Interactions of blastomeres suggest changes in cell surface adhesiveness during the formation of inner cell mass and trophectoderm in the preimplantation mouse embryo

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 133-152
Author(s):  
Susan J. Kimber ◽  
M. Azim ◽  
H. Surani ◽  
Sheila C. Barton

Whole 8-cell morulae can be aggregated with isolated inner cell masses from blastocysts. On examining semithin light microscope sections of such aggregates we found that cells of the morula changed shape and spread over the surface of the ICM, thus translocating it to the inside of the aggregate. Using single cells from 8-cell embryos in combination with single cells from other stage embryos or isolated ICMs we show that 1/8 blastomeres spread over other cells providing a suitably adhesive surface. The incidence of spreading is high with inner cells from 16-cell embryos (56 %) and 32-cell embryos (62%) and isolated inner cell masses (64%). In contrast, the incidence of spreading of 1/8 blastomeres is low over outer cells from 16-cell embryos (26%) and 32-cell embryos (13%). Blastomeres from 8-cell embryos do not spread over unfertilized 1-cell eggs, 1/2 or 1/4 cells or trophectoderm cells contaminating isolated ICMs. When 1/8 cells are aggregated in pairs they flatten on one another (equal spreading) as occurs at compaction in whole 8-cell embryos. However, if 1/8 is allowed to divide to 2/16 in culture one of the cells engulfs the other (51-62/ pairs). Based on the ideas of Holtfreter (1943) and Steinberg (1964,1978) these results are interpreted to indicate an increase in adhesiveness at the 8-cell stage as well as cytoskeletal mobilization. Following the 8-cell stage there is an increase in adhesiveness of inside cells while the outside cells decrease in adhesiveness. The difference in adhesiveness between inside and outside cells in late morulae is probably central to the divergent differentiation of (inner) ICM and (outer) trophectoderm cell populations.

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 101-121
Author(s):  
Hester P. M. Pratt

The preimplantation mouse blastocyst consists of two differentiated tissues, the trophectoderm (a structurally and functionally polarized epithelium) and the inner cell mass. The divergence of these two cell types can be traced back to a contact dependent polarization of the surface and cytoplasm at the 8-cell stage. Membrane/cytocortical organization during this preimplantation period has been studied using freeze fracture in conjunction with the sterol-binding antibiotic filipin in an attempt to discern the molecular basis and origin of these surface asymmetries. The distribution of filipin reactivity within the different membrane domains showed that the surface polarity exhibited by trophectoderm and by blastomeres of the 8-cell stage is underlain by a heterogeneity in molecular organization of the membrane/cytocortex which may originate prior to the appearance of any overt surface polarity. The results are discussed in terms of the likely basis of this membrane/cytocortical asymmetry, its probable origins and the use of the preimplantation mouse embryo as a model system for studying the assembly of a polarized epithelium.


Development ◽  
1979 ◽  
Vol 54 (1) ◽  
pp. 241-261
Author(s):  
M. H. Johnson ◽  
J. Chakraborty ◽  
A. H. Handyside ◽  
K. Willison ◽  
P. Stern

A rabbit antiserum to a mouse embryonal carcinoma cell line blocks compaction of cleaving mouseembryos. Cell division is not affected up to the 32-cell stage but intracellular junctions fail to develop. Removal of the antibody at this stage permits compaction to occur and a normal blastocyst develops. Prolonged decompaction beyond the 32-cell embryo results in an increasing proportion of malformed blastocysts in which trophectodermal cells predominate and functional inner cell mass (ICM) cells are reduced or absent. The relationship of compaction to the generation of ICM and trophectoderm lineages in the intact embryo is discussed.


