Memoirs: The Formation and Structure of the Chorion of the Egg in an Hemipteran, Rhodnius prolixus

1946 ◽  
Vol s2-87 (348) ◽  
pp. 393-439
Author(s):  
J. W. BEAMENT
Keyword(s):  
Average Diameter ◽  
Water Soluble ◽  
Follicle Cells ◽  
Protein Layer ◽  
Secretory Products ◽  
Large Water ◽  
Protein Components ◽  
Egg Shell ◽  
Pore Canals ◽  
Strong Acids

The main regions of the Ehodnius prolixus egg-shell have been defined; a concise definition has been obtained for the term ‘chorion’. The formation and structure of the unspecialized chorion has been followed from the time of differentiation of the follicle cells, up to the completion of the shell, and an assessment made of the chemistry and permeability of each component shell layer. The follicle cells are binucleate; changes in morphology and histology prior to secretion of the shell are outlined. The secretory products of the follicle cells fall naturally into an endochorion and an exochorion; the endochorion consists of five modifications of a proteinaceous substance. They are, in order of secretion: 1. The Inner Polyphenol Layer, which consists of a series of tanned granules of average diameter 2µ, containing large quantities of polyphenols. The layer is discontinuous and has no effect on permeability. 2. The Resistant Protein Layer, a tanned and possibly vulcanized layer of protein, 1 to 2µ, thick, containing diffuse polyphenols. It is resistant to strong acids and bases, and permeable to water, ions, and large water-soluble molecules. 3. The Outer Polyphenol Layer, which is similar to the inner layer, but has more minute granules. 4. The Amber Layer.--This is the only coloured layer of the shell, and is less than 0-1µthick. It consists of tanned protein to which oil is added after secretion. It is therefore a lipidized protein, which is excessively resistant to acids and alkalies, and permeable to oils and oil-soluble material and to small ions and water. 5. The Soft Protein Layer.--This is a thick laminated layer some 8µ. thick, similar to, but less resistant than, the resistant protein layer. It contains polyphenols and tyrosine. The layer is freely permeable to water-soluble substances. Throughout the secretion of the endochorion, the follicle cells stain deeply and appear to be filled with the protein components of the shell. The exochorion consists of two layers of the lipoprotein ‘chorionin’. 6. The Soft Exochorion Layer is a lipoprotein which is soluble in potash but not in strong acids; the layer is permeable to lipoid solvents and to water and small ions, but not to larger particles. It is 8µ thick at its maximum thickness, but contains follicular pits which, during secretion, are filled by long processes from the follicle cells. 7. The Eesistant Exochorion Layer is a more resistant form of chorionin. It lines the pits and covers the surface of the shell, giving rise to the polygonal markings corresponding to the follicle cells, each with a pit at its centre. The follicle cells contain quantities of lipoprotein during this phase of secretion, and are difficult to stain. A method of staining is described which shows that pore canals of two varieties are present in the exochorion layers only. They run from the walls of the pits but do not reach the endochorion. None of the layers of the chorion waterproofs the shell. In the rear end of the shell, the outer polyphenol layer is displaced towards the exochorion, thus increasing the resistant protein layer and reducing the soft protein layer. It is shown that all seven layers are present in the neck, and in the central region of the cap, and that the order of secretion is the same. Modifications are produced by variations in the thickness of the various layers. In the neck, the soft protein layer is reduced; in the cap, the resistant protein layer is reduced while the amber layer is 2µ thick, giving the cap a brown appearance. The soft protein layer is extremely thin and irregular while the exochorion layers are 16 µ thick. Pore canals are again present in two varieties. Some analysis is made of the formation of follicular pits; this appears to be correlated with the thickness of the exochorion and endochorion layers.

scholarly journals The Formation and Structure of the Micropylar Complex in the Egg-Shell of Rhodnius Prolixus Stähl. (Heteroptera Reduviidae)

