts in the depressor motor neurons. In experimental preparations the normal coordination may break down, so that electrical stimulation of the nerve cord may elicit a very poorly coordinated response. In these cases, a histogram of the relative latencies of activity in two synergistic elevator motor neurons typically shows three modes, indicating that relative latency tends to assume values near 0 msec, about 6–8 msec, and about 25–35 msec. Simultaneous responses to common input play a major role in causing the peak at 0 msec. Excitatory synaptic interactions between motor neurons, or interneurons which drive them, appear to be responsible for the peak at 6–8 msec. The longest latency peak may be due to firing upon recovery from long‐term inhibitory interactions between the synergistic motor neurons. The short‐term excitatory feedback interactions between synergistic motor neurons probably are important for the production of the multiple firing in the impulse burst during flight. Long‐term inhibitory interactions may limit the activity in this positive feedback system and play a role in terminating each burst.
Altered contact behavior of presumptive mesodermal cells from hybrid amphibian embryos arrested at gastrulation
Authors: Johnson Kurt E.
Published: June 2005

Contact behavior of presumptive mesodermal cells taken from normal amphibian embryos, hybrid embryos, and hybrid embryos arrested at gastrulation was investigated. Normal cells have a high ability to flatten on a glass substratum and reaggregate. Cells from a viable hybrid which shows some abnormalities in invagination have an intermediate ability to flatten on a glass substratum and an undiminished ability to reaggregate. Cells from three different types of hybrid embryos arrested at gastrulation have a low ability to flatten on a glass substratum and reaggregate. The implications of these results for hypotheses concerning mechanisms of morphogenetic cell movements are discussed.
Skin allograft and xenograft rejection in the snapping turtle, Chelydra serpentina
Authors: Borysenko M.
Published: June 2005

The immune response of the snapping turtle, Chelydra serpentina, to skin allografts and xenografts at several environmental temperatures was studied. Xenografts were supplied by the painted turtle, Chrysemys picta, and the Blanding turtle, Emys blandingii. Gross and microscopic manifestations of rejection were observed. Beginning of graft death and total graft death marked two survival end points. The first of these events was used in statistical comparisons of mean survival times of grafts of the various series, which included a total of 107 host animals involving 74 allografts and 76 xenografts.

Skin autografts survived through the periods of observation with no morphological evidence of incompatibility. Using gross and histological survival end points, which indicated the beginning of graft death, first‐set allografts were rejected in about 40 days; second‐set in about 21 days, at 25 ± 1°C. Allografts from young snappers survived slightly longer.

Xenografts from both donor species were rejected after nearly the same survival times. First‐set xenografts were rejected in about 24 days; second‐set xenografts in about 16 days, at 25 ± 1°C. Painted turtle skin xenografts on snappers which had previously received painted turtle tissue in transplantation between embryos, survived significantly longer, about 36 days.

There was no morphological evidence of rejection of first‐set allografts of xenografts for the observation period of 100 days, at 10 ± 1°C. Allografted snappers that were transferred to 25 ± 1°C, rejected the grafts about 30 days after the transfer.

First‐set allografts were rejected much faster at 33 ± 1°C, in about 24 days, as were first‐set xenografts, in about 17 days.
The maturation of the capacity to reject skin allografts and xenografts in the snapping turtle, Chelydra serpentina
Authors: Borysenko M.
Published: June 2005

Skin allografts and Blanding skin xenografts were transplanted to young snapping turtles ranging in age from newly‐hatched to six months. In this study, involving 88 skin allografts and xenografts, it was shown that the snapping turtle matures immunologically in its capacity to reject grafts several months after hatching. It takes newly‐hatched turtles over 90 days to reject skin allografts and xenografts. The survival times are nearly half that when the animals are only one month of age. Mean survival times then drop a few days with each month of age. By four to six months, snapping turtles reject skin allografts and xenografts at about the same rate as do adult snappers. Skin xenografts were rejected faster than allografts at every age after the newly‐hatched series. There were some cases of very extended sibling skin allograft survival during the early months posthatching. A later series involving older animals showed that sibling allografts were rejected at nearly the same rate as non‐sibling allografts.
Electroencephalographic episodes of 1 to 7 per second rhythmic waves following hypothermic hypoxia in developing chicks
Authors: Peters Joseph J. , Vonderahe Alphonse R. , Hilgeford Eric J.
Published: June 2005

Developing chicks between the day of hatching and three weeks after hatching were subjected to hypothermia of 20°C followed by nitrogenous hypoxia until breathing ceased and the cerebral electroencephalogram was reduced to zero potential. Resuscitation was started 15 minutes later; 86% of the chicks resumed spontaneous breathing. Eighty percent of the resuscitated chicks showed electroencephalographic episodes usually lasting 1 to 3 minutes and consisting of conspicuously rhythmic blunt spike‐like waves of large amplitude and complex patterns with frequencies in the range of 1 to 7 waves per second until the episode was terminated at almost zero potential. Monopolar techique using the comb as the reference electrode indicated that the EEG episodes were either predominantly bilateral or unilateral, with both gradual and abrupt changes in amplitude, frequency, and site of origin. During episodes the chicks were either motionless or showed tremors of eyelids, limbs, trunk, with occasional staring and chirping. During progressive recovery, as episodes approached, large amplitude waves increased in amplitude and frequency, and changed from domes to blunt spikes. Similar slow waves apeared during episodes and continued during recovery eventually culminating in normal EEG patterns of sleep. Statistically the younger chicks showed briefer and fewer episodes, with the lowest maximum frequency. On the day following experimentation 86% of the resuscitated chicks were alive and showed normal EEG patterns and behavior: death was not limited to chicks having episodes.
The functional development of the reticulo‐endothelial system in the toad, Xenopus laevis (Daudin)
Authors: Turner Rodney J.
Published: June 2005

