|Year : 2021 | Volume
| Issue : 2 | Page : 61-66
Scanning electron microscopy of vitellogenic oocytes and spawned eggs of the portunid crab Charybdis hellerii (Crustacea-Brachyura) (Milne Edwards, 1867)
Shaikha Mohammed Al-Kandari1, Sohier S El-Sherif2, Sherifa S Hamed2
1 Department of Science, Public Authority for Applied Education and Training, State of Kuwait
2 Department of Zoology, Faculty of Science, Alexandria University, Alexandria, Egypt
|Date of Submission||27-Feb-2019|
|Date of Decision||12-Jun-2020|
|Date of Acceptance||22-Jun-2020|
|Date of Web Publication||09-Jan-2021|
Dr. Shaikha Mohammed Al-Kandari
Department of Science, Public Authority for Applied Education and Training, State of Kuwait
Source of Support: None, Conflict of Interest: None
Background: The portunid crab Charybdis hellerii is an economically critical aquatic species in the Mediterranean region. Several investigators have reported scanning electron microscopy (SEM) observations on some crustacean's eggs' morphology. Going through the previous studies, knowledge regarding the morphology of C. hellerii. vitellogenic oocytes and spawned egg membranes are not available. Aims and Objectives: In the present study, an attempt has been made to describe the morphology and the structure of the membranes of vitellogenic oocytes and the newly spawned eggs to provide necessary information for further studies on the reproductive and evolutionary biology of the crab C. hellerii. Materials and Methods: Samples of ripe pinkish orange ovaries of non-ovigarous females and the spawned incubated eggs of ovigerous females with orange and grey spawns were processed for scanning electron microscopy. The prepared samples were examined in a Zeiss DSM 940 scanning electron microscope. Results: The present SEM study revealed that, vitellogenic oocytes are highly packed with yolk inclusions, which appear to be embedded in a definite acellular matrix and surrounded by a distinct chorion, which is pierced by several pores. The follicle cells appear polygonal in shape and interconnected through thin lateral projections and strongly associated with vitellogenic oocytes. The brooded fertilized eggs are attached through a marked stalk (funiculus) and surrounded by three distinct envelopes, which showed specific ornamentations and variations in their surface topography. The outer envelope coarsely wrinkled, while the middle envelope showed finely wrinkled ornamentation, and the inner envelope appeared with its characteristic spongy, porous appearance. Conclusions: This study denotes a significant difference between mature vitellogenic oocytes inside the ripe ovary and the spawned ova. The differences have been shown in the structure and external ornamentation of their surrounding membranes. Unlike the vitellogenic oocytes, the spawned ova were surrounded by three distinct layers, which are differ in their surface architecture. Such membrane architecture is species specific characteristic and has been thought to be an adaptive feature for brooded fertilized eggs to survive from stressful environmental conditions.
Keywords: Charybdis hellerii, follicle cells, funiculus, vitellogenic oocytes, spawned eggs
|How to cite this article:|
Al-Kandari SM, El-Sherif SS, Hamed SS. Scanning electron microscopy of vitellogenic oocytes and spawned eggs of the portunid crab Charybdis hellerii (Crustacea-Brachyura) (Milne Edwards, 1867). J Microsc Ultrastruct 2021;9:61-6
|How to cite this URL:|
Al-Kandari SM, El-Sherif SS, Hamed SS. Scanning electron microscopy of vitellogenic oocytes and spawned eggs of the portunid crab Charybdis hellerii (Crustacea-Brachyura) (Milne Edwards, 1867). J Microsc Ultrastruct [serial online] 2021 [cited 2021 Aug 3];9:61-6. Available from: https://www.jmau.org/text.asp?2021/9/2/61/306588
| Introduction|| |
The portunid crab Charybdis hellerii is extensively distributed in the Indo-Pacific region and often fished as a commercial catch and has been extending its distribution into the Atlantic Ocean.,,, The species was known to have reached the Mediterranean region.
