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In the interspecific hybridizations Phaseolus polyanthus (or Phaseolus coccineus cv.) x Phaseolus vulgaris, embryo abortion appears in 60 per cent of studied cases at globular stage, 4 to 8 days after pollination according to the crosses. From a bibliographic review, a histological study of the Phaseolus ovule development brings to the fore the major part of integuments and nucellus in the nutrition of the embryo and the albumen. The monitoring of Phaseolus ovular structure modifications allows the identification of nutriments transfer modes from zygote up to cotyledon stage. Comparison between the P. polyanthus female parent and P. polyanthus x P. vulgaris hybrid ovule development, enables structures responsible for disturbances in the feeding of the hybrid embryo to be defined. These are located essentially in the nucellus and the endothelium. The embryo rescue relies on the existence of a suitable in vitro culture technique. This technique has been developed for the early heart-s haped embryos of P. vulgaris, and is efficient for P. coccineus, P. polyanthus and for the intraspecific or interspecific hybrids which are easiest to obtain. Improving this technique is being examined to enable the regeneration of plants from globular embryos. An in vitro medium with a composition which varies over a period of time and which meets the globular embryo osmotic and nutritive needs, has been developed. The continual variation of the embryo nutrition during its in vitro development is achieved by a system, where two gelified media come into contact. In this setup, a diffusion of the components occurs from the richer to the poorer medium, until the concentrations reach a steady state. A study of the nutritional needs of the globular and heart shaped-embryos of P. vulgaris, was carried out to determine the role of plant growth regulators in embryo growth and morphological evolution. The contribution of magnesium, iron and calcium in the normal differentiation of globular emb ryos has been emphasized. The reduced nitrogen and carbon hydrate sources have been examined. Glutamin and asparagin appeared to be the preferential way for nitrogen assimilation. According to their concentrations, sucrose, maltose and glucose exert a different impact on globular embryos growth and development. For each studied embryonic stage globular and early heart-shaped, an improved medium has been suggested. The application of a brief dark period at the start of the culture followed by a light period, besides using a design that ensures the variation of the medium composition and which integrates the previously formulated inferences, enables 60 per cent of cultivated globular embryos to reach the cotyledon stage and 13 per cent to germinate. Interactions between on the one hand, the light conditions and on the other, the osmotic pressure and the hormonal composition are highlighted. Thanks to preliminary studies concerning the pre-acclimatization medium composition, the use of ho rmonal components will not be needed in the future.

Phaseolus --- Phaseolus --- Embryonic development --- Embryonic development --- in vitro. --- in vitro

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chickens --- chickens --- Embryonic development --- Embryonic development --- Central nervous system --- Central nervous system --- Pituitary hormones --- Pituitary hormones

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Swine --- Swine --- Embryo transfer --- Embryo transfer --- Embryonic development --- Embryonic development --- Embryo culture --- Embryo culture

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Dairy cows --- Dairy cows --- Ova --- Ova --- Embryonic development --- Embryonic development --- Embryo culture --- Embryo culture --- Zygotes --- Zygotes --- Enbryon animal --- Enbryon animal

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Carrots --- Carrots --- Arabidopsis --- Arabidopsis --- Chitin --- Chitin --- Plant protein --- Plant protein --- Embryonic development --- Embryonic development --- plant growth substances --- plant growth substances --- Somatic embryos --- Somatic embryos