bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lens development. V. Histological analysis of the mechanism of lens reconstitution from implants of lens epithelium
Authors: Coulombre Jane L. , Coulombre Alfred J. 
Published: June 2005

AbstractA piece of five‐day embryonic lens epithelium was implanted in place of the right lens in each of 89 five‐day‐old chick embryos. The steps in the reconstitution of whole lenses from these grafts were identified by histologic analysis. Immediately following the implantation of the lens epithelium large numbers of cells came out of the anticapsular surface. Many of these died. Some of the survivors adhered in groups to the anticapsular surface of the implant. The cut edges of the implant became reflected so that the capsular surface was bent convexly. The reflected epithelium joined the groups of cells adhering to the anticapsular surface of the implant to form a flattened vesicle. The Golgi apparatuses of these cells lay at the anticapsular poles. The basal (capsular) poles of the cells always came to lie outermost regardless of the initial orientation of the implant. In time the vesicle filled the orifice of the eye cup and the reconstituted lens vesicle became invested externally by a continuous sheet of lens capsule. The cells in the wall of the vesicle that lay toward the vitreous body elongated to form lens fibers. A lens equatorial zone appeared facing the edge of the eye cup regardless of the orientation that had been given the implant initially. Thus, all of the reconstituted lenses were properly oriented in the eye.
The production of congenital defects in rats using antisera
Authors: Barrow Mark V. , Taylor W. Jape 
Published: June 2005

AbstractPregnant Long‐Evans rats were injected intravenously with antisera to adult kidney, placenta, lung, heart, fetal kidney and fetal thymus on various days of gestation in doses from 1 to 3 ml/100 gm of rat. Control animals showed a resorption rate of 6.6% with a malformation rate of 2.6%.Antisera to adult kidney and placenta given on the ninth, tenth and eleventh gestational days decreased fetal weights, increased resorption rates to greater than 50% and resulted in a malformation rate of 75% or greater. Malformations were observed in most organ systems depending on the day the antiserum was injected. Antisera to fetal kidney and adult lung produced similar responses but larger doses were required while antisera to adult heart and fetal thymus tissues demonstrated little effect. Purified antisera (gamma G) and pepsin digested gamma G evoked a teratogenic response. Antiserum to glomerular basement membrane was also teratogenic.These results support the concept that the mechanism of action of teratogenic antisera is an interference with yolk sac transport by adversely affecting the basement membrane of the yolk sac primarily and indirectly producing malformations.
Inhibition of pupation due to crowding in some tenebrionid beetles
Authors: Tschinkel Walter R. , Willson Clyde D. 
Published: June 2005

AbstractPupation of mature larvae of several species of tenebrionid beetles is inhibited by crowding. The magnitude of the inhibition varies according to species. The primary factor causing this inhibition is the mechanical stimulation resulting from inter‐larval contacts. Cannibalism of prepupae, pupae and teneral adults is discussed as the probable chief factor responsible for the evolution of the inhibitory effect of crowding.
The origin and possible genetic control of new, stable pigment patterns in the poeciliid fish Xiphophorus maculatus
Authors: Kallman Klaus D. , Schreibman Martin P. 
Published: June 2005

AbstractX. maculatus is polymorphic for sex‐linked macromelanophore patterns. Fish of different river systems exhibit identical markings, but they have a different genetic basis. The macromelanophore factors give rise to a population or species‐specific pattern only within their own gene pool. Crosses involving XsdYsr males of the Jamapa stock (Jp) gave rise to 3305 progeny — all but one either Sd or Sr. In the exceptional male Sd (spotted‐dorsal) became linked to Sr (stripe‐sided), SrSd. The dorsal fin of this fish and all of its SrSd descendants (5 generations) was almost solid black and heavy spotting was present in the caudal fin. There was no change in expression of Sr. Jp fish with Xsd Ysr, by comparison, possess from one to six well defined spots in the dorsal fin and a clear caudal fin. After introduction into the Hondo stock of X. maculatus Sd of Jp exhibits zero penetrance; the expression of Sd linked to Sr becomes greatly reduced. Thus the changes in gene expression go in the same direction. However, Sd and SrSd behave differently after introgression into X. couchianus. Sd is completely suppressed while Sd linked to Sr gives rise to melanotic and melanomatous dorsal and caudal fins. A similar alteration in gene expression towards a more extreme phenotype has also been observed among the offspring of a Jp Xsp Ysr male in which Sp and Sr became apparently linked. It is postulated that a modifier is closely linked to the macromelanophore factor that regulates its expression. The new phenotype is due to the separation of the two genetic elements. According to this view the phenotype that is expressed when a macromelanophore gene is introduced into a foreign genotype, is primarily determined by the modifier.
The strategy of tail‐autotomy in the Ground Skink, Lygosoma laterale
Authors: Clark Donald R. 
Published: June 2005