Scanning electron microscopy (SEM) observations on the morphology of some crustaceans eggs have been reported by several investigators.,,,,,,,,,,,,,,,,,,
Subsequent studies on a number of crustacean eggs have revealed that these eggs are surrounded by an inner chorionic membrane and outer protective covering.,,,,
Morphology and outer ornamentation of crustacean eggs are found to be varied in different species.,,, Ootaxonomy is based chiefly on the species specificity of chorionic architecture, which is constant within the representatives of a species.
Going through the literatures, studies on the morphology of vitellogenic oocytes and spawned eggs of C. hellerii are not available; thus, the present study was conducted to describe the morphology and the structure of the outer membranes of the vitellogenic oocytes inside the ovary on the one hand and that of the newly spawned eggs which are hanged on the female pleopods on the other hand.
| Materials and Methods|| |
Adult ripe and ovigerous females of C. hellerii crab samples were collected from Alexandria Shores and brought alive to the laboratory. Ripe females were determined according to size and the color of the ovary as well as the ventral abdominal flap carapace color. The specimens used in this work included pieces of ripe pinkish-orange ovaries which were removed from nonovigarous females and the spawned incubated eggs which were taken from ovigerous females with orange and grey spawns. All specimens were fixed in 2% buffered glutaraldehyde, washed with in cacodylate buffer (0.05 M, pH 7.4) for 2 h at 4°C. After rinsing in cacodylate buffer, the tissues were post- fixed in 1% osmium tetroxide (OsO4) for 1 h at 4°C and rapidly washed in cacodylate buffer. The specimens were then transferred to an aqueous solution of 1% thiosemicarbazide, for 15 min, followed by an aqueous solution of 1% OsO4 for 30 min at 4°C. After rinsing in distilled water, the specimens were dehydrated in graded ethanol at room temperature, critical point dried, and gold coated according to standard procedures. The prepared parts were examined in a Zeiss DSM 940 scanning electron microscope, in the Electron Microscope Unit at the Alexandria University, Egypt. Photomicrographs were taken at various magnifications.
| Results|| |
The SEM study on C. hellerii vitellogenic oocytes and spawned eggs showed great differences between the vitellogenic oocytes inside the ovary and the spawned ova. These differences appeared in their structure and outer ornamentation of their surrounding membranes. Several pores pierced the outer surfaces of ovarian vitellogenic oocyte were observed [Figure 1]a and [Figure 1]b. Follicle cells appeared closely associated with these oocytes [Figure 1]c. The magnified SEM photographs for the follicle cells showed that these cells are polygonal in shape and interconnected with each other by means of thin lateral projections [Figure 1]d. However, vitellogenic oocyte is highly occupied with yolk inclusions which appeared to be embedded in a clear matrix and surrounded by a distinct chorion [Figure 1]e and [Figure 1]f.
|Figure 1: Vitellogenic oocyte of Charybdis hellerii taken from ripe ovary. (a) The outer surface of the vitellogenic oocyte; (b) magnified part of previous vitellogenic oocyte surface, showing the chorionic surface of vitellogenic oocyte and chorionic pores (arrow); (c) the outer surface of vitellogenic oocyte and the associated follicle cells (arrow); (d) enlarged micrograph showing the connections between the adjacent follicle cells; (e) a part of vitellogenic oocyte showing ooplasm packed with various yolk inclusions (arrows) and the surface of chorion; (f) magnified part of ooplasm of vitellogenic oocyte showing various sizes of yolk inclusions (asterisks) embedded in ooplasm. ch: Chorion, fc: Follicle cells, n: Nucleus, vo: Vitellogenic oocytes|
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The brooded fertilized eggs of C. hellerii showed specific ornamentations [Figure 2]a. Many folds or wrinkles were observed on the surfaces of these eggs. Each spawned egg is surrounded by three different distinct outer, middle, and inner envelopes [Figure 2]b and [Figure 2]c. The three envelopes showed a great variation in their surface topography. The outer envelope possessed coarse, wrinkled ornamentation [Figure 2]d, while the middle envelope showed a fine wrinkled one [Figure 2]e and the inner envelope appeared with its characteristic spongy porous appearance [Figure 2]f. The SEM study of brooded fertilized eggs showed that they were attached to each other through a marked highly twisted stalk (funiculus) [Figure 3]a and [Figure 3]b. It was clearly observed that this funiculus was formed from only the outer envelope, as seen in [Figure 3]c. Brooding eggs, which are undergoing hatching process, are identified through the appearance of a characteristic emerging hatchling side [Figure 3]d and [Figure 3]e.