1947 ◽  
Vol 23 (3-4) ◽  
pp. 213-233 ◽  
Author(s):  
J. W. L. BEAMENT
Keyword(s):  
Follicle Cell ◽  
Rhodnius Prolixus ◽  
Follicle Cells ◽  
Normal Order ◽  
Protein Layer ◽  
Complex Region ◽  
Phase Cycle ◽  
Secretory Products ◽  
Egg Shell ◽  
Pore Canals

An investigation has been made of the junction between the shell and cap in the egg-shell of Rhodnius prolixus. This complex region consists of the thickened rim of the cap connected by a thin sealing bar to the rim of the shell. The secretion of this part of the shell has been followed and compared with the formation of less specialized portions of the shell. The shell has been divided into units, each the product of an individual follicle cell. It has been found that all the seven layers which make up the unspecialized parts of the shell are present in the seal complex; that these consist of five endochorion layers and two exochorion layers in their normal order. The exochorion is secreted around long villi, one from each follicle cell. These give rise to follicular pits in the shell. In this complex region, cells start to secrete at various stages in the seven-phase cycle; their initial secretion is apparently related to the material with which they make contact at that time. After secretion has started, each cell completes the remainder of the cycle. The rim of the cap is the product of four rings of follicle cells; the additional thickness is achieved by an increase in the exochorion layers, secreted around a series of very long follicular pits. The sealing bar, which is produced by one ring of follicle cells, is composed of the inner four layers of the chorion only; the cells do not produce soft endochorion, or exochorion layers. At the cap end of the sealing bar there is the predetermined hatching line. It is apparently produced by the presence in the follicle of cells which are inactive during the secretion of the inner layers, and so prevent co-ordination between the active cells on either side. A weak point is also present at the base of the sealing bar, at the site of other inactive cells, though this fissure is not used at hatching. The rim of the shell is similarly produced by an expansion of the exochorion layers secreted around four rings of follicular villi. Of these, three rings of pits are filled in towards the end of secretion, but the fourth, lying on the upper portion of the rim, remains. These pits become the micropyles and associated structures. There are 200 pits in the completed rim, divided into two groups. About fifteen are micropyles; the remainder are cavities closed at each end, and to which the name ‘pseudomicropyle’ has been given. The pseudomicropyles are formed in a similar way to normal follicular pits, but start in the resistant protein layer, 0.5µ from the inside of the shell. They end in the resistant exochorion, where they are connected to the external surface by small bunches of pore canals. They probably play some part in the respiration of the embryo. The true micropyles form the only free path through the shell. The inner portion of each tube is lined with hydrophilic protein, and the outer portion, which lies slightly posterior to the pseudomicropyles, is composed of hydrophobic lipoprotein. The number of true micropyles is not constant, there being between ten and twenty scattered irregularly around the rim. However, eggs produced by older females contain fewer micropyles; this may account for a higher rate of sterility among these eggs. The cells which form the micropyles and pseudomicropyles are the only ones which do not adhere to the typical cycle of seven secretory products. But in omitting three phases, the attachment of the exochorion to a protein layer is retained. Evidence suggests that the cells forming the micropyles are determined in the earliest stages of secretion by being squeezed out of the pseudomicropylar ring of cells.

The Outer Layers of the Cuticle in the Cockroach Periplaneta americana and the Function of the Oenocytes

1950 ◽  
Vol s3-91 (13) ◽  
pp. 63-72 ◽  
Author(s):  
S. KRAMER ◽  
V. B. WIGGLESWORTH
Keyword(s):  
Honey Bee ◽  
Periplaneta Americana ◽  
Epidermal Cells ◽  
Cuticular Wax ◽  
Cement Layer ◽  
Dermal Glands ◽  
Protein Components ◽  
Egg Shell ◽  
Pore Canals