The development and extent of the phagocytic system in larval and adult Xenopus was determined by injections of colloidal carbon by various routes, followed by dissection and/or histological examination. It was shown that in young tadpoles of stage 48 (aged 7.5 days at 23°C), the small population of pericardial and peritoneal macrophages alone was responsible for phagocytosing intraperitoneally injected carbon. In later stages this population of macrophages in greatly increased, and the tubule cells of the pronephros and mesonephros are capable of ingesting both carbon and mammalian erythrocytes drained from the body cavity. Attention was drawn to a possible relationship between this localization of foreign material in the open kidney, and the lymphoid accumulations found there in Xenopus and other lower vertebrates.

Blood‐ and lymph‐borne particles were removed mainly by cells of the spleen and liver in both tadpoles and adults: no phagocytic organs which could be described as lymph nodes were found at any stage. The findings suggest that the reticulo‐endothelial system of Xenopus is more primitive than that of Rana or Bufo.
The effects of nerve growth factor on the spinal ganglia of Ambystoma maculatum
Authors: Weis Judith Shulman
Published: June 2005

Nerve growth factor (NGF) isolated from mouse submaxillary glands was injected three times weekly into late embryos and young larvae of Ambystoma maculatum for a period of three weeks, producing an enlargement of the spinal ganglia owing to hyperplasia. This hyperplasia corresponds to the method of normal growth of ganglia at this late embryonic period of development, which is similarly one of cell multiplication rather than cell enlargement. The response of animals kept in the cold (12°C) during the experimental period, and which had reached Harrison stage 41 by the end of the experiment, was of doubtful significance, contrasted with that of animals maintained at room temperature and which had become 15 mm larvae by the end of the experiment. The latter group showed an increase in ganglion size of 100% over controls. The difference in magnitude of response of the two groups is believed to be due to the existence of a limited period in development when the animal is sensitive to NGF. The slowly developing animals in the cold had probably just reached the sensitive period by the end of the experiment, thus accounting for their small response compared with that of the animals which were allowed to develop further.
The ear of the chameleon: The round window problem.
Authors: Wever Ernest Glen
Published: June 2005

An examination of serial sections of the ears of several specimens of Chamaeleo senegalensis and Chamaeleo quilensis gives support to an earlier suggestion that these ears function by means of a substitute round window. The usual type of round window is absent, but there is a tortuous pathway leading from the scala tympani through the perilymphatic recess and then along the foramen of the glossopharyngeal nerve to the air cavity of the middle ear.

This pathway makes possible a mobilization of the cochlear fluids in response to sound pressures exerted at the oval window by the columellar footplate. However, the mechanism is somewhat inefficient; the frictional resistance along the pathway reduces the amplitude of cochlear motion. The relatively poor sensitivity of these chameleon ears is thus largely accounted for.
Aster‐equatorial surface relations and furrow establishment.
Authors: Rappaport R.
Published: June 2005

Flattened eggs of the sea urchin Hemicentrotus pulcherrimus were used in experiments designed to determine whether furrow establishment depends upon any particular geometrical relationship between the asters and the equatorial surface. In normal eggs at first cleavage the asters are 29.5 μ apart and the distance from the spindle center to the equatorial surface is 47.3 μ. In flattened eggs, the mitotic apparatus was pushed to an excentric position. The maximum spindle‐to‐surface distance that permitted furrowing was 62.5 μ. At second cleavage the spindle‐to‐surface distance is normally 36.2 μ but furrows develop when the distance is as great as 47.5 μ. The interastral distance and spindle‐to‐surface distance were varied simultaneously in flattened, dispermic eggs containing four asters. The activity of supernumary sperm asters was not detectably different from that of the mitotic apparatus. If the interastral distance was 32.5 μ furrows formed when the spindle‐to‐surface distance was between 32.5 μ and 47.5 μ. When the interastral distance is increased to 35 μ or more at the same spindle‐to‐surface distances, furrowing was rare. Very short spindle‐to‐surface distances were produced by perforating the flattened cells. They allowed study of combinations involving large interastral distances and short spindle‐to‐surface distances. Under this circumstance asters 35 μ or farther apart invariably elicited furrows when the spindle‐to‐surface distance was 20 μ or less. Decreasing the spindle‐to‐surface distance remedies a deficiency occasioned by abnormally great interastral distances. These results are considered to support the view that furrow establishment requires conjoint action of a pair of asters upon equatorial cell surface.
Some aspects of tail regeneration in the lizard, Anolis carolinensis. II. The role of the peripheral nerves,
Authors: Cox Prentiss G.
Published: June 2005

The work reported here affirms that the ependyma supports tail regeneration and demonstrates that the peripheral nerve supply makes no essential contribution to the regenerative process. The normal peripheral nerve supply in the tail of Anolis carolinensis was found to be 4.5 fibers per (100 μ)2. In tails in which the peripheral nerve supply was reduced to 0.34 fibers per (100 μ)2 normal regeneration occurred if the ependyma was present. In the absence of the ependyma (i.e., the central nervous system) but with 50–75% of the peripheral nerves present no normal regenerative outgrowth occurred; however, three or four myomeres were regenerated.