摘要:

AbstractPreincubation of sperm in medium for three hours before mixing with ova increased the number of ova fertilized after one hour, thus indicating that sperm maturation occurs in vitro. The presence of cumulus cells increased the proportion of ova fertilized as observed at two and at three hours after the addition of sperm. However, no difference in the proportion of ova fertilized after one hour of incubation was observed using fresh epididymal sperm and ova with or without cumulus cells. No additive effect of cumulus cells and sperm preincubation on fertilization was observed. Sperm preincubation for three hours in the presence of ova either with or without cumulus cells resulted in fertilization similar to that achieved by sperm preincubated in medium alone.

ISSN:0022-104X    

DOI:10.1002/jez.1401880202

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe extraordinary resistance to disruption shown by the eutherian sperm nucleus is associated with a significant complement of ‐S‐S‐ crosslinks within the chromatin. The present light and electron microscopic study, in which the spermatozoa of many vertebrates and some invertebrates were exposed to SDS with or without dithiothreitol, demonstrates that the extreme degree of disulfide bonding in the sperm chromatin of eutherian mammals is highly unusual in a comparative sense. In no other species did the sperm nucleus display a resistance to disruption comparable to that in eutherians; on the contrary, in most groups including prototherian and metatherian mammals, such crosslinks are absent or relatively sparse, the greatest degree of crosslinking outside the eutheria being seen in octopus and skate.The suggestion is advanced that the unusually thiol‐rich protamines have evolved as a structural adaptation which, through crosslinking, endows the sperm head with a rigidity of possible importance in the penetration phase of fertilization. This seems likely because (1) any degree of ‐S‐S‐ determined stability present or inducible in sperm chromatin often appears more intense in or is confined to the anterior region of the nucleus (e.g., newt, snail, turtle and immature eutherian spermatozoa); (2) the zona pellucida, which the fertilizing sperm must penetrate, is an unusually thick, compact and resilient coat in the eutherian ovum in particular; and (3) the occasional observation of a sperm nucleus buckled within the pathway of its penetration into the rabbit zona pellucida suggests that in eutheria this tough vestment presents a relatively rigid barrier to the sperm head.Its apical location suggests a similar structural role for the ‐S‐S‐ stabilised perinuclear projection, or “perforatorium” around the leading border of the sperm nucleus in eutherians as well as in some non‐eutherian species, such as

ISSN:0022-104X    

DOI:10.1002/jez.1401880203

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

年代:1974

数据来源: WILEY

摘要:

AbstractTwelve sugars in 0.5Msolution in water and also in 0.5Msolution in 0.5Msucrose were fed to newly emerged, caged honey bee workers. After 11 to 27 hours, the sugars of ice water extracts of degutted thoraces were promptly analyzed by thin‐layer chromatography.Unlike published values for sugars in the hemolymph from healthy bees, trehalose was the predominant sugar in the thorax. Lesser amounts of glucose and only traces of fructose were found. Trisaccharides were found in the thorax after they were fed to bees.Progress was made toward determining which nonsustentative sugars are toxic and which are not accepted. Galactosides seem toxicper seand not to be progenitors of toxic galactose. Galactosides and mannose gave no buildup of a particular sugar to indicate metabolic blockage. Starved bees and moribund bees with empty crops contained glucose but no trehalose. Analysis of thoracic sugars has potential value in diagnosis of bee poisonin

ISSN:0022-104X    

DOI:10.1002/jez.1401880204

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

年代:1974

数据来源: WILEY

摘要:

