The occurrence of elongated intercellular bridges in deep cells ofOryzias embryos during blastula and gastrula stages
✍ Scribed by Kageyama, Tetsuo
- Publisher
- John Wiley and Sons
- Year
- 1988
- Tongue
- English
- Weight
- 964 KB
- Volume
- 248
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
The occurrence of an elongated intercellular bridge (IB) connecting a pair of postmitotic cells in the middle of which a midbody intervenes has been reported in several lines of cultured cells and on the surface of embryonic epithelia. Using the cell isolation method, this same structure also was revealed to be present in inner blastomeres of the embryo of Oryzias Zatipes. The IB emerges in the midblastula stage, when cleavage has become asynchronous and deep cells with protruding pseudopodia begin their locomotion through expanding intercellular space. The paired cells interconnected by the IB occupy 7-10% of the total number of deep cells, and some IBs are elongated to as long as 50 p m from the midblastula until the beginning gastrula stage. The IB is produced by incomplete cytokinesis, and it probably elongates itself until it is approximately 5 pm in length. Several lines of evidence suggest that the IB elongates further as sister cells move apart by means of pseudopodia. The fraction of elongated IBs gradually decreases during the gastrula stage, until no IB is observed thereafter. One likely cause of the decrease is that the gastrula has less space for divided cells to separate from each other, preventing the IB from elongating further. Naturally, the maximal and average lengths of the IB decrease as the gastrula stage proceeds.