When was the mammalian egg discovered

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This research used resources of the Advanced Photon Source, a U. Argonne National Laboratory seeks solutions to pressing national problems in science and technology. By Matthew Davenport and Andre Salles. Bioethics etymologically "ethics of life" offers an opportunity for dialogue between biological sciences and the humanities philosophy, ethics, anthropology to be able to address from an inter-disciplinary perspective the situations generated from biological knowledge that have social impacts.

In this respect, Professor Claudio Barros encouraged this inter-disciplinary dialogue in our country to address the problem of when human life begins. Although the biological sciences have unarguably demonstrated that the development of a new human being begins with fertilization, several countries have questioned that the life of an embryo before implantation be considered that of a new human being, deserving of respect as such.

For example, in the countries of the European Community it is considered that legally the human nature of the embryo is acquired at 14 days, given that at this point the nervous system of the embryo begins to manifest itself and the indivisibility of the embryo begins. For these countries, the human embryo is only a subject that merits respect at day Prior to that, the embryo is an "object" or "thing" called a "pre-embryo and consequently susceptible to manipulation, which supports therapeutic cloning through the use of stem cells.

There is no doubt that the embryo is implanted on day 7 and that it manifest the impossibility of division and of expressing its nervous system on day These are only phases of a continued and ordered sequencing succession of biological events that began in the moment of fertilization. Consequently, these limits are arbitrary Damschen et al. And with this, the use and destruction of pre-implantation human embryos has been justified. Life is a continuum, because of which if the life of a human being begins in the moment of fertilization, with the zygote "that houses all the necessary instructions for building a human body" Lodish et al.

After a long road, the questions raised by the Greeks about the beginning of life and the process of generation of a new individual have taken us to clarifying life begins without any doubt in the moment of fertilization.

The direct observation of this process by embryologists at the cellular level has been corroborated with fascinating discoveries at the molecular, genetic and epigenetic levels. We all begin, as Haeckel said "as a simple cell", but a cell that is a true organism that from its initial moment upon the fusing of the membranes of the spermatozoid and the ovum begins a coordinated activity clearly oriented to a determined development.

Both the RNA inherited from the mother and the genes received from the father are activated through complex epigenetic mechanisms. From its first stages, the cells show a determined direction in a rich balance between regulation and plasticity. From the earliest stages, the generated child begins a rich exchange of signals with the mother that through an admirable coordination allows for the zygote's implantation in the mother's womb. Considering the panorama of human development, we add to the statement of Lodish and colleagues that this is not only an amazing feat, but also a wonderful and complex one.

We believe that in these words we find the passion and dedication of Claudio Barros for research in this field.

At the opening, we stated that this issue has practical implications for the use and destruction of embryos in their first stage of development for therapeutic purposes, which is a question that has generated intense debates. Countries have taken different positions in relation to the legal status of the embryo.

The Constitution in Chile protects all human beings without discrimination, including the unborn. In the Genome Law was passed, which deals with research into human beings and cloning.

The Law specifies that the life and integrity of every human being must be protected from the moment of conception. Zygote Alonso Miguel. Madrid Ed. Sem Reprod Med v Organologische Studien. Nabu Press. The moral case or ANT-derived plutipotent stem cell lines. Natl Cathol Bioeth Quarterly 6: J Exp Zool.

Early steps of sperm-egg interactions during mammalian fertilization. Cell Biol Int. Behavior of the gamete membranes during sperm entry into the mammalian egg. J Cell Biol. Rev Med Chile Newport bei Betrachiern und Dr. Barry bei den kanichen behaupteten eindringens der Spermatozoiden in das Ei. PLoS Biol. Hum Reprod Update Louis: Mosby.

A reply to B. Smith and B. Brogaard on the beginning of human individuals. J Med Philos Human Reprod , [ Links ]. Scan Electron Microsc Nat Cell Biol. Am J Med Genet , [ Links ]. The acrosomal region and the acrosome reaction in sperm of the golden hamster. Biol Reprod. Adv Exp Med Biol Sunderland Ma : Sinauer Associates, Inc, pp J Law Med Ethics.

Nat Rev Mol Cell Biol Embryo-maternal signaling: how the embryo starts talking to its mother to accomplish implantation. Reprod Biomed Online , [ Links ]. J Reprod Dev Nature Human Embryology. New York: Churchill-Livingston. Tomus I. Homiae: Salvius. New York, NY, W. Factors controlling blastocyst implantation. Reprod Biomed Online Philadelphia: W. Saunders Co. Phil Trans Roy Soc Genetic Determinism. London: Channel 4 Books, Chang, Min Chueh. Cole, Robin J. Edwards, and John Paul.

Corea, Gena. Edwards, Robert G. Alberda, R. Gan, and H. Vemer, 7— Nashville: Parthenon, London: Hutchinson, Jones, Howard W. Vemer, 25— Maienschein, Jane. Whose View of Life? Embryos, Cloning, and Stem Cells.

Pincus, Gregory. The Eggs of Mammals. New York: The Macmillan Company, Pincus, Gregory and E. Printer-friendly version PDF version. Please log in with your institutional or personal account if you should have access to this content through either of these.

Showing a limited preview of this publication:. Abstract The zona pellucida, a glycoprotein matrix surrounding the mammalian oocyte, hardens after intrusion of the first spermatozoon, thus protecting the embryo until implantation and preventing multiple fertilizations polyspermy.

Keywords: cystatins ; fertilization ; metzincins ; polyspermy ; proteolytic network ; zona pellucida. Received: Accepted: Published Online: Published in Print: Mammalian gamete fusion depends on the inhibition of ovastacin by fetuin-B. Biological Chemistry , 10 , Biological Chemistry, Vol. Biological Chemistry. Copy to clipboard. Log in Register. Volume Issue This issue. All issues. Articles in the same Issue Frontmatter. Highlight: The protease web. Angiotensin-I converting enzyme ACE : structure, biological roles, and molecular basis for chloride ion dependence.

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