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Does Personhood Begin at Conception?
Published in Christopher Kaczor, The Ethics of Abortion, 2023
This is a biological question, and we could quote here, page after page, numerous biologists, scientists, and physicians who have provided clear answers to this question. In the interest of space, let's consider only three texts (noted earlier by Lee 1996):The formation, maturation, and meeting of a male and female sex cell are all preliminary to their actual union into a combined cell, or zygote, which definitely marks the beginning of a new individual. This penetration of the ovum by spermatozoon, and the coming together and pooling of their respective nuclei, constitutes the process of fertilization.(Arey 1974, p. 55)the fertilization of an ovum by a sperm. The expression “fertilized ovum” refers to the zygote.(Moore 1983, p. 9)Embryonic life commences with fertilization, and hence the beginning of that process may be taken as the point of departure of stage I.(Larsen 1993, p. 19)
Plant Source Foods
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
The gymnosperms are non-flowering or seed-producing plants such as Cycas, Pinus, Ginkgo in which ovules are not enclosed by any ovary wall; hence they are called naked-seeded plants. In angiosperms or flowering plants, the male sex organs (stamen) and female sex organs (pistil) are borne in a same flower. The anther produces pollen grains (male gametophyte). The pistil consists of an ovary enclosing one to many ovules. Within the ovule is the female gametophyte or embryo sac which contains the egg cell. The angiosperms are divided into two classes: the monocotyledons or monocots (seed with a single cotyledon or one embryonic leaf) and the dicotyledons or dicots (seed having two cotyledons or two embryonic leaves) (2). They range in size from tiny, aquatic Wolffia to tall trees of Eucalyptus (over 100 m). Plants provide us with food, fodder, fuel, medicines, and several other commercially important products (2).
Principles of Pathophysiology of Infertility Assessment and Treatment*
Published in Asim Kurjak, Ultrasound and Infertility, 2020
Joseph G. Schenker, Aby Lewin, Menashe Ben-David
Infertility may be caused by a single or multiple etiological factor(s). It is customary to classify the causes of infertility into the following major groups: Failure of ovulationMechanical factors: including tubal pathology and peritoneal causes that disturb the ovum pick-up mechanism, transport of gametes, fertilization, and early preembryo transportUterine factors: Muellerian duct abnormalities, intrauterine adhesions and uterine tumorsCervical factors: cervical anomalies and impaired cervical mucus secretionMale factors: inadequate or abnormal production, ejaculation, and deposition of spermatozoaEmotional aspects and sexual disturbancesImmunological factorsUnexplained infertilityMultifunctional factors
Human Germline Genome Editing: On the Nature of Our Reasons to Genome Edit
Published in The American Journal of Bioethics, 2022
Douglas and DeVolder’s argument is fascinating and well-made. However, it assumes that it would be ethically defensible to genome edit, and then to proceed to implant, a single, already existing, embryo, which, as I have argued here, is highly unlikely for the foreseeable future. In all likelihood, genome editing will involve creating and editing multiple embryos before selecting the “best child possible.” Moreover, where prospective parents are motivated by a desire to enhance their children rather than to avoid a genetic disorder, which, I have suggested, is a more plausible motivation for the project in the longer term, the decision to genome edit will almost certainly be identity affecting, as a couple (or individual) will usually make it before they have created any embryos and the process itself will, at the very least, alter the timing of conception. This is itself usually sufficient to bring it about that a different sperm fertilizes the ovum, with the consequence that a different person is born (Parfit 1984, 351–352). Thus, if we include the decision to edit in our deliberations about the relevant counterfactual for assessing harm or benefit, then genome editing will be identity affecting and the children born as a result of the procedure will neither be harmed or benefited by it.
Down-regulation of CatSper 1 and CatSper 2 genes by methamphetamine
Published in Toxin Reviews, 2022
Somaieh Mansouri, Mehdi Jalali, Mohammad Reza Nikravesh, Mohammad Soukhtanloo
Sperm mobility is one of the main factors in male fertility. First, sperm acquires the ability to move in the epididymis and then acquires fertility capacity in the female tract (Visconti and Kopf 1998). The series of changes that subsequently cause sperm to acquire fertility is called capacitation. Factors such as intracellular pH changes, Ca2+ concentration, and cAMP are essential for capacitation (Navarro et al.2008). Due to the silent transcription of the gene in the sperm, the activation of ion channels in the sperm leads to physiological changes to enable the sperm to fertilize the ovum (Lishko et al.2012). Ca2+ ion channels play an important role in capacitation and sperm motility. CatSpers (cation channel of sperm) are voltage-gated calcium channels that exist in the sperm principal piece membrane (Lishko et al.2012, Mohammadi et al.2013). Transcription of CatSper1, 3, and 4 begins in the spermatid, while CatSper2 transcription begins in the early stage of spermatogenesis (Schultz et al.2003). Studies have shown that CatSper1 and 2 play a major role in mouse sperm motility and CatSper3 and 4 in acrosome reactions (Jin et al.2005). Thus, sperm motility and acrosome reactions are Ca2+ related events.
Aluminum reproductive toxicity: a summary and interpretation of scientific reports
Published in Critical Reviews in Toxicology, 2020
The development of an oocyte begins as a primordial germ cell. Early in embryonic development these cells migrate into the future site of the ovaries, undergo meiotic cell division, and multiply, resulting in primary oocytes (primordial follicle) within the ovary. Their development is arrested until puberty, when follicle stimulating hormone (FSH) produced by the pituitary gland stimulates some to begin to mature, developing through follicle stages (primary, secondary, and if fertilized tertiary (Graafian) follicles), in the process of folliculogenesis. Most die (atresia) during these stages. During the resumption of cell division, the oocyte’s nucleus (germinal vesicle) breaks down and the first polar body (that forms concomitantly during oocyte division) is extruded. Follicle cells secrete and release estrogen that feeds back to the pituitary gland to decrease FSH release and increase luteinizing hormone (LH) release. This causes the follicle to rupture, resulting in release of the egg (ovulation), that migrates into the fallopian tubes where it can be fertilized by sperm. The ruptured follicle forms a corpus luteum, a transitory endocrine organ that secretes estrogen and progesterone. The latter feeds back to the pituitary gland to decrease LH release. The fertilized oocyte forms a mature egg cell (ovum). When the oocyte and sperm chromosomes combine, it becomes a zygote, which divides as it migrates into the uterus, creating the pregnant (gravid) state.