AbstractGemmulated, female sponge was collected from nature on 10 November 1971 and then stored in the laboratory at 3°C in the dark. Pieces of this sponge were set out in the pond of origin on 29 May, 6 July, 10 August, and 14 September 1972 and on 16 May 1973. Oocyte production was observed in all sponges developing from the hatched gemmules about one week after implantation. The production of young oocytes ceased three or four weeks following implantation except in the sponges implanted on 14 September 1972, which continued to produce oocytes up to 6 November. This extended period of oocyte production was associated with and may be due to low water temperatures.The study shows that oocyte production does not require an environmental stimulus specific to a particular time of year, for oocytes differentiated under conditions of increasing as well as decreasing water temperatures and day lengths. The control of oocyte production is probably endogenous and associated with gemmule hatching. The possible nature and the adaptive significance of this control mechanism are discussed.Oocytes produced in sponges implanted after the normal sexual period in the pond were not fertilized. Such oocytes go through the normal growth sequence up to the end of the “grand accroissement” phase. Then they degenerate, ultimately releasing their stored yolk bodies into the mesenchyme.All evidence indicates that this population of the species is dioec

ISSN:0022-104X    

DOI:10.1002/jez.1401880205

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

年代:1974

数据来源: WILEY

摘要:

AbstractFertilization in the hydrozoanCampanularia flexuosais internal and may be considered to include events in the female reproductive organ (the gonangium) prior to zygote formation. Prior to fertilization the spermatozoan must move through the female gonangium to the site of sperm‐egg fusion. The female gonangium contains sheets of epithelial cells which distally line the entrance and proximally form passageways that lead to and surround the eggs. After chemotactic attraction to the gonangium aperture, the spermatozoa adhere to the epithelial cells by their outer surfaces, but they continue to move downward along the distal gonangium epithelia and through the passageways to the germinal vesicle area of the egg. As the spermatozoa move deeper into the gonangium the 640–700 Å membrane‐bounded (“pro‐acrosomal”) vesicles of the sperm progressively decrease in number. By the time the spermatozoa reach the egg, 88% of the vesicles have been lost. It is possible that the contents of the vesicles play a role in the control of spermatozoan‐epithelial cell adhesion or that they serve, in some way, to permit sperm penetration to the egg surface. Alternatively, their loss may be a morphological indication of the capacitation‐like interaction between the sperm and normal female gonangium epithelial cells which is required for fertilization inCampa

ISSN:0022-104X    

DOI:10.1002/jez.1401880206

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

年代:1974

数据来源: WILEY

摘要:

AbstractInduction of supernumerary limbs in Bufo tadpoles was achieved by transplanting the transverse neural fold with adjoining tissue from neurulae into tail bud stage embryos. The graft differentiated into brain, eyes, noses and mouthparts. Induced limb rudiments were associated with either noses or mouthparts. The author rejects the suggestion made by Perri that the induction is due to release of products of cytolysis from the graft and suggests that limb induction is due to a disorganization or reduction of the subepidermal basement membrane (layer of collagen fibres) by certain grafts, and that as a result the potentially limb forming flank mesenchyme is allowed to interact with the epidermis — a precondition for limb development. In support of this view the author presents electronmicrographs in which it is shown that at the edge of the nostril, and on the mouthparts (lips, oral papillae), the basal membrane is attenuated and disorganised, allowing processes of mesenchyme cells to penetrate through the layer of collagen fibres and reach the inner surface of the epidermi

ISSN:0022-104X    

DOI:10.1002/jez.1401880207

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe influence of the site of semen deposition on the rate of sperm capacitation was studied in 36 oestrous gilts in which ovulation had been induced at a precise time. Aliquots of semen were instilled into the proximal uterine horn on one side of the tract and into the isthmus of the contralateral Fallopian tube in 24 animals. Eggs were recovered in vivo, and examined by phase‐contrast microscopy for the number of spermatozoa associated with the zona pellucida and the stage of fertilization.A total of 420 eggs was examined. The mean number of spermatozoa per egg increased from 3.3 at four hours after uterine insemination to 27.9 at six hours, compared with 0.6 to 6.3 at corresponding intervals after tubal insemination (p<0.05). The mean proportion of fertilized eggs increased from 54.3% at four hours to 95.9% at six hours after uterine insemination, compared with 0.0 to 51.0% at these intervals after tubal insemination (p<0.001). The temporal advantage accruing from uterine insemination was also seen in the developmental stages of the penetrated eggs. In a further six animals in which seminal plasma was introduced into the isthmus at the time of uterine insemination, fertilization was retarded by approximately two hours, although when a similar volume of physiological medium was introduced into the isthmus as a control, no such delay was observed.The advantage of uterine over tubal insemination was attributed to a synergistic effect of the uterus and Fallopian tubes on those spermatozoa that penetrated the eggs. The nature of the membrane‐related changes in the spermatozoon initiated during passage through the uterus and utero‐tubal junction that facilitate rapid capacitation remains unknown, but is thought to involve modification or removal of seminal plasma constituents from the sperm surface. It was inferred that seminal plasma does not enter the Fallopian tubes of oestrous pigs in significant amounts after m

