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Lo statuto biologico e ontologico dell’embrione

ROMA, lunedì, 4 febbraio 2008 ( ZENIT.org ).- Pubblichiamo di seguito per la rubrica di Bioetica l'intervento del dottor Renzo Puccetti, Specialista in Medicina Interna e Segretario del Comitato “Scienza & Vita” di Pisa-Livorno.
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Salve, complimenti per la vostra ottima rubrica scientifica e culturale. Sono a professor of religion, but right now I'm doing an internship to get an authorization in history and philosophy (I graduated in philosophy), and as I will have to address the issue if the embryo is an individual / person in the context of 'epistemology who are studying at school (a high school), I wanted to have a scientific-biological explanations to justify the absolute prohibition of manipulating the sanctity of life. Thanks and see you soon. LP

I thank the reader for an application that allows you to provide any relevant information to frame the question of the embryo. The terms in which the question is posed, beyond the intentions of the writer, are likely to repeat a fallacy: first determine what is the action to be taken and then find the reasons for it. The question concerning the biological status of the embryo and ontological challenges those who draw near to ultimate measure with the truth of the embryo. In the medical-scientific privileged and generally fought to get to the truth is that Thomistic correspondista (adequatio rei et intellectus). It is a policy which recognizes things in the presence of an objective truth that is understandable by human reason, which, in turn, is shaped so as to be open to it and accept it.
Of course, sometimes in the medical field is also used a pragmatic criterion that identifies as true what works, but in this case the search for a more complete knowledge of the truth is always in the background as the ultimate aspiration. Specifically, there seems to be defined as a prior ontological status of the embryo, that embryo understood as to understand the nature and essence and should assess the moral behavior directed toward him. As noted Professor Pessina, use the word "person" in reference to the embryo leads to very often a complication of the debate, as the term person has taken in common language, in addition to the original descriptive meaning, also a connotation of values. For this reason it is easier to submit to verify the following hypothesis: the embryo from the moment of fertilization is a living human individual?
Within forensic DNA analysis is used as a conclusive criterion to identify the individual author or the victim of a particular crime, or parenting a child, for the identification of the individual. The moment of syngamy, ie, membrane fusion of two gametes, is the time where it is possible to identify a novel gene diploid, that is not traceable to that of any other being on earth. Before karyogamy (fusion of gametes of parental gene pools), this heritage has not yet rearranged into a structure identificabile anatomicamente, ma lo è già in termini funzionali. I DNA materno e paterno attivati, benché non ancora uniti fisicamente, colloquiano (1) e operano in maniera coordinata guidando il processo di avvicinamento dei pronuclei genitoriali e la formazione del fuso mitotico, prodromico alla prima divisione cellulare (2). Ulteriori conferme giungono dagli studi che hanno mostrato come gli assi embrionali sono definiti già nei minuti ed ore che seguono la singamia (3) e non, come precedentemente ritenuto, al momento della stria primitiva, elemento questo che induceva qualcuno a pensare l’embrione nei primi 14 giorni come ad un grumo di cellule.
In base alle evidenze più recenti, la posizione del secondo globulo polare, il punto di entrata dello spermatozoo e la forma dell’ovocita sono in grado d’influenzare l’asse della prima divisione cellulare che, a sua volta, determina il destino delle cellule figlie in cellule progenitrici dell’embrione e cellule progenitrici dei tessuti non embrionali (3). Una delle argomentazioni impiegate per porre in discussione in maniera alquanto surrettizia la dignità dell’embrione è quella secondo cui l’embrione non sarebbe in grado di entrare in relazione con la madre, almeno fino alla fase dell’impianto nella parete endometriale. Si tratta di un’argomentazione difficilmente sostenibile.
Dal punto di vista biologico la fase pre-impiantatoria si caratterizza per un intenso colloquio biochimico maternal fetal (crosstalk), which assists the production of embryonic factors (Early Pregnancy Factor, Leukemia Inhibitory Factor, Perimplantation Factor) in which the mother responds with anatomical and functional changes and providing energy substrates through the tubal fluids that support anaerobic metabolism of 'in the pre-implantation embryo. Furthermore, the genomic imprinting (epigenetic inactivation of one allele of a gene underlying the phenomenon monoallelica expression) is able to influence both the maternal fetal relationship behaviors and attitudes post-natal (sucking, thermoregulation, pubertal development) (4).
These considerations can also add comments derived in particular by Dr. Diana Bianchi has shown the presence of a true "mobile traffic" in which cells derived from embryonic stem cells are placed in various organs of the mother and will persist for decades even restorative function (5, 6, 7 ). Thus it is not unreasonable, the sentence of an editorial in the British Medical Journal: "The embryo is not passive but an active orchestrator of its plant and its destiny" (8). To capture these considerations in view of the reality of the static specific aspects you can add a look that captures the dynamism verifies the embryonic nature. Because the observation of nature tumorale di poche cellule in un preparato citologico è universalmente accettato che la condotta clinica si disponga considerando cosa sarà di quelle cellule una volta progredite nel loro ciclo vitale, mentre dovrebbe essere illogico affermare la natura d’individuo umano mortale dell’embrione dalla sua osservazione al microscopio e soprattutto non agire pensando a come sarà una volta che abbia completato il suo sviluppo? Paradossalmente è possibile imbattersi in esimi studiosi che pretendono di mantenere separati il piano scientifico da quello etico introducendo nel discorso scientifico considerazioni ad esso assolutamente estranee.