AbstractThe adaptation of tail‐autotomy is paradoxical in lizards which utilize the tail as a major fat‐storage organ, because high rates of tail‐loss are normal and because surrender of large fat reserves seems to amount to selective pressure favoring predation on such lizards. Experimental results demonstrate the existence of ta behavioral mechanism in Lygosoma laterale consisting of return by the lizard to where its tail was lost, a strong ingestion response to an inanimate automized tail, and movements by the autotomized tail which make its capture less likely. Laboratory evidence includes rates of ingestion of autotomized tails averaging nearly 40% for five species of skinks. This contrasts with rates averaging 3.4% for two iguanid lizards in which fat reserves are not stored in the tail. Tests with free‐ranging L. laterale show that ingestion occurs in nature. Additional laboratory experiments quantitatively demonstrate escape behavior by tails of L. laterale. The results confirm a behavioral mechanism in L. laterale which compensates for the ready autotomy of major fat reserves. At the same time, two divergent evolutionary strategies of adaptation of the autotomic tail are defined.
Mating refusal in Musca domestica: Effects of repeated mating and decerebration upon frequency and duration of copulation
Authors: Leopold R. A. , Terranova A. C. , Swilley E. M. 
Published: June 2005

AbstractThe loss of sexual receptivity displayed by once‐mated female house flies, Musca domestica L., was investigated by repeatedly mating males to deplete the accessory secretion responsible for inducing this behavior. With each successive mating, there was a step‐wise increase in the amount of time spent in copulo and in the number of females remating that were first crossed with previously mated males. Mating pairs containing males that had copulated three times before remained in copulo about twice as long as pairs containing virgin males. The remating of females initially crossed with virgin males was 3% as compared to 21% for those females crossed with males that had mated three times previously. These phenomena are apparently related to the titer of male accessory secretion reaching the receptor site(s) in the female that induce mating refusal behavior. The brain of the female apears to have some control over the loss of mating receptivity since mating inhibition was not displayed by females that had been decapitated or had their brains destroyed.
Studies on hydroid differentiation. VI. Regulation of hydranth formation in Podocoryne carnea
Authors: Braverman Max 
Published: June 2005

AbstractRemoving the sole hydranth from young slide grown colonies of the marine hydroid Podocoryne carnea stimulates an increase in the number of hydranths subsequently formed, compared to fed controls. If controls and experimentals are both starved, both show increased hydranth formation but the colonies without hydranths increase hydranth numbers sooner than do the starved controls. Hydranth formation is discontinuous under these experimental conditions as it is in unoperated growing colonies during the first 20 days of growth.When hydranths are removed from one half of each of a number of two week old colonies, stolon growth continues on the operated side at the same rate as on the unoperated side, indicating that nutriment is equitably distributed in the stolon system of the colony. Twice as many new hydranths are formed, however, on the operated side as on the control side. This experiment appears satisfactorily to control for the immediate starvation attendant upon hydranth removal, thus indicating that the location and therefore number of new hydranths in growing colonies of Podocoryne carnea is regulated by hydranths mediated feedback.Comparison of the age of stolon on which hydranths form with what would be expected were this distribution random, indicates a strong skew to stolon three and four days old. Whether this is an additional developmental stricture or a consequence of hydranth feedback can not now be determined.
Cytogenetic analysis of pig oocytes matured in vitro
Authors: McGaughey R. W. , Polge C. 
Published: June 2005