|Figure 2: Spawned egg of Charybdis hellerii. (a) outer surface ornamentation of spawned egg; (b) the outer envelope (E1) and mid envelope (E2) of spawned egg; (c) the inner envelope (E3) of spawned egg, which is characterized by its spongy porous appearance white arrow (d) magnified part of outer envelope (E1) of spawned egg; (e) magnified part of mid envelope (E2) of spawned egg; (f) magnified part of inner envelope (E3) of spawned egg showing numerous pores on its surface (arrows)|
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|Figure 3: Brooding eggs of Charybdis hellerii. (a) Connection of three brooding eggs through funiculus (arrow). (b) Brooding egg (asterisk), showing highly twisted funiculus (arrow); (c) magnified part of brooding egg, which originated from outer membrane (E1); (d) The brooded egg at the beginning of hatching process. Note: emerging hatchling (arrow); (e) magnified part of the previous brooded egg showing emerging hatchling region (arrow). f: Funiculus|
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| Discussion|| |
In the present study, the vitellogenic ovarian oocytes of C. hellerii are highly condensed with yolk and are surrounded externally by a comparatively thick chorion. This was also coinciding with the observations made by Mazzei et al. who mentioned that before fertilization, the egg of Armadillidium vulgare was surrounded by only one envelope (chorion).
The spongy appearance of chorionic surface of C. hellerii vitellogenic oocytes was owing to the presence of numerous pores. In Portunus pelagicus, El-Sherief observed fine microvilli projected into and through the chorionic pores. However, these fine microvilli were not observed in the present SEM investigation. In Homarus americanus, Talbot observed numerous channels in the chorion of its oocytes. In the same lobster, Schade and Shivers mentioned that the most apparent fine structural feature of vitellogenic ovarian oocytes is the presence of a large number of coated pits. They assume that these pits are involved in the pinocytotic activity of the oocytes. The transmission electron microscopy-based findings of Mollemberg et al. in Mithracidae species from three different genera such as Mithrax hispidus, Mithrax tortugae, Mithraculus forceps, and Omalacantha bicornuta confirm the presence of coated vesicles on the oolemma and many cytoplasmic endocytic vesicles. Such vesicles are responsible for the extracellular uptake of different compounds, a characteristic of the exogenous vitellogenesis. Similarly, the cortical cytoplasm of previtellogenic and vitellogenic oocytes of Astacus leptodactylus were characterized by the presence of coated vesicles. The authors suggested that before the onset of vitellogenesis, follicle cells can deliver other substances into oocytes by receptor-mediated endocytosis.
In the present investigation, the follicle cells were found to be associated with vitellogenic oocytes and connected with each other by means of thin lateral projections. These follicle cells resemble to those described in other decapods species such as the lobster H. americanus,, and marbled crayfish. The investment of follicle cells around oocytes termed as: folliculogenesis” is a prerequisite for heterosynthesis as reported in various crustaceans like Fenneropenaeus indicus and P. pelagicus.
In most decapod crustaceans, fertilized eggs were extruded from the gonopore and attached to the ovigerous hairs within the incubation chamber of the female. The attachment is through a stalk called the funiculus.,,,,,, In the present study, the funiculus function is not only to attach the incubated eggs to the abdominal appendages but also to bind the brooded fertilized eggs to each other. Egg-to-egg adherence phenomenon was observed in other decapod crustaceans such as lobsters in the genus Homarus, and shrimps in genera Palaemonetes and Palaemon macrodactylus. In Sesarma haematocheir, however, egg-to-egg attachment was rarely observed as mentioned by Saigusa et al.
