2.What Cells Join Together to Cause Conception?

Child Studies 11 Unit 2 – Prenatal Development

Prenatal Development Introductory Questions – ANSWERS

Key Term Definition Ovum A female cell or egg needed for reproduction.

The organ in a woman’s body in which a baby develops in during Uterus pregnancy. A tube that connects the ovary to the uterus. (A woman has 2 Fallopian tube fallopian tubes).

Sperm Male cell needed for reproduction.

The process by which a sperm cell reaches the Fallopian tube, this Conception results in the beginning of a pregnancy.

Prenatal The baby’s development during a pregnancy. development The fertilized human egg. A zygote begins to develop into an Zygote embryo in the third week of pregnancy. The name for the developing baby from about the third week of Embryo pregnancy through the eighth week. The liquid that surrounds and protects the developing baby in the Amniotic fluid uterus.

The tissue that connects the developing baby to the uterus. It is rich Placenta in blood vessels that allow nutrients and oxygen to flow to the baby.

A long tube that connects the baby to the placenta and transmits Umbilical cord oxygen and nourishment from the mother’s blood to the baby. The stage of development that begins around the eighth or ninth fetus week of pregnancy and lasts until birth. (Before it becomes a fetus the fertilized egg becomes a zygote and then an embryo).

2.What cells join together to cause conception?

In order for conception to occur a sperm cell must penetrate a female egg cell in the fallopian tube.

3. What happens during the germinal stage? How long does this stage last?

The germinal stage occurs during the first two weeks of pregnancy. The Germinal stage is the first stage of prenatal development and is therefore the first stage of a baby’s development. The following occurs during the germinal stage:

 The egg becomes fertilized to form the zygote.  The zygote (while still in the fallopian tube) begins to grow through cell division. The single-celled zygote rapidly divides into two cells, then four cells, eight cells, and so on.  The zygote reaches the opening of the uterus by the fourth day of pregnancy and attaches itself to the thick lining of the uterus through a process called implantation. In this process, the zygote is covered by the uterine lining.  The zygote has grown to the size of a pin.

4. What changes might the pregnant woman feel in the germinal and embryonic stages?

 Missed menstrual period.  Breasts begin to swell.  Pressure on bladder from enlarging uterus results in the need to urinate more frequently.  Possible nausea (“morning sickness”)  Fatigue (tiredness)

5. What major changes take place in the developing baby during the embryonic stage?

The embryonic stage is the second stage of pregnancy and begins the third week of pregnancy. We refer to it as the ‘embryonic stage’ because it is what we refer to the developing baby at this point in development. The embryonic stage is typically from week 3 to week 8 of pregnancy.

The following actions take place during the embryonic stage:

Rapid Growth:  The embryo during this six-week period (week three to week eight of pregnancy) grows very rapidly.  The cells of the embryo begin to separate and develop into the major systems of the human body – heart and lungs, bones and muscles….but they do not function yet (this occurs during the rest of pregnancy)!

Development of body systems:  Approximately 27 days after conception (around 1-month/ 4 weeks) a neural tube found at the back of the developing baby has closed and becomes the brain and spinal cord. At this point the brain begins to take control of the various body systems.  By the sixth week after conception, the connections between the brain and the spine allow the first movements of the embryo.

Formation of amniotic fluid / amniotic sac:  A sac filled with fluid forms around the embryo. This is the amniotic fluid that protects the developing baby. The amniotic sac is formed from special layers of cells in the uterus and cushions the embryo from bumps or falls that the mother might have.  The embryo is approximately 1 inch long (2.5cm) and floats freely in the amniotic fluid.

Formation of the placenta and umbilical cord:  Special cells found in the uterus form the placenta and umbilical cord. The placenta is rich in blood vessels and attaches to the wall of the uterus. The umbilical cord is a tube that connects the developing baby to the placenta.  (Together these two tissues help the developing baby receive oxygen and nourishment from the mother’s blood. In addition the umbilical cord take carbon dioxide and other waste products away from the baby and to the placenta, which releases those wastes into the mother’s bloodstream). 6. What are some characteristics of a fetus at five months’ development?

At the beginning of the fifth month, the fetus is:  about 6 ½ to 7 inches (16-18cm) long and weights between 113-142 grams.  Hair, eyelashes, and eyebrows appear.  Teeth continue to develop.  Organs are maturing.  Fetus becomes more active.

7. Why do babies born at full term have a better chance for survival than babies born a few months early?

A baby born premature will not be fully developed. For example, it is only in the sixth month that the breathing movements begin, and in the ninth month the baby acquires disease-fighting antibodies from the mother blood. Also, during the last few months the fetus gains weight rapidly which helps to provide support and cushion of the organs.

8. When a mother feels lightening, what does this tell her about the fetus?

The lightening refers to the feeling the mother feels when the fetus drops into the pelvis, relieving pressure on the lungs, allowing breather to become easier.