1.Facts of Life: This report on the "Y" chromosome reveals more than just its link to maleness. It illustrates the role of the "Y" in determining that only men are prone to certain diseases, and why it is only a small number of "Y" genes that seem to be responsible for a lot of "male" behavior. 2.Attack on the Clones: Human culture has been evolving for millennia, but at some point, genetic engineering could alter the species itself. This report studies...

A mother explains that after her membranes ruptured and her water broke, she began to experience the first phase of labor, or early labor. For her this first phase took about six hours, but the average time is variable, lasting from two to six hours. Rarely it can last up to 24 hours. During early labor, the pressure of repeated regular contractions causes the cervix, which is closed when labor begins, to open up to a diameter of 1.2 inches (3 centimeters)...

A 21st-century remake of Miracle of Life, one of the most popular NOVA episodes of all time, this program uses high-tech methods to tell the inside-the-womb story of human life, from conception to birth. As in the original film, the program features the extraordinary work of Swedish photographer Lennart Nilsson-who improves on his earlier vision with sophisticated microscopy and high-tech medical imaging to reveal every hidden milestone in a baby's...

Although children 7 to 12 still need their physical safety and health protected, they also require strong role models, boundaries, and positive feedback to develop fully. This video will take the viewer through two stages: (1) middle childhood, when children build on what they learned in early childhood, and (2) early adolescence, when children begin to undergo the changes associated with puberty. During these years, children typically pull away from...

From the earliest stages, a growing embryo requires nutrition, oxygen, and a disposal system for metabolic wastes and a way to prevent some harmful substances from getting into its blood stream. These requirements are met by the placenta and its blood barrier. Around day 8 of development the blastocyst, a hollow ball of cells, moves into the uterus. The blastocyst's outer layer begins to extend and it implants in the uterine lining, seeking uterine...

A vasectomy is a procedure to cause permanent sterility in a man by preventing the transport of sperm out of the testes. A small incision is made in the scrotum and each vas deferens is tied off and cut apart to prevent sperm from being released within the ejaculate. The small skin incision is stitched closed and the surgery does not affect a man's sexual function.

The placenta, which was the baby's lifeline over the nine months of the pregnancy, is pushed out of the uterus. The pushing is done by contractions, with some help from the doctor, who works the placenta free of the uterus by gently pressing on the mother's abdomen. This painless process takes about 15 minutes. Once the placenta is delivered, the doctor examines it to see whether it is healthy and in one piece. Sometimes the placenta can break off...

During intercourse, sperm are released into the vagina near the cervix, swim through the uterus, and travel up the fallopian tubes. Sperm are composed of three parts: a head, a middle section, and a tail. The tail propels the sperm, which is powered by energy cells stored in the middle section. The head of the sperm contains the man's genetic material and an enzyme-filled cap needed to help the sperm penetrate through the outer membrane of the egg....

Key male reproductive organs include the testes, urethra, vas deferens, prostate gland, seminal vesicles, and penis. The testes contain coiled structures called seminiferous tubules, which are the sites of sperm production. A woman's ovaries usually produce only one egg per month, while a man's seminiferous tubules produce more than 12 billion sperm per month. On top of the seminiferous tubules is the epididymis. The immature sperm migrate there to...

Emily's mother explains that when the egg and sperm meet in the mother's fallopian tube, instructions for building a baby are contributed by the sperm. If the sperm is carrying an X, the baby will be a girl, and if it is carrying a Y, the baby will be a boy.