Saccharide structures of the mouse embryo during the first eight days of development. Inferences from immunocytochemical studies using monoclonal antibodies in conjunction with glycosidases.

Monoclonal anti-carbohydrate antibodies have been used in conjunction with glycosidases in immunofluorescence studies to derive information about the structures and in situ distribution of saccharides of the mouse embryo during the first 8 days of development. The salient findings are as follows: Branched poly-N-acetyllactosamine sequences of I-antigen type are detectable from the first day onwards and are widely distributed in cells of the endoderm, ectoderm and mesoderm. Linear poly-N-acetyllactosamine sequences of i-antigen type are detectable from the fifth day onwards in cells of all three lineages, but have a more restricted distribution than the sequences of I-type. Poly-N-acetyllactosamine sequences that are susceptible to digestion with endo-beta-galactosidase are the main carriers of the SSEA-1, C14 and the blood group B-like antigens, which have the following structures (Formula; see text) and are found in endoderm and ectoderm but not in mesoderm cells. In the trophoblast however, these antigens are borne on saccharides that are resistant to endo-beta-galactosidase. A proportion of the poly-N-acetyllactosamine structures in the endoderm and the ectoderm of the 5- and 6-day embryos may contain the following novel structures: (Formula; see text) in which antigenicities of SSEA-1 and C14 determinants are masked. There are several types of sialyl-oligosaccharides: those reactive with anti-Gd, which has a specificity for NeuAc alpha 2-3Gal beta 1-4GlcNAc sequence in the extraembryonic mesoderm and the heart; those reactive with anti-Pr2 but not with anti-Gd, which may correspond to other N-acetylneuraminic acid containing sequences such as NeuAc alpha 2-3Gal beta 1-3GalNAc or NeuAc alpha 2-6Gal in preimplantation embryos and in the yolk sac, neural ectoderm and mesenchyme of the 8-day embryo; those with other sialic acid forms or linkages that do not react with anti-Gd and Pr2; among these are sialosyl-i sequences in the extraembryonic ectoderm, and sialosyl-I sequences in most cell types during the first 8 days. The latter are the main poly-N-acetyllactosamine structures in the neural ectoderm of the 8-day embryo. The sequence Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc/GlcNAc, or cross-reactive structures, which bind FC10.2 antibody occur in the extraembryonic endoderm and yolk sac. The roles of specific carbohydrate structures as receptors during embryonic development and cell growth are important topics of current research.(ABSTRACT TRUNCATED AT 400 WORDS)