The origin of a funiculus has been discussed in a number of studies. In some decapods, the funiculus formation has no contribution from the egg layer. In the shore crab, Carcinus maenas and in the estuarine crab, S. haematocheir, the funiculus is formed within the abdominal cavity with the aid of long setae., In the narrow-clawed crayfish A. leptodactylus the funiculus is simply formed by deposition of the substance excreted by pleopodal glands. Similarly, In Aegla platensis, the funiculus is formed by addition of an adhesive substance to pleopodal setae. In Austropotamobius pallipes, the funiculus has a dual origin long setae and egg outer layer. In the present investigation, it was clearly observed that the funiculus is derived from the outermost envelope of the egg. This result coincides with an observation made by Yonge, in Homarus vulgaris. Conversely, in the newly laid egg of C. maenas, the highly stretched funiculus consists of two superimposed vitelline envelopes.
SEM study revealed that the spawned eggs of C. hellerii are enfolded by three distinct envelopes outer, middle, and inner envelopes. The egg envelopes are elaborated by follicle cells and laid down in a well-defined sequence. These envelopes are extracellular structures that surround the egg cell and the embryo after fertilization. Their basic function is to protect the embryo from potentially harmful aspects of the external environment. A survey on the morphology and the structure of crustaceans' egg envelops showed that they are greatly varies among the different species. The eggs of the copepod Calanus sinicus had revealed a complex five-layered structure, which seemed to be originated from the egg. The second to the fifth layers were newly formed after spawning, while the first layer, which might be a vitelline envelope, separated from the cell membrane just after spawning. Hinsch and Cone reported that the mature oocyte of Libinia emarginata has an egg membrane with two distinct layers, as observed by electron microscope. In the swimming crab, Portunus trituberculatus, two membranes formed after fertilization and the outer membrane, which played an important role in attachment to the pleopods. Minagawa et al. mentioned the presence of the two-layer egg membrane at the prematuration stage in the crab Ranina ranina. In the portunid crab Portunus sanguinolentus, the newly spawned eggs were spherical and surrounded by two transparent membranes, an inner and outer membrane. Saigusa et al. determined three envelopes enfolding the egg of the estuarine crab S. haematocheir by the use of transmission electron microscope. He added that the outermost layer consists of two further sublayers. In the crayfish A. leptodactylus, the egg case is made of three layers; the external, the middle, and the inner layers. All layers are composed of an electron-dense material; the most distinct ultrastructural feature is the presence of polyhedral grains, which are interspersed with multiple aeropylar areas and channels in the middle layer. In addition, the second (middle) layer consists of two sublayers of equal thickness but with variable grain sizes and aeropyle structures. The third and innermost layer is made of tightly packed grains, smaller than those in the middle layer. It includes a few, small aeropylar channels. In Oratosquilla massavensis, spawned eggs were covered by the characteristic chorion with three different regions: the marginal, central, and frontal regions. The most conspicuous characteristics are the appearance of irregularly shaped projections and dark spots. In the central region, the author suggested that these spots appeared to be a secretion released from conspicuous openings between the projections.
In the present investigation, the spawned eggs of C. hellerii differ from those before spawning in their outer ornamentation. The important difference is the presence of wrinkles in the outer and middle envelopes. These wrinkles or folds certainly may increase the surface area of the attaching membrane and may assist this outer covering as a protective and large coat for the time when the egg grows up during embryogenesis. Different egg ornamentation was also observed in other crustacean species such as anostracans of the genus Chirocephalus, anostracans of the genus Branchinecta,,,, in P. pelagicus, A. leptodactylus, and O. massavensis.
From the present investigation, it was corroborated that hatching process of brooding eggs was identified through the appearance of a characteristic emerging hatchling region. This in agreement with Vogt et al. who found similar structure during the hatching process of marbled crayfish brooding eggs.
