[Development trend of DDE-induced eggshell thinning of the white-tailed eagle, Haliaeëtus albicilla (L.) in East Germany].
Explore the source record for details and available documents.
Animals↗
SEARCH · Search PubMed
Results for “eggshell”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[Determination of the eggshell thickness. A simple method].
Explore the source record for details and available documents.
Animals↗
[Chemical and physical studies on the eggshell of 4 species of running birds (Struthioniformes)].
Explore the source record for details and available documents.
Animals↗
Resistance of the shell membrane and mineral layer to diffusion of oxygen and water in flexible-shelled eggs of the snapping turtle (Chelydra serpentina).
At oviposition, flexible eggshells of many turtles have an outer mineral layer and an inner membrane layer of approximately equal thickness. We measured conductances of both layers to H2O and O2 at various levels of eggshell hydration. Both the mineral layer of the eggshell and the shell membrane offer significant resistance to diffusion of water vapor and oxygen in eggshells of the snapping turtle, Chelydra serpentina. Conductance to water vapor increases in both the membrane and mineral layer with increasing hydration of the eggshell, but conductance to oxygen decreases under similar conditions. Removal of the mineral layer increases conductance to oxygen in moist and dry eggshells, but decreases conductance at intermediate levels of dehydration. Removal of the mineral layer consistently increases conductance to water vapor. The eggshell membrane accounts for 24-76% of overall resistance to diffusion of water vapor. These results suggest that bulk flow of H2O or physical changes in the shell may interact with diffusion to limit gas exchange through the turtle eggshell.
Animals↗
Eosinophil chemotactic factor release from neutrophils induced by stimulation with Schistosoma japonicum eggs.
The neutrophil is one of the sources of eosinophil chemotactic factor (ECF) in the presence of some stimulants. In the present study we showed that guinea-pig neutrophils could release ECF upon stimulation with Schistosoma japonicum eggs. ECF release from neutrophils began as early as 5 min after the stimulation and reached a peak at 20 min. When homogenate of the eggs was separated into a water-soluble fraction as soluble egg antigen (SEA) and a water-insoluble fraction (eggshell), both preparations possessed a potent neutrophil-stimulating activity to release ECF. The ECF release was dependent on the concentration of eggshells or SEA or on the number of neutrophils. The neutrophil-stimulating activity of eggshells was stable to heat, HCl, or pronase treatment but sensitive to NaOH treatment. When the eggs or eggshells were washed with acetone or Tween-20, they lost the neutrophil-stimulating activity to release ECF, indicating that the neutrophil-stimulating factor (NSF) possesses a lipid nature. The molecular weight of NSF extracted from the eggshells was estimated to be about 1000 Da by gel chromatography on Sephadex G25. The possible role of eggshells in the formation of eosinophil-rich granulomatous lesions in schistosomiasis japonica is discussed.
Animals↗
Calcium metabolism in olive ridley turtle eggs during embryonic development.
Analyses of calcium, magnesium, sulphur, potassium and phosphorus content of the eggshell, yolk-albumen and embryos of olive ridley turtle, Lepidochelys olivacea, have been carried out at various stages of embryonic development. Calcium is the major inorganic constituent in the egg (shell and yolk-albumen) and embryos. Other elements are present either in trace or in minute trace amounts. The egg contents (yolk and albumen) provide only 40% of the embryonic calcium requirement of the hatchling. The remaining 60% is provided by the eggshell. The eggshell also undergoes a similar reduction in its calcium content from laying to hatching. Elements other than calcium present in the yolk-albumen are sufficient for normal embryonic development. The movement of calcium from the eggshell to the embryo starts at about the 40th day of development at 29.5 degrees C. Birds, turtles and crocodiles use their eggshell as the secondary source of embryonic calcium requirement. This dependence on the eggshell varies in different groups which is highest in birds and lowest in crocodiles.