AbstractPrimary oocytes from the ovaries of prepubertal pigs were stimulated to undergo maturation by removing them from small follicles and incubating them in a defined culture medium for various periods of time. The cultured oocytes were air‐dried and their chromosomes examined for the stage of meiosis and for the presence of abnormalities. Of 107 oocytes recovered after 26–27.5 hours of culture 41% were at diakinesis‐metaphase I and 2% were at telophase I. Of 96 oocytes recovered after 36–37 hours of culture 46% were at diakinesis‐metaphase I while only 14% were at metaphase II. These observations suggest that the oocytes were delayed at diakinesis‐metaphase I, since it has been shown previously that at 36–37.25 hours after HCG injection only 23% of oocytes are at metaphase I and 45% are at metaphase II in vivo. When recovered after 42.5–55 hours of culture 128 of 232 oocytes (55%) had reached metaphase II.Of 56 cultured oocytes whose chromosomes were analysed at metaphase I, only one exhibited a chromosomal aberration (19 bivalents plus three fragments) and one oocyte contained 18 bivalents plus two monovalents.Of 123 oocytes analysed at anaphase I, telophase I and metaphase II, 33 (27%) exhibited such chromosomal abnormalities as heteroploidy, fragments, chromosomal bridges, tripolar spindles and lagging chromosomes. In addition 31% of 128 oocytes at metaphase II displayed degenerate chromosomes. Therefore, of 232 immature oocytes cultured for 42.5–55 hours only about 20% could be regarded as chromosomally normal, mature secondary oocytes.The delay at diakinesis‐metaphase I may be related to a failure of the supporting granulosa cells to supply some substance, possibly an energy source, required by the oocytes. It is suggested that during a delay at diakinesis‐metaphase I, the chromosomes of pig oocytes which failed to divide, may have become “sticky,” leading to the chromosomal aberrations observed at subsequent stages of meiosis.
Chromosome abnormalities of early rabbit embryos
Authors: Hofsaess F. R. , Meacham T. N. 
Published: June 2005

AbstractBlastocysts recovered six days after fertilization from five California and four Dutch‐Belted does were used to study the chromosome aberrations of early rabbit embryos. The nine does had a mean ovulation rate of 8.8 ± 0.7 (range 7 to 14). On the basis of corpora lutea counts, 95% of the embryos were recovered. Anomalies were found in nine of the 75 embryos recovered; there being two cases of hypoploidy (2n = 43), four cases of double hypoploidy (2n = 42), and three cases of mosaicism. In addition to the chromosomally abnormal embryos, three embryos could not be cultured successfully and appeared to be degenerating.
Neurosecretory activity and protease synthesis in relation to feeding in Melanoplus sanguinipes (Fab.)
Authors: Dogra G. S. , Gillott C. 
Published: June 2005

AbstractVirgin females of Melanoplus sanguinipes were starved for three days from emergence and then provided with food for various periods of time, ranging from five minutes to 72 hours. The temporal sequence of changes in neurosecretory activity, blood protein level and gut protease activity was investigated.The starved insect has a neurosecretory system loaded with stainable product. Feeding, however, promotes a massive release of this material within 20 to 40 minutes. A significant increase in the synthetic activity of the neurosecretory cells (measured as 3H‐L‐cystine incorporation) does not begin until about two hours after food intake. Five or six blood protein bands can be separated electrophoretically, of which 2 and 3 are always present in relatively high concentrations. They are also the most variable, the changes in total blood protein level being almost entirely a reflection of the changes in these two. the blood protein level being almost entirely a reflection of the changes in these two. The blood protein level decreases during the first 12 hours of feeding (from 1.94 to 1.07 g/100 ml) but increases rapidly over the next 60 hours to reach a value of almost 4 g/100 ml. Total protease activity (crop + midgut lumen + caeca) increases shortly after feeding has begun and after four hours is significantly greater than in the three‐day starved female. The activity continues to rise until it is about 2.5 × the starvation level after 72 hours.It is suggested that feeding stimulates the synthesis and release of neurosecretory material. The correlation between the rapid release of neurosecretion and early increase in protease activity is consistent with the hypothesis that the hormone acts directly upon the midgut epithelium stimulating protease synthesis. Furthermore the decrease in the level of blood protein for the first 12 hours after feeding could mean that it is being utilised in the production of digestive enzyme.
Ethanol induced notochord and spinal cord duplications in the embryo of the zebrafish, Brachydanio rerio
Authors: Laale Hans W. 
Published: June 2005