Affermare che lo zigote (embrione unicellulare) e la morula (stadio embrionale di otto cellule) siano «progetti of the individual "(9) destined to die because a high percentage or twinship is a potential for non-logical sense. The embryo is already individual shares with a destiny of any living individual mortality, spontaneous or provoked. Then perhaps we should say that those condemned to death, the soldiers in the trenches and all those about to die because people are not used in a high percentage of imminent death? Did the twins still get two people, instead of two individuals do not? It also seems reasonable not to deny the identity of individual sheep to the sheep that provided the somatic cell from which Dolly was derived on the basis of the potential cloned. A volta riconosciuto quindi che «dal punto di vista biologico non c’è in sostanza nessuna discontinuità dal concepimento alla nascita» (9) l’ipotesi di «porre degli spartiacque» sulla base di «una convenzione» (9) modificabile non è innocente, ma introduce nel percorso conoscitivo un’evidente volontà manipolativa, in cui la realtà dell’altro (in questo caso dell’embrione) è funzione dell’utile che ne può derivare. Concetto pericoloso, anzi pericolosissimo quello di stabilire per convenzione quando l’altro sia intangibile, una volta comunque accertata la sua natura di individuo umano vivente. È stato fatto in passato e quando la memoria non si era ancora dissolved the doctors had sworn that they would not have done anymore. But those doctors are now dead, other generations have followed the law and the fall of civilization described by Solon seems to want to continue to draw its trajectory. Determined that since the embryo after fertilization is a human individual living raises the moral question: "All individuals are entitled to living humans that their life is respected?".
We believe that we can only answer in the affirmative, as the primary good of human life and a necessary condition for the enjoyment of secondary assets. The very concept of self-defense is not an exception to the principle of inviolability of human life, since does not indicate the killing self-defense, but the killing in defense (10). Every time we introduce the minimum opening between the biological concept of living human individual and the moral person, without realizing it, even with the noblest intentions, we open the door to the demon of arbitrariness. This is a very real threat that the man to defend themselves from lions builds a stick by sawing off the branch on which he sits protected from the beasts. Romano Guardini writes in 1949: "Actions ethically wrong, even if they seem useful, in the end lead to ruin. Lying can bring a benefit, ten, a hundred times, in the end it crushes upon which the life in his own inner life than the di se stessi, nel rapporto con gli altri la fiducia» (11).
Si tratta di una prospettiva consonante con quella proposta trent’anni più tardi dal filosofo ebreo tedesco Hans Jonas, fuggito dalla dittatura nazista la cui madre fu tra le vittime di Auschwitz: «Si dovranno apprendere nuovamente il rispetto e l’orrore per tutelarci dagli sbandamenti del nostro potere. Soltanto il rispetto, rivelandoci “qualcosa di sacro”, cioè d’inviolabile in qualsiasi circostanza ci preserverà anche dal profanare il presente in vista del futuro, dal voler comprare quest’ultimo al prezzo del primo. Un’eredità degradata coinvolgerebbe nel degrado anche gli eredi. Conservare intatta quell’eredità through the perils of the times, indeed, against the act of man, not a utopian view, but the end, not so modest, the responsibility for the future of man "(12).
References:
1. Ostermeier GC, Miller D, Huntriss JD, Diamond MP, Krawetz SA. Reproductive biology: delivering spermatozoan RNA to the oocyte. Nature. 2004 May 13, 429 (6988): 154.
2. Pontifical Academy for Life. The human preimplantation embryo in the ITS phase. Scientific Aspects and bioethical considerations. http://www.academiavita.org/english/Documenti/testo/embrio/vol_embr_ingl.pdf
3. H. Pearson Your destiny, from day one. Nature. 2002 Jul 4; 418 (6893) :14-5.
4. Isles AR, Holland AJ. Imprinted genes and mother—offspring interactions. Early Human Development (2005) 81, 73-77.
5. Bianchi DW, Fisk NM. Fetomaternal cell trafficking and the stem cell debate: gender matters. JAMA. 2007; 297(13):1489-91.
6. Bianchi DW, Romero R. Biological implications of bi-directional fetomaternal cell traffic: a summary of a National Institute of Child Health and Human Development-sponsored conference. J Matern Fetal Neonatal Med. 2003 Aug;14(2):123-9.
7. Johnson KL, Bianchi DW. Fetal cells in maternal tissue following pregnancy: what are the consequences? Hum Reprod Update. 2004 Nov-Dec;10(6):497-502.
8. Horne AW, White JO, Lalani EN. The endometrium and embryo implantation. A receptive endometrium depends on hormonal Influences More Than. BMJ. 25 November 2000, 321 (7272) :1301-2.
9. Edoardo Boncinelli. Embryos. There is no time X. Corriere della Sera, 26.01.2005. http://www.puntoincontro.org/Animazione/Incontri2005/05-Boncinelli1.htm
10. St. Thomas Aquinas, Summa Theologiae, II-II, q.64, a. 7.
11. Romano Guardini. The right to life before birth. And Morcelliana, Brescia, 2005.
12. Hans Jonas. The principle of responsibility. Einaudi, Torino, 1990.