In the epicuticle of the cockroach there is a cement layer formed, as in other insects, by secretion from certain of the dermal glands at the time of moulting. These dermal glands are widely distributed over the abdominal tergites and sternites in both sexes. Their cell-bodies are atrophied in the mature insect. They differ in this respect from the very numerous dermal glands on the abdominal tergites of the male, which remain distended with vacuoles. The cuticular wax, which is freely exposed on the surface of the cuticle, is thought to be produced by the sub-epidermal oenocytes and to be discharged during the life of the cockroach, perhaps through the pore canals, by the epidermal cells. The oenocytes of the honey-bee are much larger during the height of wax secretion than they are in the foraging bee. The view that the oenocytes are concerned in wax metabolism is compatible with the view that they synthesize the lipoprotein (or wax protein) components of the cuticle and egg-shell.

scholarly journals Fast Dissolving Electrospun Nanofibers Fabricated from Jelly Fig Polysaccharide/Pullulan for Drug Delivery Applications

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 241
Author(s):  
Thangavel Ponrasu ◽  
Bei-Hsin Chen ◽  
Tzung-Han Chou ◽  
Jia-Jiuan Wu ◽  
Yu-Shen Cheng
Keyword(s):  
Drug Delivery ◽  
Water Vapor Permeability ◽  
Electrospun Nanofibers ◽  
Average Diameter ◽  
Xrd Analysis ◽  
Water Soluble ◽  
Vapor Permeability ◽  
Uv Spectrum ◽  
Sem Images ◽  
Triton X

The fast-dissolving drug delivery systems (FDDDSs) are developed as nanofibers using food-grade water-soluble hydrophilic biopolymers that can disintegrate fast in the oral cavity and deliver drugs. Jelly fig polysaccharide (JFP) and pullulan were blended to prepare fast-dissolving nanofiber by electrospinning. The continuous and uniform nanofibers were produced from the solution of 1% (w/w) JFP, 12% (w/w) pullulan, and 1 wt% Triton X-305. The SEM images confirmed that the prepared nanofibers exhibited uniform morphology with an average diameter of 144 ± 19 nm. The inclusion of JFP in pullulan was confirmed by TGA and FTIR studies. XRD analysis revealed that the increased crystallinity of JFP/pullulan nanofiber was observed due to the formation of intermolecular hydrogen bonds. The tensile strength and water vapor permeability of the JFP/pullulan nanofiber membrane were also enhanced considerably compared to pullulan nanofiber. The JFP/pullulan nanofibers loaded with hydrophobic model drugs like ampicillin and dexamethasone were rapidly dissolved in water within 60 s and release the encapsulants dispersive into the surrounding. The antibacterial activity, fast disintegration properties of the JFP/pullulan nanofiber were also confirmed by the zone of inhibition and UV spectrum studies. Hence, JFP/pullulan nanofibers could be a promising carrier to encapsulate hydrophobic drugs for fast-dissolving/disintegrating delivery applications.

Characterization of excretory–secretory products from protoscoleces of Echinococcus granulosus and evaluation of their potential for immunodiagnosis of human cystic echinococcosis

Parasitology ◽  
2004 ◽  
Vol 129 (3) ◽  
pp. 371-378 ◽  
Author(s):  
D. CARMENA ◽  
J. MARTÍNEZ ◽  
A. BENITO ◽  
J. A. GUISANTES
Keyword(s):  
Echinococcus Granulosus ◽  
Cystic Echinococcosis ◽  
Secretory Protein ◽  
Major Protein ◽  
Healthy Donors ◽  
Secretory Products ◽  
Protein Components ◽  
Human Cystic Echinococcosis

This study describes, for the first time, the characterization of excretory–secretory antigens (ES-Ag) from Echinococcus granulosus protoscoleces, evaluating their usefulness in the immunodiagnosis of human cystic echinococcosis. ES-Ag were obtained from the first 50 h maintenance of protoscoleces in vitro. This preparation contained over 20 major protein components which could be distinguished by 1-dimensional SDS–PAGE with apparent masses between 9 and 300 kDa. The culture of of protoscoleces from liver produced a greater variety of excretory–secretory protein components than those from lung. Determination of enzymatic activities of secreted proteins revealed the presence of phosphatases, lipases and glucosidases, but no proteases. These findings were compared to those obtained from somatic extracts of protoscoleces and hydatid cyst fluid products. Immunochemical characterization was performed by immunoblotting with sera from individuals infected by cystic echinococcosis (n=15), non-hydatidic parasitoses (n=19), various liver diseases (n=24), lung neoplasia (n=16), and healthy donors (n=18). Antigens with apparent masses of 89, 74, 47/50, 32, and 20 kDa showed specificity for immunodiagnosis of human hydatidosis. The 89 and 74 kDa components corresponded to antigens not yet described in E. granulosus, whereas proteins of 41–43 kDa and 91–95 kDa were recognized by the majority of the non-hydatid sera studied.