AbstractEmbryos of Brachydanio rerio, stage 10 (Hisaoka and Battle, '58) were exposed for 24 hours to graded concentrations of ethanol from 1 to 3%. Developmental abnormalities included defects of the eye, i.e., approximation, confluence and fusion of the optic cups mid‐ventrally; as well as duplications of notochord and spinal cord. Duplication of the spinal cord in the hind brain region has not been reported previously. The duplicatory effects are discussed and a mechanism of duplication by infolding roof plate material is proposed.
The stress response in the abundance of circulating leucocytes in the killifish, Fundulus heteroclitus III. The role of the adrenal cortex and a concluding discussion of the leucocyte‐stress syndrome
Authors: Pickford Grace E. , Srivastava Anil K. , Slicher Anna M. , Pang Peter K. T. 
Published: June 2005

AbstractThe response of intact Fundulus heteroclitus to intraperitoneal injections of ACTH at two hours post‐injection depends on the dose: leucopenia at low doses, leucocytosis at high doses. The two hour response to cortisol, at 5 μg/g, depends on the condition of the fish: leucocytosis in sexually mature or hypophysectomized fish, leucopenia in sexually regressed intact fish. At a physiological dose (0.025 μg/g) cortisol elicits a time sequence response in hypophysectomized recipients that is, initially, the reverse of that observed after coldshock: three minute leucocytosis, 15 minute leucopenia, and return to normal at 45 minutes. Leucocytosis emerges at two hours. Pretreatment with Metopirone for five to six days in the aquarium water is not well tolerated. Such treatment effectively blocks all phases of the cold‐shock response. Pretreatment for two days was tolerated and, in such fish, injection of epinephrine (1 μg/g) elicits both three minute and 30–60 minute leucopenia, but the leucocytic phases are blocked.A tentative interpretation of the cold‐shock sequence is proposed on the assumption that catecholamines (presumably epinephrine) are leucopenic and that cortisol is leucocytic.
Multiple forms of tyrosinase in rodents and lagomorphs with special reference to their genetic control in mice
Authors: Holstein Thomas J. , Quevedo Walter C. , Burnett Jean B. 
Published: June 2005

AbstractPolyacrylamide gel electropherograms of extracts of pigmented hair bulbs from rodents and lagomorphs indicate that tyrosinase exists in multiple molecular forms. Allelic substitutions at the a, b, c, d, and p color loci in mice reveal that the multiple forms of tyrosinase are subject to complex genetic influences. Depending upon genic constitution, a maximum of three electrophoretically‐separable forms of tyrosinase (T1 = 80,000 m. w.; T2 = 62,000 m. w.; T3 = 66,000 m. w.) can be visualized by incubation of the polyacrylamide gels in L‐DOPA. In certain genotypes of mice, T1, T2, and T3 are either greatly reduced in activity or absent. Urea, SDS, and EDTA fail to dissociate tyrosinase suggesting that the multiple molecular forms of tyrosinase are not simple aggregates of monomeric subunits stabilized by non‐covalent bonds.Tyrosinase corresponding in mobility to the T1 of mice is also found in hair bulb extracts from black rats, black rabbits, gerbils and golden Syrian hamsters. The T2 and T3 components are distinct in the black rat but are represented by a single “T2‐T3” band in the gerbil, hamster and rabbit. An additional T0 band is found in the black rat. Available evidence suggests that T1 of comparable electrophoretic mobility is widely distributed in mammals and may be an additional indication of an underlying broad homology of pigmentary genes. At present, it is not certain whether the multiple forms of tyrosinase are “true” isozymes or a single enzymic moiety bound to structural components of the melanosomal matrix.
Distribution and development of glutamine synthetase in the embryonic cerebral hemisphere
Authors: Piddington R. 
Published: June 2005

