scholarly journals The Origin and Fate of Annulate Lamellae in Maturing Sand Dollar Eggs

1959 ◽  
Vol 5 (1) ◽  
pp. 117-121 ◽  
Author(s):  
R. W. Merriam
Keyword(s):  
Nuclear Envelope ◽  
Annulate Lamellae ◽  
Dense Matrix ◽  
Sand Dollar ◽  
Variable Size ◽  
Mature Ovum ◽  
Physical Relationship ◽  
Cytoplasmic Vesicles ◽  
Dendraster Excentricus ◽  
Cytoplasmic Side

Electron micrograph evidence is presented that the nuclear envelope of the mature ovum of Dendraster excentricus is implicated in a proliferation of what appear as nuclear envelope replicas in the cytoplasm. The proliferation is associated with intranuclear vesicles which apparently coalesce to form comparatively simple replicas of the nuclear envelope closely applied to the inside of the nuclear envelope. The envelope itself may become disorganized at the time when fully formed annulate lamellae appear on the cytoplasmic side and parallel with it. The concept of interconvertibility of general cytoplasmic vesicles with most of the membrane systems of the cytoplasm is presented. The structure of the annuli in the annulate lamellae is shown to include small spheres or vesicles of variable size embedded in a dense matrix. Dense particles which are about 150 A in diameter are often found closely associated with annulate lamellae in the cytoplasm. Similar structures in other echinoderm eggs are basophilic. In this species, unlike other published examples, the association apparently takes place in the cytoplasm only after the lamellae have separated from the nucleus. If 150 A particles are synthesized by annulate lamellae, as their close physical relationship suggests, then in this species at least the necessary synthetic mechanisms and specificity must reside in the structure of annulate lamellae.

Membranous alterations in the cytoplasm and nucleus in a primitive neuroectodermal tumor of the brain

1978 ◽  
Vol 36 (2) ◽  
pp. 628-629
Author(s):  
C. N. Sun ◽  
C. Araoz ◽  
H. J. White
Keyword(s):  
Nuclear Envelope ◽  
Tumor Cells ◽  
Osmium Tetroxide ◽  
Primitive Neuroectodermal Tumor ◽  
Uranyl Acetate ◽  
Neuroectodermal Tumor ◽  
Annulate Lamellae ◽  
Lead Citrate ◽  
Thin Sections ◽  
The Brain

The ultrastructure of a cerebral primitive neuroectodermal tumor has been reported previously. In the present case, we will present some unusual previously unreported membranous structures and alterations in the cytoplasm and nucleus of the tumor cells.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4% glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1% buffered osmium tetroxide for one hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate.In the cytoplasm of the tumor cells, we found paired cisternae (Fig. 1) and annulate lamellae (Fig. 2) noting that the annulate lamellae were sometimes associated with the outer nuclear envelope (Fig. 3). These membranous structures have been reported in other tumor cells. In our case, mitochondrial to nuclear envelope fusions were often noted (Fig. 4). Although this phenomenon was reported in an oncocytoma, their frequency in the present study is quite striking.

scholarly journals Postmitotic annulate lamellae assembly contributes to nuclear envelope reconstitution in daughter cells

2019 ◽  
Vol 294 (27) ◽  
pp. 10383-10391 ◽  
Author(s):  
He Ren ◽  
Guangwei Xin ◽  
Mingkang Jia ◽  
Shicong Zhu ◽  
Qiaoyu Lin ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Annulate Lamellae ◽  
Daughter Cells

scholarly journals Rethinking competence in marine life cycles: ontogenetic changes in the settlement response of sand dollar larvae exposed to turbulence

2015 ◽  
Vol 2 (6) ◽  
pp. 150114 ◽  
Author(s):  
Jason Hodin ◽  
Matthew C. Ferner ◽  
Gabriel Ng ◽  
Christopher J. Lowe ◽  
Brian Gaylord
Keyword(s):  
Life Histories ◽  
Immature Stage ◽  
Life Cycles ◽  
Sand Dollar ◽  
Ontogenetic Changes ◽  
Marine Animals ◽  
Settlement And Metamorphosis ◽  
Two Phases ◽  
Pass Through ◽  
Dendraster Excentricus

Complex life cycles have evolved independently numerous times in marine animals as well as in disparate algae. Such life histories typically involve a dispersive immature stage followed by settlement and metamorphosis to an adult stage on the sea floor. One commonality among animals exhibiting transitions of this type is that their larvae pass through a ‘precompetent’ period in which they do not respond to localized settlement cues, before entering a ‘competent’ period, during which cues can induce settlement. Despite the widespread existence of these two phases, relatively little is known about how larvae transition between them. Moreover, recent studies have blurred the distinction between the phases by demonstrating that fluid turbulence can spark precocious activation of competence. Here, we further investigate this phenomenon by exploring how larval interactions with turbulence change across ontogeny, focusing on offspring of the sand dollar Dendraster excentricus (Eschscholtz). Our data indicate that larvae exhibit increased responsiveness to turbulence as they get older. We also demonstrate a likely cost to precocious competence: the resulting juveniles are smaller. Based upon these findings, we outline a new, testable conception of competence that has the potential to reshape our understanding of larval dispersal and connectivity among marine populations.

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