An Egg-Waxing Organ in Ticks

1948 ◽  
Vol s3-89 (7) ◽  
pp. 291-332
Author(s):  
A. D. LESS ◽  
J.W. L. BEAMENT
Keyword(s):  
Inorganic Ions ◽  
Follicle Cells ◽  
Shell Layer ◽  
Critical Temperatures ◽  
Inner Membrane ◽  
Humid Atmosphere ◽  
Yellow Grease ◽  
Accessory Glands ◽  
Pore Canals ◽  
Natural Wax

1. During the oviposition of ticks a glandular organ--the organ of Géné is everted and touches the egg. If it is prevented from everting most of the eggs shrivel rapidly; few hatch even in a humid atmosphere. 2. The waterproofing properties of the normal egg are conferred by a superficial coating of wax, 0.5-2.0 µ. in thickness. In Ornithodorus moubata the wax is secreted and applied solely by Géné's organ. In Ixodes ricinus waterproofing takes place in two stages: an incomplete covering of wax, probably secreted by the lobed accessory glands, is first smeared over the egg during its passage down the vagina; waterproofing is then completed by a further application of wax from Géné's organ after the egg has been laid. Owing to its superficial position on the egg the wax layer is readily attacked by solvents and emulsifiers. 3. The morphology of Géné's organ in O. moubata is described. The gland is a proliferation of the epidermis which lies detached from the cuticle. Its secretion, a watery refractile liquid containing the wax precursor, accumulates between the gland and the cuticle in two horn-like extensions. The wax is probably secreted through pore canals distributed over a narrow zone of cuticle below the horns; the cement covering-layer of the epicuticle does not extend to this zone. 4. The transparent, heat-stable material isolated from the horns of Géné's organ is regarded as the wax precursor. Solubility in water is probably con ferred by chemical linkage with protein. The precursor is taken up from the horns, where it is stored, and is presumably broken down within the gland cells. The wax is then secreted through the pore canals while the protein moiety is retained by the cell. 5. The critical temperatures of the eggs of Ixodidae range from 35° C. in I. ricinus to 44° C. in Hyalomma savignyi; only slightly higher critical temperatures were recorded for Argasidae (45° C. in O. moubata). Eggs with lower critical temperatures are more susceptible to desiccation. The susceptibility of the eggs of a given species is of the same order as that of the parent species; but whereas in Ixodidae the critical temperatures of the egg and the cuticle of the female tick are approximately the same, in Argasidae the critical temperatures of the cuticle are much higher (62° C. in O. moubata). These differences are related to the physical properties of the waxes. The cuticular wax in O. moubata is hard and crystalline (m.p. 65° C), whereas the egg wax is soft and viscous (m.p. 50-54° C). 6. The natural wax from Géné's organ has definite powers of spreading on the surface of the egg and so completing the waterproofing layer. 7. The material extracted with boiling chloroform from egg-shells or from nymphal cuticles separates spontaneously into two fractions, a hard white wax (c. 85 per cent, by weight) and a soft yellow grease (c. 15 per cent.). The properties of these two lipoids differ conspicuously from those of the natural wax. Attempts to deposit the extracted materials on membranes in the form of a waterproofing layer were unsuccessful. 8. Ovulation is described in O. moubata. The shell of the tick egg is secreted by the oocyte itself and not by follicle cells. Three layers can be distinguished in the 24-hour egg: (i) an outer wax layer; (ii) an incomplete layer of granules which reduce ammoniacal silver nitrate; (iii) a shell layer. A fourth layer, the inner membrane (iv), is secreted by the oocyte after incubation for 2-3 days. 9. Both the shell layer and the inner membrane are composed of resistant, elastic protein and are devoid of chitin. The shell layer of the unwaterproofed egg is highly permeable to water and to large molecules with either hydrophilic or lipophilic affinities. The inner membrane is at first freely permeable to water and to inorganic ions. During the course of incubation the wax gradually migrates into the shell material and may reach the inner membrane. As this occurs, the effectiveness of abrasive dusts and of chloroform in promoting increased transpiration through the shell is notably reduced.