AbstractGlutamine synthetase (GS) activity is preferentially localized in a distinct cell mass, the ectostriatum, in cerebral hemispheres of late chick embryos. GS activities rise in the ectostriatum coincident with the growth of this prominent nucleus. GS development in the ectostriatum may be controlled by normal increases of 11β‐hydroxyl corticosteroids in late embryonic serum. It is clear in any case that GS activities in this area of the hemisphere are susceptible to precocious induction by these steroids in vitro. The significance of GS localization in the ectostriatum is discussed in terms of the possible normal roles for this enzyme in nervous tissue.
The fine structure of the retina in the newt, Triturus viridescens
Authors: Keefe J. Richard 
Published: June 2005

AbstractThe normal adult retina of the North American Urodele, Triturus viridescens, has been studied with the electron microscope. Three basic types of photoreceptors are observed: rods, possibly distinguishable as either red or green rods, single cones, and double cones. The photoreceptors differ from those reported in other amphibia in that: (1) none of photoreceptors contain an oil droplet; (2) all photoreceptors possess an enlarged paraboloid, and, (3) the double cones consist of two complete photoreceptors, a principal cone member and an accessory cone member. The two members are closely related to one another along the length of the inner segment through a clasping of the principal member within cytoplasmic expansions of the accessory member. The principal member inner segment bears strong resemblance to the single cone while the accessory member inner segment is rod‐like in nature.The sustentacular elements of this avascular retina display a diversity of scleral processes. The presence of specific collar‐like glial ensheathments of the photoreceptors at the external limiting membrane contrasts with the extensive interreceptor contacts between all photoreceptor elements throughout the outer nuclear layer. The synaptic bases are characterized by the presence of three types of specific contact sites: (1) interreceptor contacts among all receptor bases; (2) clusters of fine horizontal cell dendrites penetrate the receptor base and terminate in a superficial spray of typical axodendritic synapses; (3) prominent bipolar dendrites enter within the horizontal cell processes terminating in the typical retinal ribbon synapse.The significance of these observations are discussed with respect to the origin of the amphibian double cone, the metabolic support of the retinal, and the potential integration among the receptor cells.
Hormonal regulation of RNA synthesis by mouse mammary gland in vitro
Authors: El‐Darwish I. , Rivera E. M. 
Published: June 2005

AbstractExplants of mouse mammary glands were cultured for one to five days in chemically‐defined medium containing various combinations of insulin, corticosterone, and prolactin. The changes in RNA content and synthesis effected by the several hormone combinations were assessed after one, two, three, and five days of culture. Histological examination was also made to determine explant viability and secretory development.Insulin was responsible for the initial stimulation of RNA synthesis, but its activity fell after the first day. Prolactin and insulin effected maximal accumulation of RNA on the second day, but the influence of these two hormones also declined by the third day unless corticosterone was also present. The hormones in the sequential order in which they manifest their activity on mammary RNA thus appear to be: insulin, prolactin, corticosterone.The non‐parallel patterns of uridine incorporation and RNA accumulation suggest that the major fraction of hormone‐stimulated RNA is synthesized during the first two days and can be maintained by the appropriate hormonal milieu. The histological responses show that although insulin alone has an early effect on RNA synthesis, the subsequent secretory differentiation of the explants requires the further presence of prolactin and corticosterone.
In vitro culture of eggs and embryos of the viviparous paedogenetic gallmidge Heteropeza pygmaea
Authors: Went Dirk F. 
Published: June 2005

AbstractEggs and embryos of the viviparous paedogenetic gallmidge Heteropeza pygmaea can be cultivated in vitro throughout the entire period of egg follicle growth and embryonic development. During this process they increase in volume more than 100 times. The culture medium, consisting of hemolymph and fat body cells, is obtained from Z‐ray sterilized, full grown larvae of the same species. Embryonic development in this medium is essentially the same as it is in vivo.If the fat body cells of the culture medium have been damaged during their explanation, the embryos on the culture show vacuoles in their yolk syncytium after some time and do no develop further. If all fat body cells in a preparation stay intact, some of the embryos develop completely, whereas the others dissolve. Intact fat body lobes can not be used for in vitro culture, because they generally show degeneration which prevents embryonic development.The suitability of the culture method is discussed.