1985 ◽  
Vol 100 (1) ◽  
pp. 333-336 ◽  
Author(s):  
J S Sobel ◽  
M A Alliegro

The mouse blastocyst expresses a 240,000-mol-wt polypeptide that cross-reacts with antibody to avian erythrocyte alpha-spectrin. Immunofluorescence localization showed striking changes in the distribution of the putative embryonic spectrin during preimplantation and early postimplantation development. There was no detectable spectrin in either the unfertilized or fertilized egg. The first positive reaction was observed in the early 2-cell stage when a bright band of fluorescence delimited the region of cell-cell contact. The blastomeres subsequently developed continuous cortical layers of spectrin and this distribution was maintained throughout the cleavage stages. A significant reduction in fluorescence intensity occurred before implantation in the apical region of the mural trophoblast and the trophoblast outgrowths developed linear arrays of spectrin spots that were oriented in the direction of spreading. In contrast to the alterations that take place in the periphery of the embryo, spectrin was consistently present in the cortical cytoplasm underlying regions of contact between the blastomeres and between cells of the inner cell mass. The results suggest a possible role for spectrin in cell-cell interactions during early development.


Development ◽  
1976 ◽  
Vol 35 (1) ◽  
pp. 59-72
Author(s):  
Audrey L. Muggleton-Harris ◽  
Martin H. Johnson

The nature and distribution of surface alloantigens on preimplantation mouse embryos has been examined by immunofluorescence. Non-H-2 alloantigens were detected at allstages examined, from the 2-cell to the 4½-day blastocyst. Cleaving blastomeres, inner cell mass cells and cells of the primary trophectoderm were all positive. In F1 embryos maternalnon-H-2 alloantigens were detectable at all stages, whereas paternal antigens first became evident at the 6- to 8-cell stage. No convincing evidence of the presence of alloantigens associated with the H-2 haplotype was found at any stage or on any cell type, suggesting that if these antigens are present they are in low quantity or are masked.


Development ◽  
1978 ◽  
Vol 48 (1) ◽  
pp. 53-72
Author(s):  
C. F. Graham ◽  
Z. A. Deussen

The cell lineage of the mouse was studied from the 2-cell stage to the blastocyst. Lineage to the 8-cell stage was followed under the microscope. Each cell from the 2-cell stage divided to form two daughter cells which remained attached. Subsequently, these two daughters each produced two descendants; one of these descendants regularly lay deep in the structure of the embryo while the other was peripheral. Lineage to the blastocyst was followed by injecting oil drops into cells at the 8-cell stage, and then following the segregation of these drops into the inner cell mass and trophectoderm. Between the 8-cell stage and the blastocyst, the deep cells contributed more frequently to the inner cell mass than did the peripheral cells.


Development ◽  
1994 ◽  
Vol 120 (11) ◽  
pp. 3289-3299 ◽  
Author(s):  
C. Gueth-Hallonet ◽  
A. Santa-Maria ◽  
P. Verroust ◽  
B. Maro

During preimplantation development of the mouse embryo, a layer of outer cells differentiates into a perfect epithelium, the trophectoderm. The divergence between the trophectoderm and the inner cell mass takes place from the 8-cell stage to the 64-cell stage and precedes their commitment at the blastocyst stage. In this work, we have investigated the expression of gp330, a 330 × 10(3) M(r) glycoprotein found in clathrin-coated areas of the plasma membrane of some epithelial cells characterized by a high level of endocytic activity. Our results show that gp330 is first synthesized in 16-cell stage embryos and that its appearance is restricted to outer cells until the blastocyst stage. Furthermore, its expression is repressed in inner cells at a post-transcriptional level, probably through the development of extensive cell-cell contacts.


Development ◽  
1988 ◽  
Vol 104 (2) ◽  
pp. 219-234
Author(s):  
J.A. Emerson

The distribution of the cytokeratin network in the intact preimplantation mouse embryo and the role of cytokeratin filaments in trophectoderm differentiation were investigated by means of whole-mount indirect immunofluorescence microscopy and microinjection of anti-cytokeratin antibody. Assembled cytokeratin filaments were detected in some blastomeres as early as the compacted 8-cell stage. The incidence and organization of cytokeratin filaments increased during the morula stage, although individual blastomeres varied in their content of assembled filaments. At the blastocyst stage, each trophectoderm cell contained an intricate network of cytokeratin filaments, and examination of sectioned blastocysts confirmed that extensive arrays of cytokeratin filaments were restricted to cells of the trophectoderm. Microinjection of anticytokeratin antibody into individual mural trophectoderm cells of expanded blastocysts resulted in a dramatic rearrangement of the cytokeratin network in these cells. Moreover, antibody injection into 2-cell embryos inhibited assembly of the cytokeratin network during the next two days of development. Despite this disruption of cytokeratin assembly, the injected embryos compacted and developed into blastocysts with normal morphology and nuclear numbers. These results suggest that formation of an elaborate cytokeratin network in preimplantation mouse embryos is unnecessary for the initial stages of trophectoderm differentiation resulting in blastocyst formation.


