Search results
Results from the WOW.Com Content Network
Fertilization was not understood in antiquity. Hippocrates believed that the embryo was the product of male semen and a female factor. But 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.
Chance of fertilization by menstrual cycle day relative to ovulation [15] Pregnancy rates for sexual intercourse are highest during the menstrual cycle time from some 5 days before until 1 to 2 days after ovulation. [16] For optimal pregnancy chance, there are recommendations of sexual intercourse every 1 or 2 days, [17] or every 2 or 3 days. [18]
Nine-week-old human embryo from an ectopic pregnancy. Organogenesis is the development of the organs that begins during the third to eighth week, and continues until birth. Sometimes full development, as in the lungs, continues after birth. Different organs take part in the development of the many organ systems of the body.
The placenta connects the developing fetus to the uterine wall to allow nutrient uptake, thermo-regulation, waste elimination, and gas exchange via the mother's blood supply; to fight against internal infection; and to produce hormones which support pregnancy. The placenta provides oxygen and nutrients to growing fetuses and removes waste ...
In humans, pregnancy can be defined clinically, biochemically or biologically. Clinically, pregnancy starts from first day of the mother's last period. [4] Biochemically, pregnancy starts when a woman's human chorionic gonadotropin (hCG) levels rise above 25 mIU/mL. [5] Biologically, pregnancy starts at implantation of the fertilized egg.
Prenatal development (from Latin natalis 'relating to birth') involves the development of the embryo and of the fetus during a viviparous animal's gestation.Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal development until birth.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
One ovum is released and it passes through the fallopian tube into the uterus. Hormones produced by the ovaries prepare the uterus to receive the ovum. The lining of the uterus, called the endometrium, and unfertilized ova are shed each cycle through the process of menstruation. If the ova is fertilized by sperm, it attaches to the endometrium ...