Early embryology af the marsupials Isoodon macrourus and Perameles nasuta

1976 ◽  
Vol 24 (3) ◽  
pp. 361 ◽  
Author(s):  
AG Lyne ◽  
DE Hollis
Keyword(s):  
Electron Microscopy ◽  
Outer Surface ◽  
Zona Pellucida ◽  
Light And Electron Microscopy ◽  
Blastocyst Stage ◽  
Embryonic Cells ◽  
Crystalloid Inclusions ◽  
Early Mouse ◽  
Number Of Cells ◽  
Rabbit Embryos

Twelve embryos, ranging from a four-celled stage to late unilaminar blastocysts, were obtained from the bandicoots I. macrourus and P. nasuta and examined by light and electron microscopy. These early stages covered at least one-quarter of the 12.5-day gestation period. The three non-cellular egg membranes characteristic of marsupials (zona pellucida, mucoid coat and shell membrane) were present, although the zona was sometimes absent or discontinuous in the intermediate and late unilaminar blastocysts examined. At the four-celled stage the blastomeres were close to the zona, but they had lost contact with each other, probably due to the extrusion of yolk, a phenomenon which has been described in other marsupials. The embryo did not increase in diameter until it was composed of at least 75 contiguous cells, which were in contact with the zona. In several of the larger blastocysts the protoderm cells had lost contact with the zona. Subsequently, the number of cells increased considerably and they were flattened against the egg membranes to form the late unilaminar blastocyst stage. Electron microscopy of the protoderm cells revealed the presence of numerous microvilli, particularly on the outer surface, and a range of other structures as great as those found in eutherian mammals. Remnants of spindle bridges were common in one 75-celled embryo. The yolk material in the blastocoele was also composed of a variety of structures, including small crystalloid inclusions composed of hexagonal units about 8-10 nm in diameter. Similar crystalloids have been described in the cells of early mouse and rabbit embryos and in egg and embryonic cells of various amphibians.

Endodermal formation in blastocytes of the marsupials Isoodon macrousus and Perameles nasuta

1977 ◽  
Vol 25 (2) ◽  
pp. 207 ◽  
Author(s):  
DE Hollis ◽  
AG Lyne
Keyword(s):  
Electron Microscopy ◽  
Outer Surface ◽  
Zona Pellucida ◽  
Morphological Changes ◽  
Light And Electron Microscopy ◽  
Didelphis Virginiana ◽  
Continuous Layer ◽  
Shell Membrane ◽  
American Opossum ◽  
Embryonic Region

Eleven embryos, ranging from partly to fully bilaminar blastocysts, were obtained from the bandicoots I. macrourus and P. nasuta and were examined by light and electron microscopy. The morphological changes which occurred during the differentiation of the endoderm and ectoderm are described. The shell membrane was thinner than it was in unilaminar blastocysts and had a deposit of material of irregular thickness on its outer surface. The mucoid coat and zona pellucida were absent or discontinuous. Endoderm formation was first observed in blastocysts about 1.0 mm in diameter. Cells migrated inwards from regions of thickened protoderm to form a continuous layer of similar flattened cells - the endoderm - beneath the protoderm, which then became the ectoderm. The blastocysts were fully bilaminar when they were 1.5-1.9 mm in diameter. At this stage the ectoderm was composed of two distinct regions, an embryonic region of cuboidal cells and a non-embryonic region of flattened cells resembling the cells of the endoderm. The formation of the endoderm in bandicoots closely resembles that described in other marsupials, except the American opossum Didelphis virginiana in which endoderm cells are released into the blastocoele before they form a continuous layer.

An unusual blastocyst stage of the marsupial Isoodon macrourus

1977 ◽  
Vol 25 (2) ◽  
pp. 225 ◽  
Author(s):  
AG Lyne ◽  
DE Hollis
Keyword(s):  
Electron Microscopy ◽  
Zona Pellucida ◽  
Light And Electron Microscopy ◽  
Blastocyst Stage ◽  
Cell Divisions

Four blastocysts, identical in size (diameter 1.1 mm) and appearance, were obtained from one uterus of a short-nosed bandicoot I. macrourus and examined by light and electron microscopy. These blastocysts were unusual in that each one had a conspicuous region of protoderm about 0.3-0.5 mm in width and mostly more than one cell thick. The remainder of the protoderm was thin and unilaminar. Cell divisions were more numerous in the thickened region than in the remainder of the protoderm. Some entire cells and blebs of cytoplasm had been shed or were being shed from the thickened region into the blastocoele. The egg membranes were similzr to those of bilaminar blastocysts, the shell membranes being intact and about 1.0 um thick, and the mucoid coat and zona pellucida being discontinuous.