ISSN:0022-104X    

DOI:10.1002/jez.1401880208

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

年代:1974

数据来源: WILEY

摘要:

AbstractSome comparative biochemical studies on the hemoglobin from the clouded tiger salamander, Ambystoma tigrinum nebulosum, before and after metamorphosis indicate (1) there is no hemoglobin change with metamorphosis; (2) both hemoglobins show three major fractions (Fractions I, II, III) in ion exchange chromatography and two bands in gel electrophoresis; (3) these fractions possess identical chemical properties except for their electrophoretic mobilities, and peptide maps; (4) Under our experimental conditions, Fraction II can be formed by the appropriate recombination of subunits present in equilibrium with Fractions I and II.

ISSN:0022-104X    

DOI:10.1002/jez.1401880209

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe subcellular distribution of the first three enzymes in the ommochrome eye pigment pathway were studied by means of differential centrifugation. Tryptophan pyrrolase and kynurenine formamidase are found in the soluble fraction of the homogenate. A relatively small amount of tryptophan pyrrolase, 10 to 15% of the total, is sedimentable. The head region of pupae contains approximately 15% of the total activity of the animal. The subcellular distribution of the activity of the head is not appreciably different from the distribution of activity in the rest of the animal. Therefore no evidence suggests that the enzyme exists in a particulate form specifically in the head. Kynurenine hydroxylase is judged to be a mitochondrial enzyme on the basis of its co‐sedimentation with particles containing cytochrome oxidase and by the demonstration of mitochondria in the sedimented fractions containing kynurenine hydroxylase activity. Kynurenine hydroxylase was judged not to be present in pigment granules since developmental and genetic changes in pigment granule morphology do not affect the sedimentation of kynurenine hydroxylase containing particles. These results on the three enzymes lead us to conclude that they are not organized into a single multi‐enzyme complex as has been previously suggested. A consideration of the six ommochrome deficient mutants indicates that four of these can be explained by existing data. A hypothesis which does not involve enzyme complexes is presented to account for the remaining

ISSN:0022-104X    

DOI:10.1002/jez.1401880210

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

年代:1974

数据来源: WILEY

摘要:

AbstractElectron micrographs of the labellar chemosensory hairs of the mosquito show that these sensilla have either three or four dendrites extending the length of the shaft. At the tip of each hair is a circular pore. The dendrites are enclosed within a scolopoid structure. At the distal end of the dendrites the microtubules are arranged in a random manner, but, in the proximal area, they are grouped into nine pairs. Near the base the pairs assume a spiral pattern giving rise to a three‐compartmented structure which forms the root proper.Action potentials were recorded from the hairs, using NaCl at concentrations of 0.002Mto 1.0M. Four different spikes were recognized — water and three salt. The salt spikes were labeled Types a, b, and c. None of these is identical with the L spike from the blowfly. All four spikes were recorded from some hairs which were certainly those with four dendrites.Behavioral studies demonstrated that the rejection threshold of NaCl for labellar hairs was 0.28M. This coincides with a rapid increase in the electrical activity of the Type c salt cell. From behavioral and electrophysiological evidence it was concluded that acceptance byCulisetaof NaCl in aqueous solution is the result of activity of the water receptor plus input from the salt receptors Types a and b, and that rejection results from activity of the Type c salt c

ISSN:0022-104X    

DOI:10.1002/jez.1401880211

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

年代:1974

数据来源: WILEY