In summary, the vitellogenic oocytes of C. hellerii are surrounded by one layer “the chorion,” while the newly spawned eggs, which are hanged on the female pleopods, are enfolded by three distinct layers. It seemed that the nature of ornamentation of C. hellerii spawned egg membranes may have a protective role in keeping them as safe as possible and add more protection against stressful conditions in the aquatic environment. The information regarding the egg morphology of C. hellerii, is needed to indicate phylogenetic relationships among the crab taxa.
The authors gratefully thank the Electron Microscope Unit at the Alexandria University for allowing the research to be carried out on their premises.
Financial support and sponsorship
This study was supported by financial assistance provided by Kuwait ministry of education.
Conflicts of interest
There are no conflicts of interest.
| References|| |
Gomez O, Martinez-Iglesias J. Reciente hallazgo de la especie indopacifica Charybdis hellerii
(A. Milne Edwards, 1867) (Crustacea
) en aguas cubanas. Caribb J Sci 1990;26:70-2.
Lemaitre R. Charybdis hellerii
(Milne Edwards, 1867), a non-indigenous portunid crab (Crustacea
) discovered in the Indian River lagoon system of Florida. Proc Biol Soc Wash 1995;108:643-8.
Tavares M, de Mendonca JB. Charybdis hellerii
(A. Milne Edwards, 1867) (Brachyura
), eighth nonindigenous marine decapod recorded from Brazil. Crustac Res 1996;25:151-7.
Mantelatto FL, Dias LL. Extension of the known distribution of Charybdis hellerii
(A. Milne Edwards 1867) (Decapoda
) along the western tropical South Atlantic. Crustaceana 1999;72:617-20.
Por FD. Lessepsian Migration: The Influx of the Red Sea Biota into the Mediterranean by Way of the Suez Canal. 1st
ed.. Berlin: Springer Verlag; 1978.
Brown GG. Ultrastructural studies of sperm morphology and sperm-egg interaction in the decapod Callinectes sapidus
. J Ultrastruct Res 1966;14:425-40.
Cheung T. The development of egg-membranes and egg attachment in the shore crab, Carcinus
. J Mar Biol Assoc UK 1966;46:373-400.
Hinsch GW. Penetration of the oocyte envelope by spermatozoa in the spider crab. J Ultrastruct Res 1971;35:86-97.
De Maeyer-Criel G, Fautretz-Firlefyn N, Fautretz J. Formation de la membrane de fecundation de l' oeuf d' Artemia salina
. Arch Develop Biol 1977;183:223-231.
Goudeau M, Lachaise F. Fine structure and secretion of the capsule enclosing the embryo in a crab (Carcinus maenas
(L.)). Tissue Cell 1980a;12:287-308.
Goudeau M, LaChaise F. 'Endogenous yolk' as the precursor of a possible fertilization envelope in a crab (Carcinus maenas
). Tissue Cell 1980b; 12:503-12.
El-Sherief S. A scanning electron microscopic study on the egg of Portunus pelagicus
). Proc Zool Soc A R Egypt 1987;14:23-32.
Pillai MC, Clark WH Jr. Hatching envelope formation in shrimp (Sicyonia ingentis
) ova: Origin and sequential exocytosis of cortical vesicles. Tissue Cell 1988;20:941-52.
Talbot P, Goudeau M. A complex cortical reaction leads to formation of the fertilization envelope in the lobster, Homarus
. Gamete Res 1988;19:1-8.
Pillai MC, Clark WH Jr. Development of cortical vesicles in Sicyonia ingentis
ova: Their heterogeneity and role in elaboration of the hatching envelope. Mol Reprod Dev 1990;26:78-89.
Hirose E, Toda H, Saito Y, Watanabe H. Formation of the multiple-layered fertilization envelope in the embryo of Calanus sinicus
). J Crustac Biol 1992;12:186-92.
