Health Project By Dusan & Angus

Menstrual Cycle: Definition The menstrual cycle is the monthly cycle of changes in the ovaries and the lining of the uterus (endometrium), starting with the preparation of an egg for fertilization. When the follicle of the prepared egg in the ovary breaks, and it is released for fertilization, and then ovulation occurs. Unless pregnancy occurs, the cycle ends with the shedding of part of the endometrium, which is called menstruation.

Menstrual Cycle: How it happens Menstruation occurs when a woman bleeds through her uterus, via the vagina. It happens when the follicle of the prepared egg the ovary breaks, and it is released for fertilization, after that, ovulation occurs.

Spermatogenesis: Definition Spermatogenesis is the process of sperm producing. The entire process of spermatogenesis takes about 64 days. Sperm production begins with the beginning of puberty, usually between ages 11 to 14 in boys. It continues throughout the life of an adult male. Sperm production (spermatogenesis) is a long, but permanent, process.

Spermatogenesis: Sperm What are sperm? Sperm are the male reproductive cells. In order to produce a child, the genetic material from the sperm must combine with the genetic material from an egg, in a process called fertilization. Healthy, fully developed sperm are very small (0.05 millimetres long) and cannot be seen by the human eye. These mature sperm are special cells and they are made up of three parts: a head, neck and tail. In the head is a structure called the nucleus and it contains genetic material. The head is designed to stick to and then enter the egg. The neck provides the energy for the sperm to move. The tail moves in a pounding motion to push the sperm towards the egg.

Spermatogenesis: Sperm (continued) Where are sperm made? Sperm are made in the testes, in a number of small, tightly packed, fine tubes. The male reproductive tract is made up of the testes, a system of ducts (tubes) and other glands opening into the ducts. The testes (testis, singular) are a pair of egg- shaped glands (each 15 to 35ml in volume) that are hanging in the scrotum. The testes are needed for the normal functioning of the male reproductive system. The testes have two related but separate roles: Production of sperm. Production of the male sex hormone (testosterone). Before birth, the developing testes move down from the stomach into the scrotum. It is important for reproduction because the temperature in the scrotum is lower for 3 to 5 C than normal body

Epididymus Sperm are at different stages of their development in the testis. Within one testis, some sperm are at early stages and others are at later stages of development. It takes about 70 days to develop into the mature sperm found in semen that can fertilize an egg. When mature, sperm are released from the lining of the sperm-producing tubes and pass out of the testes into the epididymis. The Epididymis is a tube leading from each testis and it is placed at the back of the testes. The epididymis connects to the vas deferens. The epididymis is from the Greek and it means upon the twin, with twin being. While in the epididymis, sperm mature and increase mobility. The epididymis stores sperm until they are ready to be ejaculated. The smooth muscle of the epididymis helps push mature sperm.

Semen When ejaculation starts, the sperm are transported from the tail of the epididymis, through vas deferens, to the urethra in the penis. As sperm pass through the different tubes, fluid from the vesicles and prostate glands is added to the sperm. The mixture is then called semen. Semen is from the Latin and it means seed. It is estimated that during his lifetime a normal male can produce as many as 300 million sperm per day. An average, typical ejaculation contains 2 to 5 millilitres (approximately 0.5 to 1 teaspoon) of semen. There are 50 to 150 million sperm per millilitre in a typical ejaculation, or 300 to 400 million sperm in each ejaculation.

Sperm: Ejaculation At the start of ejaculation, waves of muscle contractions transport the sperm, with a small amount of fluid, from the epididymis through to the vas deferens. The mixture of fluid from the testes and other accessory glands, travels along the urethra to the tip of the penis where it is discharged (ejaculated) at the time of sexual climax (orgasm).

The Process of Fertilization: Definition Fertilization is the process by which the nucleus of a sperm (a male reproductive cell) fuses (combines) with the nucleus of an egg (a female reproductive cell; also called an ovum).

The Process of Fertilization: Where it happens The fertilization occurs in the Fallopian tubes of the female reproductive tract. It takes place within hours following sexual intercourse. Approximately 300 million sperm are entering into female's vagina during intercourse. However, only one of these sperm can actually fertilize the single female egg cell. That successful sperm cell enters the uterus and swims up the Fallopian tube where he meets the egg cell. There it passes through a zona. The zona is a thick coating that surrounds the egg.

The Process of Fertilization: How it happens The head of the sperm cell contains enzymes (certain types of chemicals) that break through the zona and make it possible for the sperm to enter into the egg. Once the head of the sperm is inside the egg, the tail of the sperm falls off. The outside of the egg, the zona, then thickens to prevent another sperm from entering. That is when the fertilization begins, when the sperm reaches the egg.

The Process of Fertilization: What happens after After fertilization in the female's Fallopian tube, the center of the sperm and egg fuse to form a new cell named the zygote. This cell contains the genetic material of the sperm (male) and the genetic material of the egg (female). As the zygote travels through Fallopian tube into the uterus, it divides, forming a group of cells. The dividing zygote gets pushed along the Fallopian tube. By approximately four days after fertilization, the zygote has about 100 cells and is called a blastocyst. When the blastocyst reaches the lining of uterus, it floats for about two days, finally being attached in the uterine wall by the sixth day after fertilization. This settling down is called implanting and implanted cells are called the embryo.

The Process of Fertilization: New life The implanted embryo continues to develop in the uterus for nine months. As the baby grows, the uterus stretches until it is about the size of a basketball. After nine months…a baby is born!

Bibliography Retrieved from the Web on March 30 th, Retrieved from the Web on March 26, Retrieved from the Web March 26, Retrieved from the Web on March 27, “Fertilization: A Sweet Love Story” Retrieved from Web on March 27, Retrieved from the Web on March 19, Content.asp?pageCode=SPERMPRODUCTION Retrieved from the Web on March 19, Retrieved from the Web on March20, 2011 Picture: Retrieved from the Web on March 29, 2011

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