Ultrastructure d'une glande sternale tubuleuse des mâles de Speonomus hydrophilus (Coleoptera, Bathysciinae)

1983 ◽  
Vol 61 (3) ◽  
pp. 673-681 ◽  
Author(s):  
Monique Cazals ◽  
Lysiane Juberthie-Jupeau
Keyword(s):  
Sex Pheromone ◽  
Porous Plate ◽  
Free Edge ◽  
Sternal Glands ◽  
Internal Part ◽  
Large Pore ◽  
Secretory Products ◽  
Pore Canals ◽  
Epicuticular Layer

The tubular sternal glands of S. hydrophilus are tegumentary glands present only in the males and were until today unknown. They lie in the segments 6–8 and open between the 8th and 9th segment. They consist of a ramified epithelium made up of prismatic cells. The gland opening is composed of a porous plate connected to an internal cuticular complex. The porous plate itself consists of an epicuticular layer perforated by tiny pores, a mesocuticular layer with large pore canals reaching the pores, then a part with cuticular filaments. All around the porous plate, the mesocuticle makes up a cylindrical excrescence directed towards the secretory part, the free edge of which is prolonged by long mesocuticular plates called pseudomembranes; they are thin, parallel, and penetrate each of the gland cavities. Thus the tubular sternal glands appear as a ramified epidermal invagination; only the internal part of the cuticle is accompanying this invagination. The pseudomembranes might play the same role as an end apparatus for the secretory products. These glands may produce a sex pheromone which would allow the female to recognize the male.

scholarly journals Histo-morphology of genitalia in crossbred dairy cows with kinked cervix

2021 ◽  
Vol 52 (2) ◽  
Author(s):  
V. R. Annie ◽  
K. M. Lucy ◽  
N. Ashok ◽  
S. Maya ◽  
Hiron M. Harshan ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Average Diameter ◽  
Control Group ◽  
System Control ◽  
Cervical Canal ◽  
Connective Tissue Layer ◽  
Significant Difference ◽  
Glandular Structures ◽  
Secretory Products ◽  
Kerala State

The study was conducted on genitalia collected from 100 dairy cows/heifers from the Meat Technology Unit, Mannuthy. The animals brought for slaughter at Meat Technology Unit, Mannuthy were from herds of five different farms (University and Government Undertaking farms) in Kerala state. This included six animals culled on account of factors other than infertility with normal reproductive system (control group) and the remaining animals with a known history of infertility. In total, seven animals showed kinked cervix condition. Cervix was evaluated morphometrically and histologically. Grossly, the cervix was hard, kinked and S-shaped, with a mean length of 9.64 ± 1.19 cm. Average number of annular rings in the cervical canal was 4.14 ± 0.26 with an average diameter of 1.74 ± 0.18 cm. At the external os, diameter of the cervix was less, while at the uterine end, diameter was more. The opening of each cervical ring showed a misalignment instead of a straight line. Histologically, the cervix was lined by simple columnar epithelium with signs of degeneration and desquamation. However, the submucosal layer was extensively infiltrated by collagen fibres. In uterus, there was a significant difference in the number of endometrial glands and height of the glandular epithelial cells which was less when compared to the control group. Muscular layer outer to connective tissue layer was thin and uneven. Alterations of the glandular structures negatively influence the viability of spermatozoa due to the lack of secretory products. This fibrous, collagen rich kinked cervix limits the smooth deposition of the semen into the uterus during artificial insemination and the insufficiently dilated cervix affects its contractibility leading to dystocia and subfertility.

