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Fertilization was not understood in antiquity. Hippocrates believed that the embryo was the product of male semen and a female factor. Aristotle held that only male semen gave rise to an embryo, while the female only provided a place for the embryo to develop, [5] a concept he acquired from the preformationist Pythagoras.
Feet of a baby born to a mother who had taken thalidomide while pregnant. In the late 1950s and early 1960s, the use of thalidomide in 46 countries was prescribed to women who were pregnant or who subsequently became pregnant, and consequently resulted in the "biggest anthropogenic medical disaster ever," with more than 10,000 children born with a range of severe deformities, such as ...
Progesterone, secreted by the corpus luteum, inhibits the follicular growth and maintains the pregnancy. The endocrine system coincides with the menstrual cycle and goes through thirteen cycles (and thus thirteen LH spikes) during the course of normal folliculogenesis.
Pregnancy is the period of time during which the fetus develops, dividing via mitosis inside the uterus. During this time, the fetus receives all of its nutrition and oxygenated blood from the mother, filtered through the placenta , which is attached to the fetus' abdomen via an umbilical cord .
The trophoblasts secrete fluid into the blastocoel. The resulting increase in size of the blastocyst causes it to hatch through the zona pellucida, which then disintegrates. [5] This process is called zona hatching and it takes place on the sixth day of embryo development, immediately before the implantation process. The hatching of the human ...
In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth —height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed.
Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. [1] [2] Sex determination is often distinct from sex differentiation; sex determination is the designation for the development stage towards either male or female, while sex differentiation is the pathway towards the development of the phenotype.
In human fertilization, a released ovum (a haploid secondary oocyte with replicate chromosome copies) and a haploid sperm cell (male gamete) combine to form a single diploid cell called the zygote. Once the single sperm fuses with the oocyte, the latter completes the division of the second meiosis forming a haploid daughter with only 23 ...