Life and Medical Sciences
Cell & Developmental Biology
Wiley InterScience Backfile Collection 1832-2000
Arginine, cystine, histidine, leucine and threonine were needed for outgrowth of the mouse blastocyst in vitro. Omission of lysine, methionine, phenylalanine, tryptophane and tyrosine from the culture medium markedly reduced blastocyst outgrowth, but did not inhibit it completely; while omission of isolecine and valine reduced the extent of outgrowth only slightly. Blastocysts kept for seven days in a free-floating condition by omitting arginine and leucine from the medium, grew out when these amino acids were added. Such behavior may be analogous to delayed implantation in utero and suggests that the free amino acid content of the uterus could be an important factor in the control of implantation. Blastocysts delayed from implanting in the uterus by ovariectomy were activated to outgrowth in a complete medium, but the intracellular changes associated with outgrowth occurred more slowly than in undelayed blastocysts.
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