Scientific Source #147 – Medical Textbook

“With fusion of the two pronuclei (synkaryon) fertilization is completed and marked changes occur in the organelles preparatory to the ensuing rapid cleavage division (mitotic divisions of the early zygote).” 147 147 Reid, Ryan, & Benirschke, “Principles and Management of Human Reproduction”, 1972, 176.

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Scientific Source #145 – Medical Textbook

“Reproduction depends on the union of male and female gametes (reproductive, or germ, cells) each with a half set of chromosomes, to form a new individual with a full, unique set of chromosomes.” 145 145 Human Physiology: From Cells to Systems 2nd Cd Ed,Sherwood, Kell & Ward, 2013, Nelson Education Ltd. 736.

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Scientific Source #142 – Medical Textbook

“[O]ne of two cells, male and female, whose union is necessary in sexual reproduction, to initiate the development of a new individual.” 142 142 Dorland’s Illustrated Medical Dictionary, (24th edition, 1965), 595.

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Scientific Source #140 – Medical Textbook

“[E]mbryo (em’bre-o) a new organism in the earliest stage of development; the human young from the time of fertilization of the ovum until the beginning of the third month.” ” 140 140 Encyclopedia and Dictionary of Medicine, Nursing and Allied Health (Philadelphia: WB Sanders Co., 1978) 2nd edition, 335.

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Scientific Source #139 – Medical Textbook

“[T]he beginning of the development of a new individual, is the fusion of two germ cells (gametes) of different nature; one, the spermatozoon from the male parent; the other, the ovum from the female parent. The result of this fusion is the formation of the first cell of the new individual, the zygote.” 139 139…

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Scientific Source #136 – Medical Textbook

“These pronuclei [of the sperm and oocyte] fuse with each other to produce the single, diploid 2N nucleus of the fertilized zygote. This moment of zygote formation may be taken as the beginning or zero time point of embryonic development.” 136 136 Larsen, W.J., Essentials of Human Embryology, (New York: Churchill Livingstone, 1998), 14.

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Scientific Source #134 – Medical Textbook

“The development of a human being begins with fertilization, a process by which two highly specialized cells, the spermatozoon from the male and the oocyte from the female, unite to give rise to a new organism, the zygote.” 134 134 Langman, J., Medical Embryology. 3rd edition, Baltimore: Williams and Wilkins, 1975, 3.

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Scientific Source #132 – Medical Textbook

“A zygote (a single fertilized egg cell) represents the onset of pregnancy and the genesis of new life.” 132 132 Turner, J.S. & Helms, D.B., Lifespan Development, 2nd ed., CBS College Publishing (Holt, Rhinehart, Winston), 1983, 53.

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Scientific Source #131 – Medical Textbook

“Each human begins life as a combination of two cells, a female ovum and a much smaller male sperm.” 131 131 Clark, J. ed., The Nervous System: Circuits of Communication in the Human Body, Torstar Books Inc., Toronto, 1985, 99.

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Scientific Source #130 – Medical Textbook

“The development of a new human being begins when a male’s sperm pierces the cell membrane of a female’s ovum, or egg.” 130 130 Scarr, S., Weinberg, R.A., & Levine, A., Understanding Development, Harcourt Brace Jovanovich, Inc., 1986, 86.

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