Kang X, Wang G, Chen J. Studies on the egg membrane variation and egg attachment in Scylla serrata
. J Fish China/Shuichan Xuebao 2000;24:500-2.
Palomino J, Moreno RD, Bustamante E, Messen L, Dupre E, Barros C, et al
. Egg coats of the rock shrimp Rhynchocinetes
typus: Ultrastructural characterization and their function during fertilization. J Exp Zool 2002;293:632-40.
Saigusa M, Terajima M, Yamamoto M. Structure, formation, mechanical properties, and disposal of the embryo attachment system of an estuarine crab, Sesarma haematocheir
. Biol Bull 2002;203:289-306.
Ying X, Yang W. Structure and formation of the embryo attachment system of Eriocheir sinensis
. Acta Zool Sin Dongwu Xuebao 2005;51:852-61.
Silva JR, Cruz-Landim C. Macroscopic aspects and scanning electron microscopy of the ovaries of the spiny lobster Panulirus
) Braz J Morphol Sci 2006;23:479-86.
Pawlos D, Korzelecka-Orkisz A, Rościszewska E, Formicki K. Egg case ultrastructure in the narrow-clawed crayfish Astacus leptodactylus
Eschscholtz, 1823 (Decapoda
, Astacidae). Crustaceana 2011;84:623-33.
El-Sherief S. SEM study on the structural properties and the site of formation of egg membranes of Carcinus maenas
(L). Indian J Z 1990;1:1-9.
El-Sherief S, El-Khodary G, Amal Z. Ovarian cycle and scanning electron micrographs of the spawned egg of female mantis shrimp Oratosquilla massavensis
(Alexandria, Egypt). J Basic Appl Zool 2012;65:116-24.
Yonge CM. The nature and significance of the membranes surrounding the developing eggs of Homarus vulgaris
and other Decapoda
. Proc Zool Soc Lond A 1938;107:499-517.
Mawson ML, Yonge CM. The origin and nature of the egg membranes in Chirocephalus diaphanous
. Quart J Microsc Sci 1938;80:553-65.
Linder HJ. Studies o the fresh water fairy shromp Chrocephalopsis bundyi
(Forbes). 2. Histochemistry of egg-shell formation. J Morphol 1960;107:259-83.
Dupré EM, Barros C. In vitro
fertilization of the rock shrimp, Rhynchocinetes typus
): A review. Biol Res 2011;44:125-33.
Mura G, Accordi F, Rambini M. Studied on the resting eggs of some fresh water fairy shrimps of the genus Chirocephalus
: Biometry and scanning electron microscopic morphology (Branchiopoda
). Crustaceana 1978;35:190-9.
Belk D. Identification of species in the conchostracan genus Eulimnadia
by egg shell morphology. J Crustac Biol 1990;9:115-25.
Mura G. SEM morphology of resting eggs in the species of the genus Branchinecta
from North America. J Crustac Biol 1991;11:432-6.
Mura G. Pattern of egg morphology in Thamnocephalids and Streptocephalids of the New World (Crustacea
, Anostroca). Crustaceana 1992;62:300-11.
Gaino E, Abongiovanni. Comparative morphplogy of Epithemata (Polar chorionic Structures) in the egg of Ephemerella iginta Ephemeroptera: Ephemerellidae. Trans Am Microsc Soc 1992;111:255-65.
Felgenhauer B. Techniques for preparing crustaceans for scanning electron microscopy. J Crustac Biol 1987;7:71-6.
Mazzei V, Sinatra F, Villaggio G, Longo G. Egg envelopes of Armadillidium vulgare
(Latreille, 1804) (Crustacea
, Isopoda Oniscidea
): Ultrastructure and lectins binding. Microsc Res Tech 2016;79:792-8.
Talbot P. The ovary of the lobster, Homarus americanus
. II. Structure of the mature follicle and origin of the chorion. J Ultrastruct Res 1981;76:249-62.