Studies on the Ovarian Follicle Cells of Drosophila

1963 ◽  
Vol s3-104 (67) ◽  
pp. 297-320
Author(s):  
R. C. KING ◽  
ELIZABETH A. KOCH
Keyword(s):  
Ovarian Follicle ◽  
Protein A ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Vitelline Membrane ◽  
Membrane Material ◽  
Adjacent Layer ◽  
Membrane Formation ◽  
Precursor Material ◽  
Egg Shell

Studies are described of the ultrastructure of the follicle cells which invest the oocyte of Drosophila melanogaster at the time of vitelline membrane formation. Of particular interest are organelles made up of endoplasmic reticulum organized into a husk of concentric lamellae which surround lipidal droplets. These epithelial bodies are seen only at the time the vitelline membrane is being formed, and it is assumed therefore that the lipidal material of the epithelial body may be utilized somehow in the fabrication of the vitelline membrane. Cytochemical studies have shown this membrane to contain at least 5 classes of compounds; a protein, two lipids (which may be distinguished by differences in their resistance to extraction by various solvents), and 2 polysaccharides (1 neutral and 1 acidic). Studies were made of vitelline membrane formation in the ovaries of flies homozygous for either of 2 recessive, female-sterile genes (tiny and female sterile). In the case of the ty mutation vitelline membrane material is sometimes secreted between follicle and nurse cells, while in the mutant fes vitelline membrane is observed in rare instances to be secreted between follicle cells and an adjacent layer of tumour cells. In the latter case the vitelline membrane shows altered cytochemical properties. The fact that vitelline membrane can be secreted by follicle cells not adjacent to an oocyte demonstrates that it is the follicle cell rather than the oocyte that plays the major role in the secretion of the precursor material of the vitelline membrane. Subsequently the follicle cells secrete the egg-shell, or chorion, which is subdivided into a dense, compartmented, inner endochorion, and a pale, outer exochorion. A description is given of the ultrastructure of the follicle cells during the secretion of the endochorion and the exochorion. The endochorion contains a protein, a polysaccharide, and a lipid, all of which may be distinguished cytochemically from the vitelline membrane compounds. The exochorion contains large amounts of acidic mucopolysaccharides. Specialized follicle cells form the micropylar apparatus and the chorionic appendages. The formation of the chorion and chorionic appendages is discussed in the light of information gained from abnormalities of the chorions and chorionic appendages seen in ty and fs 2.1 oocytes. Subsequent to the time the egg leaves the ovariole a layer of waterproofing wax is secreted between the vitelline membrane and the chorion.

Immunochemical analysis of the water-soluble fraction of the chick embryo yolk

Development ◽  
1970 ◽  
Vol 24 (1) ◽  
pp. 13-20
Author(s):  
C. E. Grossi ◽  
P. Carinci ◽  
L. Manzoli-Guidotti
Keyword(s):  
Serum Proteins ◽  
Soluble Fraction ◽  
Egg Yolk ◽  
Water Soluble ◽  
Immunochemical Analysis ◽  
Adult Chicken ◽  
Water Soluble Fraction ◽  
Chicken Serum ◽  
Protein Components ◽  
Immunochemical Techniques

By means of immunochemical techniques, the protein components of the water-soluble fraction (WSF) of the egg yolk have been examined in the unincubated egg and during incubation. Anti-ovalbumin and anti-total adult chicken serum antisera have been employed. Ovalbumin can be detected in the unincubated WSF as well as during incubation; its concentration seems to increase during incubation. In the WSF of the unincubated egg, six proteins immunologically related to adult serum proteins can be detected. They correspond to α-livetin, α1-globulin, β-livetin, ovotransferrin (conalbumin) and γ-livetin (two components). β-Livetin disappears after the 14th day of incubation while the other components can be demonstrated till hatching. The findings are discussed in relation to the data available in the literature. The findings are discussed in relation to the data available in the literature.

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