Albumins↗
Timing of the calcium intake and effect of calcium deficiency on behaviour and egg laying in captive great tits, Parus major.
The calcium demand of egg-laying birds is much higher than in other vertebrates during reproduction. We showed elsewhere that a low level of calcium availability can greatly affect the eggshell quality and reproduction of free-living passerines. However, there are few data on calcium demand and calcium intake in relation to egg laying and behaviour and egg-laying performance under conditions of calcium shortage in nondomesticated birds. We examined these aspects in an experiment with captive great tits, Parus major, on a diet deficient in calcium, with or without snail shells as an additional calcium source. More than 90% of the calcium intake for egg production took place during the egg-laying period. Females ingested about 1.7 times as much calcium as they deposited in eggshells. Removing the snail shells after the first egg resulted in eggshell defects and interruptions of laying after 1-3 d. Females without snail shells doubled their searching effort and started to burrow in the soil and to eat sand, small stones, and their own eggs. Most calcium was consumed in the evening, probably to supplement the calcium available from the medullary bone with an additional calcium source in the gut during eggshell formation. The results demonstrated that eggshell formation requires accurate timing of the calcium intake and that obtaining sufficient calcium is time-consuming, even in calcium-rich environments. These factors pertaining to calcium intake greatly affect the ability of birds to collect sufficient calcium for eggshell formation in calcium-poor areas.
Animals↗
Vital gas exchange and hatchability of turkey eggs at high altitude.
Conductance of turkey eggshells was observed to be significantly (P less than .01) greater at 2000 than at 200 m elevation. It was concluded that the increased conductance may have been due to the Chapman-Enskog relation. Eggshells of nonhatching eggs from the high altitude were examined, and it was determined that despite the increased conductance rate, eggshells with significantly (P less than .05) less functional pore area hatched poorly in both oxygenated and nonoxygenated environments. When oxygen was not supplemented to the incubators at high altitudes, eggshells required significantly (P less than .01) fewer pore concentrations to allow embryos to survive to late stages of embryonic development than eggs in oxygen supplemented environments. However, greater pore concentrations on the air space were required in both environments to complete hatching. Cuticle removal from eggshells incubated in oxygen supplemented incubators at high altitudes significantly (P less than .05) reduced late embryonic mortality. It was concluded that eggshell cuticle removal may be more advantageous to hatchability at high altitude than oxygen supplementation.
Altitude↗
The hatching mechanism in Atlantic halibut (Hippoglossus hippoglossus).
In general fish larvae emerge from the protective egg after secreting a hatching enzyme (HE) from diffusely located hatching gland cells (HGCs). This proteolytic enzyme is distributed over the entire inner part of the eggshell (zona radiata). In a marine flatfish halibut, (Hippoglossus hippoglossus), we have found a more specialized hatching process. A strategic location of the HGCs in a narrow belt on the anterior part of the yolk sac leads to restricted degradation of the eggshell resulting in cleavage of the eggshell into two distinct rigid parts. This hatching process--termed "rim-hatching"--results in an empty eggshell with a lid approximately 1/4 the size of the bottom shell. During the hatching process the yolk sac is reshaped. The posterior part of the yolk sac contracts and the yolk mass is squeezed forward before hatching. This mechanism ensures close contact between the HGCs and the eggshell during the release of the hatching enzyme, which is a prerequisite for restricted degradation of the eggshell.
Animals↗
Histology and functional morphology of the female reproductive tract of the tortoise Gopherus polyphemus.