Zygote ◽  
2000 ◽  
Vol 8 (3) ◽  
pp. 235-243 ◽  
Author(s):  
Pin-chi Tang ◽  
John D. West

Studies with intact preimplantation mouse embryos and some types of chimaeric aggregates have shown that the most advanced cells are preferentially allocated to the inner cell mass (ICM) rather than the trophectoderm. Thus, differences between 4-cell and 8-cell stage embryos could contribute to the tendency for tetraploid cells to colonise the trophectoderm more readily than the ICM in 4-cell tetraploid[harr ]8 cell diploid chimaeras. The aim of the present study was to test whether 4-cell stage embryos in 4-cell diploid[harr ]8-cell diploid aggregates contributed equally to all lineages present in the E12.5 conceptus. These chimaeras were compared with those produced from standard aggregates of two whole 8-cell embryos and aggregates of half an 8-cell embryo with a whole 8-cell embryo. As expected, the overall contribution of 4-cell embryos was lower than that of 8-cell embryos and similar to that of half 8-cell stage embryos. In the 4-cell[harr ]8-cell chimaeras the 4-cell stage embryos did not contribute more to the trophectoderm than the ICM derivatives. Thus, differences between 4-cell and 8-cell embryos cannot explain the restricted tissue distribution of tetraploid cells previously reported for 4-cell tetraploid[harr ]8-cell diploid chimaeras. It is suggested that cells from the more advanced embryo are more likely to contribute to the ICM but, for technical reasons, are prevented from doing so in simple aggregates of equal numbers of whole 4-cell and whole 8-cell stage embryos.


1982 ◽  
Vol 35 (2) ◽  
pp. 187 ◽  
Author(s):  
GM Harlow ◽  
P Quinn

The culture conditions for the development in vitro of (C57BL/6 X CBA) F2 hybrid two-cell embryos to the blastocyst stage have been optimized. Commercially available pre-sterile disposable plastic culture dishes supported more reliable development than re-usable washed glass tubes. The presence of an oil layer reduced the variability in development. An average of 85 % of blastocysts developed from hybrid two-cell embryos cultured in drops of Whitten's medium under oil in plastic culture dishes in an atmosphere of 5% O2 : 5% CO2 : 90% N2 ? The time taken for the total cell number to double in embryos developing in vivo was 10 h, and in cultured embryos 17 h. Embryos cultured in vitro from the two-cell stage to blastocyst stage were retarded by 18-24 h in comparison with those remaining in vivo. Day-4 blastocysts in vivo contained 25-70 cells (mean 50) with 7-28 (mean 16) of these in the inner cell mass. Cultured blastocysts contained 19-73 cells (mean 44) with 8-34 (mean 19) of these in the inner cell mass. In the uterine environment, inner-cell-mass blastomeres divided at a faster rate than trophectoderm blastomeres and it is suggested that a long cell cycle is associated with terminal differentiation. Although cultured blastocysts and inner cell masses contained the same number of cells as blastocysts and inner cell masses in vivo, the rate of cell division in cultured inner cell masses was markedly reduced.


Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 83-89
Author(s):  
Lincoln V. Johnson ◽  
Patricia G. Calarco ◽  
Margaret L. Siebert

Alkaline phosphatase (AP) activity has been assayed in frozen sections of preimplantation mouse embryos by an azo-dye cytochemical method. The results indicate that during preimplantation mouse development AP activity is first expressed between the 8- and 16-cell stages and develops in all cells by the late morula stage. During blastocyst formation AP activity is lost or greatly reduced in trophoblast cells while activity is maintained in the inner cell mass.


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