A study of the egg shells of the Sphenisciformes

Tyler, C.

doi:10.1111/j.1469-7998.1965.tb01873.x

Cited by 42 publications

(24 citation statements)

References 11 publications

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“…A pore provides direct connection between the outside environment and the spaces between the cones. Tyler (1964bTyler ( , 1965Tyler ( , 1966bTyler ( , 1969 and Tyler & Simkiss (1959b) have studied pore structure in different types of birds by the technique of making casts (Tyler 1956) and shown that different bird groups have pore channels of different shape and structure.…”

Section: Poresmentioning

confidence: 99%

The Ultrastructure of the Avian Eggshell

Becking¹

1975

Ibis

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Most vectors of arthropod-borne diseases produce large eggs with hard and opaque eggshells. In several species, it is still not possible to induce molecular perturbations to the embryo by delivery of molecules using microinjections or eggshell permeabilization without losing embryo viability, which impairs basic studies regarding development and population control. Here we tested the properties and permeability of the eggshell of R. prolixus, a Cha-gas disease vector, with the aim to deliver pharmacological inhibitors to the egg cytoplasm and allow controlled molecular changes to the embryo. Using field emission scanning and transmission electron microscopy we found that R. prolixus egg is coated by three main layers: exochorion, vitelline layer and the plasma membrane, and that the pores that allow gas exchange (aeropiles) have an average diameter of 10 μm and are found in the rim of the operculum at the anterior pole of the egg. We tested if different solvents could permeate through the aeropiles and reach the egg cytoplasm/embryo and found that immersions of the eggs in ethanol lead to its prompt penetration through the aeropiles. A single five minute immersion of the eggs/embryos in pharmacological inhibitors, such as azide, cyanide and cycloheximide, solubilized in ethanol resulted in impairment of embryogenesis in a dose dependent manner and DAPI-ethanol solutions were also able to label the embryo cells, showing that ethanol penetration was able to deliver those molecules to the embryo cells. Multiple immersions of the embryo in the same solutions increased the effect and tests using bafilomycin A1 and Pepstatin A, known inhibitors of the yolk proteolysis, were also able to impair embryogenesis and the yolk protein degradation. Additionally, we found that ethanol pre-treatments of the egg make the aeropiles more permeable to aqueous solutions, so drugs diluted in water can be carried after the eggs are pre-treated with ethanol. Thus, we found that delivery of pharmacological inhibitors to the embryo of R. prolixus can be performed simply by submersing the fertilized eggs in ethanol with no need for additional methods such as microinjections or electroporation. We discuss the potential importance of this methodology to the study of this vector developmental biology and population control.

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Section: Poresmentioning

confidence: 99%

The Ultrastructure of the Avian Eggshell

Becking¹

1975

Ibis

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“…In the same paper, Nathusius suggested that the Sphenisciformes are close to the Pelecaniformes, but this C . T Y L E R is not true since Tyler (1965) has shown structures in the Sphenisciformes which do not appear in the Pelecaniformes at present being studied.…”

Section: Shell Structure: Cuticle and Covermentioning

confidence: 85%

“…Underneath the cover the true shell is pure white. Small pimples, like those seen on Sphenisciformes egg shells (Tyler, 1965), or flatter blisters are observed on some eggs, in others the outer surface of the cover is scratched or the cover has been partly torn off. In shells where the cover was thick, it has often cracked giving a crazy paving effect.…”

Section: General Structurementioning

confidence: 94%

“…Polarized light and other studies show that the cover consists of organic matter in which are embedded small crystals of calcite. The cover appears generally bright in polarized light because in any one position there will always be a large number of small shell structure between these two orders since the typical cover of the Sphenisciformes (Tyler, 1965) is completely absent in the Procellariiformes.…”

Section: Shell Structure: Cuticle and Covermentioning

confidence: 99%

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A study of the egg shells of the Gaviiformes, Procellariiformes, Podicipitiformes and Pelecaniformes

Tyler

1969

Journal of Zoology

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Egg shells of the Gaviiformes, Procellariiformes, Podicipitiformes and Pelecaniformes have been studied using general inspection, chemical analysis, histological and plastic embedding techniques. In all four orders there is a true shell consisting of large crystals having their origin at the surface of the membrane. In the Gaviiformes and Procellariiformes, the true shell is then covered with a cuticle, while in the Podicipitiformes and Pelecaniformes (except for the Phaethontidae) there is a calcareous cover over the true shell. Histological studies showed no major difference in the organic matrix of the true shell as between the four orders. Pore channels are all single and, in those egg shells which have a cover, these channels do not penetrate the cover. Considerable pigmentation is present in the Gaviiformes egg shells and also in the Phaethontidae, and pigment spots occur not only on the surface but also in the body of the shell. Studies of the apparent density of the true shells and the covers showed interesting differences. The taxonomic aspect of the results is discussed.

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“…In the lab all eggshells were soaked and boiled in distilled water to remove the membranes more easily (Tyler 1965). We selected ten shell fragments from each egg at random and measured their thickness with electronic calipers to the nearest 0.01 mm.…”

Section: Methodsmentioning

confidence: 99%

Differences in egg size, shell thickness, pore density, pore diameter and water vapour conductance between first and second eggs of Snares Penguins Eudyptes robustus and their influence on hatching asynchrony

Massaro

Davis

2005

Ibis

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Brood reduction in birds is frequently induced by hatching asynchrony. Crested penguins (genus Eudyptes) are obligate brood reducers, but in contrast to most other birds, first‐laid eggs are considerably smaller in size than second‐laid eggs; furthermore, first‐laid eggs hatch after their siblings. The mechanisms underlying this reversal in size and hatching order remain unclear. In this study, we tested whether the second‐laid eggs of Snares Penguins Eudyptes robustus have a higher eggshell porosity allowing them to maintain a higher metabolic rate throughout incubation and to hatch before their first‐laid siblings. We investigated differences in egg size, shell thickness, pore density, pore diameter and water vapour conductance between first and second eggs within clutches and examined the influence of these shell characteristics on hatching asynchrony. First‐laid eggs of Snares Penguins were approximately 78% of the size of the larger second eggs. Second‐laid eggs had considerably thicker shells and more pores per cm2 than first eggs, whereas pore diameter did not differ between eggs. Water vapour conductance was greater in second‐ (16.8 mg/day/torr) than in first‐laid eggs (14.9 mg/day/torr). The difference in water vapour conductance between first‐ and second‐laid eggs within clutches was related to hatching patterns. In nests where second eggs hatched before first‐laid eggs, second eggs had a considerably greater water conductance than their sibling, whereas in nests where both eggs hatched on the same day, the difference in water conductance between eggs was very small, and in a few nests where small first eggs hatched before their larger sibling, they had a greater water conductance than their larger second‐laid nestmate. Surprisingly few studies have investigated differences in shell characteristics between eggs within clutches and associated effects on hatching asynchrony. This study has demonstrated that such differences exist between eggs within clutches and that they can influence hatching patterns.

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A study of the egg shells of the Sphenisciformes

Cited by 42 publications

References 11 publications

The Ultrastructure of the Avian Eggshell

The Ultrastructure of the Avian Eggshell

A study of the egg shells of the Gaviiformes, Procellariiformes, Podicipitiformes and Pelecaniformes

Differences in egg size, shell thickness, pore density, pore diameter and water vapour conductance between first and second eggs of Snares Penguins Eudyptes robustus and their influence on hatching asynchrony

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