The oviducts of 25 tortoises (Gopherus polyphemus) were examined by using histology and scanning electron microscopy to determine oviductal functional morphology. Oviductal formation of albumen and eggshell was of particular interest. The oviduct is composed of 5 morphologically distinct regions; infundibulum, uterine tube, isthmus, uterus, and vagina. The epithelium consists of ciliated cells and microvillous secretory cells throughout the oviduct, whereas bleb secretory cells are unique to the infundibulum. The epithelium and endometrial glands of the uterine tube histologically resemble those of the avian magnum which produce egg albumen and may be functionally homologous. The isthmus is a short, nonglandular region of the oviduct and appears to contribute little to either albumen or eggshell formation. The uterus retains the eggs until oviposition and may form both the fibrous and calcareous eggshell. The endometrial glands are histologically similar to the endometrial glands of the isthmus of birds, which are known to secrete the fibers of the eggshell. These glands hypertrophy during vitellogenesis but become depleted during gravidity. The uterine epithelium may supply "plumping water" to the egg albumen as well as transport calcium ions for eggshell formation. The vagina is extremely muscular and serves as a sphincter to retain the eggs until oviposition. Sperm are found within the oviductal lumen and endometrial glands from the posterior tube to the anterior uterus throughout the reproductive cycle. This indicates sperm storage within the female tract, although the viability and reproductive significance of these sperm are unknown.
Animals↗
In vitro hatching of the tapeworm Moniezia expansa (Cestoda: Anoplocephalidae) and some properties of the egg membranes.
In vitro studies revealed that the hatching of oncospheres of Moniezia expansa requires the mechanical breakage of the eggshell and subshell membrane and enzymic digestion of the pyriform apparatus. Removal of the outer two egg membranes elicits the activation of most oncospheres. Between pH 5.0-7.8, there is no significant difference in numbers of oncospheres activated by eggshell removal and the addition of sodium bicarbonate has no effect. Solutions of more extreme pH values (2.0 and 10.0) are harmful and render oncospheres immobile. The subshell membrane forms a barrier to the passage of water in an osmotic gradient and to several molecular and ionic substances. Between the eggshell and subshell membrane is a layer of droplets which have a strong affinity for Sudan stains and which are partially removed by lipase. The eggshell is resistant to a variety of proteolytic enzymes, amylases and lipase. The pyriform apparatus is digested by chymotrypsin and pepsin, though not by trypsin. Both eggshell and pyriform apparatus are dissolved by solutions of sodium sulphide and sodium hypochlorite, indicating that their structures are stabilized by disulphide bonds and other covalent linkages.
Animals↗
The effect of avian uterine fluid on the growth behavior of calcite crystals.
Eggshell formation takes place on the eggshell membrane in an acellular medium, the uterine fluid that contains the inorganic minerals and precursors of the organic matrix. The high degree of eggshell structure could be due to an interaction between calcium carbonate and the organic matrix. The aim of this study was to demonstrate such an interaction by measuring the effect in vitro of uterine fluid collected at various phases of shell formation on precipitation kinetics, size, and morphology of calcite crystals. The SDS-PAGE profiles of the organic constituents differed between the different phases of eggshell formation. The predominant constituents were ovalbumin and ovotransferrin at the initial phase and lysozyme, ovocleidin-17, ovocalyxin-32, 36- and 21-kDa bands, and ovocleidin-116 at the growth phase. These proteins were numerous in the terminal phase and showed an increased staining of the 32- and 66-kDa bands and appearance of very low molecular weight bands. The precipitation lag time was shortened in proportion to the protein concentration at the initial stage. The effect was observed with a lower magnitude in the presence of constituents of growth and terminal phases. Crystal size was smaller in the presence of constituents from the three stages compared with the control. Components from the initial phase induced the formation of twinned crystals and of rounded corners in the rhombohedric crystals. The presence of components from the growth and terminal phases strongly modified the morphology of the calcite crystals. The majority of the corners became rough and developed curved faces. These observations confirm the interaction of the uterine fluid with calcite and its contribution to eggshell structure.
Animals↗
Fluorosis in the laying hen.