Schade ML, Shivers RR. Structural modulation of the surface and cytoplasm of oocytes during vitellogineses in the lobster Homarus
Americans. An electron microscope protein tracer study. J Morphol 1980;163:13-26.
Mollemberg M, José Zara F, Santana W. Morphology and ultrastructure of the adult ovarian cycle in Mithracidae
, Majoidea). Helgol Mar Res 2017;71:1-14.
Petrescu AM, Moldovan L, Zarnescu O. Morphology and ultrastructure of the somatic cells in Astacus leptodactylus
ovary. J Morphol 2016;277:118-27.
Vogt G, Tolley L, Scholtz G. Life stages and reproductive components of the Marmorkrebs (marbled crayfish), the first parthenogenetic decapod crustacean. J Morphol 2004;261:286-311.
Diwan AD, Mohamed SK. Reproductive physiology. In: Diwan A, Modayil MJ, editors. Physiology of Marine white Shrimp Fenneropenaeus indicus
. Delhi, India: Narendra Publishing House; 2007. p. 165-201.
Ravi R, Manisseri MK, Sanil NK. Ovarian maturation and oogenesis in the blue swimmer crab, Portunus pelagicus
). Acta Zool 2012;94:291-9.
Yonge CM. Permeability and properties of the membranes surrounding the developing egg of Homarus vulgaris
. J Mar Biol Assoc U K 1946;26:432-8.
Fisher W, Clark W. Eggs of Palaemon macrodctylus
: I. Attachment to the polypods and formations of the outer investment coat. Biol Bull 1983;164:189-200.
Goudeau M, Lachaise F. Structure of the egg funiculus and deposition of embryonic envelopes in a crab. Tissue Cell 1983;15:47-62.
Loureiro TG, Almerão MP, Faccioni-Heuser MC, Bond-Buckup G, de Araujo PB. External morphology and ultrastructure of tegumental glands of Aegla platensis
, Aeglidae) Pleopods: Might They Play A Role in Egg Attachment? Res Ecol 2019;1:1-7.
Talbot P, Harper R. Abnormal egg stalk morphology is correlated with clutch attrition in laboratory-maintained lobsters (Homarus
). Biol Bull 1984;166:349-56.
Burkenroad MD. Reproductive activities of decapod Crustacea
. Am Nat 1947;81:392-8.
Thomas WJ. Aspects of egg attachment in Austropotamobius pallipes
(Lereboullet, 1858) (Decapoda
, Astacidae). Crustaceana 1991;61:287-93.
Gaino E, Mazzinmi M. Follicle cell activity in the ovarioles of Habrophlebia eldae
(Ephemeroptera: Leptophlebiiae). Trans Am Microsc Soc 1990;109:300-10.
Hinsch G, Cone M. Ultrastructural observation of vitellogenesis in the spider crab, Libinia emarginata
L. J Cell Biol 1969;40:336-42.
Hamasaki K, Fukunaga K, Nogami K, Maruyama K. Egg-laying and process of egg attachment to the pleopods in the swimming crab Portunus trituberculatus
. Saibai Giken 1991;19:85-92.
Minagawa M, Chiu JR, Kudo M, Ito F, Takashima F. Female reproductive biology and oocyte development of the red frog crab, Ranina ranina
, off Hachijojime, Izu Island Japan. Mar Biol 1993;115:613-23.
Samuel JN, Soundarapandian P. Embryonic development of commercially important portunid crab Portuns sanguinolentus
(Herbst). Int J Anim Vet Adv 2009;1:32-8.
Munuswamy N, Subramonium T. Scanning electron microscope studies on the egg shell of two freshwater fairy shrimps, Streptocephalus dichotomus
and Branchinella kugenumaenis
). Cytobios 1983;37:181-6.
Mura G, Thiéty A. Taxonomical significance of scanning electron microscopic morphology of the Euphyllopods resting eggs from Morocco. Part I: Anostraca. Vieet Milieu 1986;36:125-31.
[Figure 1], [Figure 2], [Figure 3]