Further observations on nucleolar tails in amphibian oocytes

1991 ◽  
Vol 99 (3) ◽  
pp. 515-521
Author(s):  
PEDRO LEÓN ◽  
JAMES KEZER ◽  
ERIC SCHABTACH
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Outer Surface ◽  
Light And Electron Microscopy ◽  
Nuclear Pores ◽  
Core Component ◽  
Amphibian Species ◽  
Attachment Structures ◽  
Convoluted Tubules

Large oocytes from some amphibian species possess beaded or unbeaded intranuclear tails that penetrate the extrachromosomal nucleoli through a distinct pit in their surface and attach to the central core component Here we show, using light and electron microscopy, that tails anchor nucleoli to the nuclear envelope through intricate attachment structures. These structures are composed of interconnected spherical masses containing highly convoluted tubules and associated extratubular proteins, directly directly in contact with the inner nuclear membrane. Fibers emerging from the nuclear pores seemingly hold the attachment complex in place. Beads on the nucleolar tails are formed by the accumulation of proteins on the outer surface of smooth tubules. The function of these intranuclear tubules is unknown

scholarly journals H3K27me3 at Pericentromeric Heterochromatin is a Defining Feature of the Early Mouse Blastocyst

2022 ◽  
Author(s):  
Mélanie Pailles ◽  
Mélanie Hirlemann ◽  
Vincent Brochard ◽  
Martine Chebrout ◽  
Jean-François Oudin ◽  
...  
Keyword(s):  
Blastocyst Stage ◽  
Pericentromeric Heterochromatin ◽  
Embryonic Cells ◽  
Mouse Development ◽  
Mouse Blastocyst ◽  
Major Satellite ◽  
Post Translational Modifications ◽  
Early Mouse ◽  
Diffuse Distribution

Abstract Early mouse development is characterized by structural and epigenetic changes at the chromatin level while cells progress towards differentiation. At blastocyst stage, the segregation of the three primordial lineages is accompanied by establishment of differential patterns of DNA methylation and post-translational modifications of histones, such as H3K27me3. In this study, we have analysed the dynamics of H3K27me3 at pericentromeric heterochromatin (PCH) during development of the mouse blastocyst, in comparison with cultured embryonic cells. We show that this histone modification is first enriched at PCH in the whole embryo and evolves into a diffuse distribution in epiblast during its specification and maturation. Concomitantly, the level of transcription from major satellite decreases. Stem cells derived from blastocyst (naïve ESCs and TSCs) do not fully maintain the H3K27me3 enrichment at PCH. Moreover, the dynamic of H3K27me3 at PCH during in vitro conversion from naïve to primed pluripotent state and during ESCs derivation suggests that the mechanisms underlying the control of this histone mark at PCH are different in embryo and in vitro. We also conclude that the non-canonical presence of H3K27me3 at PCH is a defining feature of embryonic cells in the young blastocyst before epiblast segregation.

Studies on the development of F1 embryos from inter-strain crosses involving DDK mice

Development ◽  
1977 ◽  
Vol 38 (1) ◽  
pp. 211-216
Author(s):  
Noboru Wakasugi ◽  
Mitsuyo Morita
Keyword(s):  
Blastocyst Stage ◽  
Small Cell ◽  
Mouse Embryos ◽  
Cleavage Rate ◽  
Cytoplasmic Factor ◽  
Cell Numbers ◽  
Significant Difference ◽  
The Mean ◽  
Early Mouse ◽  
Number Of Cells

The development of the early mouse embryos was investigated from 36 to 84 h after the presumed time of fertilization. The mean number of cells constituting the embryo from the intra-strain crosses of three strains at 84 h of development was as follows: DDK, 22·7; BS, 43·1 and 1TES, 62·0. A significant difference was observed in the cleavage rate of the embryo between DDK and the other two strains. The F1 embryos from the crosses of BS females × DDK males and ITES females × DDK males showed almost the same progress of development as BS and ITES embryos, respectively. Therefore, it is concluded that the early development of the F1 embryos is regulated mainly by the factors from the mother. The morulae from the semi-sterile cross, DDK females × BS males, showed conspicuously small cell numbers as compared with their litter-mates that developed to the blastocyst stage. It is inferred that the discrimination is already made during cleavage between the fortunate survivors and the lethal embryos due to the incompatibility between the cytoplasmic factor of DDK eggs and alien spermatozoa.

Cell migration from the chick olfactory placode: a light and electron microscopic study

Development ◽  
1982 ◽  
Vol 69 (1) ◽  
pp. 47-59
Author(s):  
A. S. Mendoza ◽  
W. Breipohl ◽  
F. Miragall
Keyword(s):  
Electron Microscopy ◽  
Cell Migration ◽  
Light And Electron Microscopy ◽  
Olfactory Mucosa ◽  
Electron Microscopic ◽  
Olfactory Placode ◽  
The Third ◽  
Epitheloid Cells ◽  
Migration Of Cells ◽  
Number Of Cells