One hundred fifty Single Comb White Leghorn hens of two strains previously selected for either high eggshell strength (HES strain) or low eggshell strength (LES strain) were treated for 8 weeks with sodium fluoride added to a practical-type corn-soybean meal basal diet at 0, 300, 600, 900, or 1200 ppm. The HES strain was found to be more sensitive to fluorosis than the LES strain. High levels of dietary fluoride produced greater decreases in feed consumption, egg production, eggshell breaking strength, eggshell weight, and eggshell thickness in the HES strain than in the LES strain, despite the fact that the absolute intake of fluoride was greatest in the LES strain. Fluoride treatment significantly increased bone magnesium content in both strains and plasma phosphorus in the HES strain but did not significantly affect bone breaking strength or the concentrations of total calcium, ionized calcium, or magnesium in plasma of either strain. High fluoride treatment (1200 ppm) reduced the growth of HES progeny after 8 weeks of treatment of the hens, but LES progeny were not affected. These results suggest that the decreased sensitivity of the LES strain to fluoride may relate to its relatively greater (ca. 14%) volume of bone in which most absorbed fluoride is deposited.
Animals↗
Influence of diet-mediated maternal thyroid alterations on functional properties of turkey eggs.
Maternal thyroid status was altered by means of diet to determine its effect on functional properties of turkey eggshells. Hens were fed a control diet (CON), the CON diet containing .5 ppm triiodothyronine (T3), the CON diet containing 2.1 ppm iodine as potassium iodide (KI) or the CON diet containing .1% thiouracil (THIO). Feeding T3 decreased plasma thyroxine but elevated plasma T3 concentrations compared to CON. The KI diet had no effect on plasma thyroid hormone concentrations, but feeding THIO depressed plasma thyroxine with no effect on T3, resulting in an elevated ratio of the two hormones compared to the CON ratio. Feeding KI decreased egg volume and T3 increased egg density compared to CON, but no effects on egg weight, surface area, width, or length were noted. Dietary T3 depressed eggshell water vapor conductance compared to CON. Dietary iodine resulted in thinner eggshells with fewer pores than the CON, whereas THIO caused significantly more pores in eggshells than CON but had no effects on shell thickness. Dietary KI had no effects on maternal plasma thyroid hormone concentrations, suggesting that the effects were due to iodine availability rather than to thyroid hormones. It is concluded that the availability of iodine to turkey breeder hens may influence eggshell characteristics.
Animals↗
Research note: responses of laying hens on saline drinking water to dietary supplementation with various zinc compounds.
Production variables, eggshell defects, eggshell quality, the concentration of calcium-binding protein (CaBP), and the activity of carbonic anhydrase (CA) in the shell gland mucosa were determined in hens receiving town water (10 mg Na/L), or town water supplemented with 2 g NaCl/L (796 mg Na/L). Five treatments were examined. Control hens received town water and a proprietary layer mash containing .17% Na. The remaining four treatments received the water containing NaCl (2 g/L). Hens of Treatment 2 were fed the proprietary layer mash and those of Treatments 3, 4, and 5 received, respectively, the layer mash containing supplements of Zn-methionine (Zinpro-200; .5 g/kg), Zn sulfate (ZnSO4.7H2O; .46 g/kg), or chelated Zn-EDTA (.54 g/kg) to supply the same concentration of Zn (.1 g/kg). The treatments were applied for 6 wk. Hens receiving the saline drinking water without any dietary Zn supplement produced significantly (P < .05) more eggs with shell defects than hens receiving the town water. This increase in the incidence of eggshell defects was associated with significant reductions in eggshell breaking strength, the concentration of CaBP, and the activity of CA. Supplementing the saline drinking water with any of the three Zn compounds significantly reduced the incidence of eggshell defects and in some cases improved shell breaking strength, the concentration of CaBP, and the activity of CA.
Animal Feed↗
Salmonella contamination in commercial eggs and an egg production facility.
