
%0 Journal Article
%A Mishra, Archana 
%A Seshagiri, P. B. 
%T Successful development <emph type="2">in vitro</emph> of hamster 8-cell embryos to &#8216;zona-escaped&#8217; and attached blastocysts: assessment of quality and trophoblast outgrowth
%J Reproduction, Fertility and Development
%D 1999/06/17
%V 10
%N 5
%P 413-420
%K attachment, blastocyst development, hamster, hatching, zona lysis.
%R https://doi.org/10.1071/RD98100
%U https://www.publish.csiro.au/paper/RD98100 
%X The peri-implantation development involves zona escape (hatching) of blastocysts and their attachment and proliferation. These events are difficult to studyin vivo, so in this study hamster 8-cell embryos were cultured through the hatched and attached blastocyst stages using different formulations of hamster embryo culture medium (HECM)-2. Supplementation of succinate, amino acids, vitamins (inositol, pantothenate, choline chloride) and bovine serum albumin (BSA) to HECM-2 supported 100% development of &#8216;zona-escaped&#8217; blastocysts. In this medium (designated as hatching, i.e. HECM-2h) all blastocysts invariably deflated and escaped from focally lysed zonae, which underwent complete dissolution. In their presence, pre-morula stage embryos also escaped from zonae. Omission of BSA from HECM-2h failed to support zona escape whereas that of vitamins reduced zona escape (34.0% 7.0). Blastocysts with the potential to undergo zona escape in HECM-2h were of high quality as they had a higher mean cell number (MCN) than the MCN of those developing in BSA-free HECM-2h (35.2 1.6 v. 24.3 1.1). Cell allocation (i.e. trophectoderm to inner cell mass ratio) in blastocysts remained unaltered in both media (2.6 0.2 v. 2.7 0.2). Supplementation of 10% bovine fetal serum (BFS) to HECM-2h was detrimental to the development of blastocysts (22.3% 7.4) and none of them underwent zona escape. Interestingly, BFS was required either as a supplement to the medium or as a coating on dishes for azonal blastocysts to attach (&#x2265;70%) and exhibit trophoblast (TB) outgrowth (30.3 &#215; 103 2.9 &#215; 103 &#181;m2 at 48 h). These results show that HECM-2h supports maximal development of zona-escaped blastocysts with the potential to attach and exhibit TB outgrowth, and there is a developmental stage-specific requirement for serum during peri-attachment in hamster development. 
