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C. A. FINN and J. C. S. BREDL

Summary.

The influence of actinomycin D on the implantation of blastocysts has been studied in mice. The early stages of implantation, the Pontamine sky blue reaction and stromal oedema take place normally and the blastocyst is stimulated to develop. Decidualization, however, is delayed and the degeneration of the uterine epithelium around the blastocyst is inhibited, suggesting that the latter is dependent on DNA-directed messenger RNA synthesis whereas the initial implantation changes and activation of the blastocyst are not.

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C. A. Finn and J. C. S. Bredl

The administration of actinomycin D to pregnant mice before the zygote has started to implant does not prevent the early stages of the implantation reaction but does delay, for a period of about 30 h, differentiation of the endometrial stromal cells into decidual cells (Finn & Martin, 1972; Finn & Bredl, 1973). During the period of delay vascular permeability is increased and oedema fluid collects in the stroma. An inhibitory effect of actinomycin D on decidualization has also been demonstrated in the rat (Burin & Sartor, 1965; Sananès & Psychoyos, 1970).

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ROSEMARY M. POLLARD, J. C. S. BREDL and C. A. FINN

The antibiotic, actinomycin D, prevents the normal implantation of blastocysts (Psychoyos, 1967), and delays the development of the decidual cell reaction (Finn & Martin, 1972), probably due to an effect on RNA synthesis. The first stage of implantation, i.e. increased vascular permeability, as shown by the extravasation of the dye Pontamine Sky Blue, takes place normally, and the growth and development of the blastocyst continues. The endometrial epithelium, however, does not degenerate and decidualization of the stromal cells fails to occur at the normal time, with the result that the blastocyst is surrounded by an intact epithelium (Finn & Bredl, 1973).

The object of the present work was to investigate, with the electron microscope, the effect of the drug on the initial attachment of the trophoblast to the uterine epithelium in pregnant mice (the attachment reaction; Nilsson, 1966), and on the hormone-induced closure of the uterine lumen in ovariectomized mice.

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CE Green, J Bredl, WV Holt, PF Watson and A Fazeli

After mating, mammalian spermatozoa are transported to the lower oviductal isthmus. Spermatozoa are sequestered at the isthmus by attaching and interacting with oviductal epithelial cells, hence forming a sperm reservoir. In several mammalian species, specific carbohydrates mediate sperm-oviductal epithelial cell binding. A quantitative in vitro free cell bioassay was developed to investigate the involvement of carbohydrate recognition in pig sperm-oviductal epithelial cell interactions. This assay was validated. The sensitivity of the assay was such that it was possible to discriminate between different sperm concentrations and sperm-oviductal epithelial cell co-incubation periods, spermatozoa with damaged plasma membranes and epithelial cells of non-reproductive origin. Optimal conditions were used to incubate spermatozoa and oviductal epithelial cells in the presence of six hexose sugars at concentrations of 0, 2, 10 and 50 mmol l(-1). A significant (P < or = 0.05) reduction in the binding of spermatozoa to the oviductal epithelium was detected with 2, 10 and 50 mmol maltose l(-1), 50 mmol lactose l(-1) and 50 mmol mannose l(-1). These findings support the hypothesis that attachment of pig spermatozoa to oviductal epithelium before fertilization is mediated by carbohydrate recognition.