Egg samples were collected from various stages of an egg processing operation and from the attached production facility. Salmonella was isolated from 72.0% of all samples collected from the laying house environment. Recovery of Salmonella from flush water, ventilation fan, egg belt, and egg collector samples were (positive samples/total samples collected): 2/2, 4/4, 16/22, and 14/22, respectively. Salmonella was found on 7 of the 90 eggshells sampled before processing and 1 of 90 eggshells sampled after processing, but Salmonella was not found in the 180 eggs analyzed for internal contamination following processing. The one eggshell found positive for Salmonella following processing was detected when the pH of wash water samples was lowest (10.19). The 60 isolates from production facilities included the following Salmonella serotypes: S. agona, S. typhimurium, S. infantis, S. derby, S. heidelberg, S. california, S. montevideo, S. mbandaka, and untypable. The 22 isolates obtained from eggshells prior to processing were serotyped as S. heidelberg and S. montevideo. All five isolates obtained from eggshells after processing were serotyped as S. heidelberg. These data suggest that although the shells of about 1% of commercial eggs are contaminated with Salmonella, contamination of the internal contents of eggs with Salmonella is a rare event.
Animals↗
Regulation of extraembryonic calcium mobilization by the developing chick embryo.
During development, the chick embryo mobilizes the calcium it needs from two extraembryonic sources, first the yolk and then the eggshell. Since previous studies have strongly suggested that vitamins D and K may regulate chick embryonic calcium metabolism, we have examined here how these vitamins might be involved in regulating the calcium mobilization processes. We used as our experimental system chick embryos which were maintained in long-term in vitro culture in the absence of the eggshell. Our results showed that exogenous vitamin D3, in the form of the active 1,25-dihydroxylated metabolite, was hypercalcaemic in both control embryos and the calcium-deficient, shell-less embryos. Since the eggshell was absent in the latter, the vitamin D-induced hypercalcaemia must involve mobilization of calcium from the yolk and, or, the embryonic skeleton. The latter was unlikely since concomitant hyperphosphataemia was not observed. By radiolabelling the yolk with 45Ca2+ and subsequently monitoring its distribution, we showed that vitamin D3 stimulated yolk calcium mobilization. However, exogenous vitamin D3 did not appear to influence the calcium uptake activity of the chorioallantoic membrane (CAM), the tissue responsible for translocating eggshell calcium. On the other hand, when embryos were rendered vitamin K deficient by the administration of its antagonist, Warfarin, CAM calcium activity was significantly depressed, an effect which was remedied by vitamin K supplementation. We conclude that, during normal chick embryonic development, vitamin D is primarily involved in regulating yolk calcium mobilization whereas vitamin K is required for eggshell calcium translocation by the CAM.
Allantois↗
Effects of PCBs, DDT, and mercury compounds in chickens and Japanese quail.
In well-controlled experiments using white leghorn chickens and Japanese quail, dietary polychlorinated biphenyls (PCBs), DDT and related compounds produced no detrimental effects on eggshell quality. A drastic reduction in hatchability of chicks occurred with 10-20 ppm PCBs, but no detrimental effects on eggshell quality, egg production or hatchability were found with 0.5 and 1.0 ppm PCBs, or DDT up to 100 ppm. Dietary PCBs potentiated a vitamin E-selenium deficiency in the chick, increased exudative diathesis, and decreased plasma glutathione peroxidase levels. Dietary PCBs induced hepatic microsomal benzopyrine hydroxylase. Dietary levles of 100 or 200 ppm inorganic mercury as HgSO4 or HgCl2 had little effect on egg production, hatchability, shell quality, morbidity and mortality. Methylmercury chloride, however, at levels providing 10 or 20 mg Hg/kg of diet, severely affected all of these parameters. Even though the present experiments demonstrate that neither DDT nor PCBs has any effect on eggshell quality in chickens and Japanese quail, they may cause thinning of eggshells in other species. Controlled experiments are lacking. Eagles, ospreys and pelicans all consume fish which in many areas of the world are known to contain methyl mercury. The thinning of eggshells in the species in the wild may have been due, at least in part, to environmental contamination with methylmercury rather than DDT, DDE or PCBs, as has been claimed.
Animals↗