The diflferentiation of the olfactory placode in the chick has been studied using light and electron microscopy. Special attention was paid to the appearance of neuronal cells within the placodal ectodermal thickening, the migration of cells out of this tissue and the appearance of the first fila olfactoria in the differentiating olfactory mucosa. Between the third and fifth day of incubation a large number of cells is observed leaving the base of the invaginating olfactory placode, often in contact with thin axon bundles. These cells are characterized by a well-developed Golgi apparatus, a considerable number of mitochondria and dense-core vesicles. The morphology of these migrating cells resembles that of cells observed near the basement membrane within the developing olfactory epithelium and is clearly different from the mesenchymal cells which are filled with polyribosomes. At the sixth day of incubation thick axon bundles can be observed within the epithelium and the underlying lamina propria. The possible fate of the migrated epitheloid cells is discussed.

scholarly journals Development of early mouse and rabbit embryos without zona pellucida

Reproduction ◽  
1981 ◽  
Vol 61 (2) ◽  
pp. 303-306 ◽  
Author(s):  
O. J. Rottmann ◽  
W. W. Lampeter
Keyword(s):  
Zona Pellucida ◽  
Early Mouse ◽  
Rabbit Embryos

Simultaneous observations of immunolabeled frozen sections in lm and em

1978 ◽  
Vol 36 (2) ◽  
pp. 164-165
Author(s):  
K. T. Tokuyasu ◽  
J. Slot ◽  
S. J. Singer
Keyword(s):  
Electron Microscopy ◽  
Fluorescent Microscopy ◽  
Light And Electron Microscopy ◽  
Frozen Sections ◽  
Cover Glass ◽  
Rat Pancreas ◽  
Light Microscopic Observation ◽  
Rabbit Igg ◽  
Ultrathin Frozen Sections ◽  
Number Of Cells

Immunofluorescent microscopy is more suitable for the analysis of a large number of cells, often greater in the sensitivity for the detection of antigens, and more readily applicable for the identification of multiple antigens than immunoe1ectron microscopy. For combining these features of fluorescent microscopy with the superior resolution of electron microscopy, we attempted to observe the same immunolabeled ultrathin frozen sections with both light and electron microscopy.Ultrathin frozen sections of rat pancreas fixed in a mixture of 2% formaldehyde and 0.2% g1utaraldehyde for 1 hr at 4°C were first immunostained with rabbit anti-rat amylase antibodies, then very lightly with ferritin-goat anti-rabbit IgG conjugates and heavily with rhodamine-goat anti-rabbit IgG conjugates. For light microscopic observation, grids were suspended underneath the cover glass with a very thin layer of 50-90% glycerol and the cover glass was separated from the slide glass by a spacer to avoid the contact of the grid with the slide glass. After the light microscope observation, the grids were floated on 0.1 M phosphate buffer by dissolving glycerol into the buffer and processed for electron microscopy.

Quantitative morphological analysis of early mouse embryogenesis in vitro

Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 91-100
Author(s):  
Russell L. Deter
Keyword(s):  
Morphological Analysis ◽  
Light And Electron Microscopy ◽  
Three Dimensional ◽  
Perfusion Culture ◽  
Blastocyst Stage ◽  
Mouse Development ◽  
Mesh Structure ◽  
Early Mouse ◽  
Quantitative Morphological Analysis

To facilitate a quantitative morphological analysis of early mouse development under controlled conditions, a perfusion culture system capable of supporting embryogenesis to blastocyst stage has been developed. The use of a mesh system allows identification of individual embryos by position, and control of their orientation during culture and preparation for light and electron microscopy. Quantitative evaluation of tissue-processing procedures has permitted selection of conditions which reduce changes in linear dimensions to −1·6 ± 1·8 % in two-cell embryos. Through the definition of a coordinate system based on mesh structure and the development of a special sectioning procedure, sections can be localized within the intact embryo and three-dimensional coordinates given to any element of embryo volume.

The Morphology of Vacuolated Cells in the Liver Following Administration of Vitamin A.

1973 ◽  
Vol 31 ◽  
pp. 408-409
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo ◽  
Fawzia Batti
Keyword(s):  
Electron Microscopy ◽  
Body Weight ◽  
Vitamin A ◽  
Light And Electron Microscopy ◽  
Liver Cells ◽  
Prominent Feature ◽  
Vascular Space ◽  
Vacuolated Cell ◽  
Vacuolated Cells ◽  
Vacuolated Cytoplasm

Vacuolated cells in the liver of young rats were studied by light and electron microscopy following the administration of vitamin A (200 units per gram of body weight). Their characteristics were compared with similar cells found in untreated animals.In rats given vitamin A, cells with vacuolated cytoplasm were a prominent feature. These cells were found mostly in a perisinusoidal location, although some appeared to be in between liver cells (Fig. 1). Electron microscopy confirmed their location in Disse's space adjacent to the sinusoid and in recesses between liver cells. Some appeared to be bordering the lumen of the sinusoid, but careful observation usually revealed a tenuous endothelial process separating the vacuolated cell from the vascular space. In appropriate sections, fenestrations in the thin endothelial processes were noted (Fig. 2, arrow).

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