Prenatal Development Stages PDF

Development Learners and Various Stages Why are pregnant mothers advised not to smoke, not to drink alcoholic drinks, not to take any medication without doctor’s advice? Ms. Christmas PRE-NATAL PERIOD PRENATAL PERIOD PRENATAL  (Latin...

Development Learners and Various Stages Why are pregnant mothers advised not to smoke, not to drink alcoholic drinks, not to take any medication without doctor’s advice? Ms. Christmas PRE-NATAL PERIOD PRENATAL PERIOD PRENATAL  (Latin) “pre-” before + “(g)natus,” birth = before birth.  Development between conception and birth PRENATAL PERIOD THREE STAGES germinal stage embryonic stage fetal stage  PRENATAL Cleavage is the first stage of GERMINAL PERIOD development in a human embryo, and it involves a series of mitotic STAGE Cleavage cell divisions that occur after fertilization  PRENATAL PERIOD EMBRYONIC STAGE  PRENATAL PERIOD FETAL STAGE STAGES OF PRE-NATAL DEVELOPMENT GERMINAL PERIOD  The two-week period after conception  This includes the creation of zygote, continued cell division and the attachment of the zygote to the uterine wall.  After fertilization, the male (sperm) and female a. 24 to 30 hours (egg) chromosome unite The fertilization ovum, zygote, divides into two b. 36 hours (2); 2 cells c. 48 hours (2 days) 2 cells become 4 cells 4 cells become a small compact ball of d. 72 hours (3 days) 16-32 cells e. 96 hours (4 Hollow ball of 64 -128 cells Days) Inner cell mass (blastocyst) still free in the uterus f. 4-5 days Blastocyst attaches to the wall of g. 6-7 days uterus h. 11-15 days Blastocyst invades into uterine wall and becomes implanted in it (implantation) Blastocyst – the inner layer of cells that develops during the germinal period, develops later into the embryo. Trophoblast - the outer layer of cells that develops also during the germinal period, later provides nutrition and support for the embryo. EMBRYONIC PERIOD Two weeks after conception. In this stage, the name of the mass cells, zygote, become embryo. Cell differentiation intensifies a Life-support systems for the embryo develop b c Organs appear As the zygote gets attached to the wall of the uterus, layers of cells are formed….  EMBRYO’S ENDODERM  inner layer of cells that develops into the digestive and respiratory systems.  OUTER LAYER OF CELLS  ECTODERM- is the outermost layer which becomes the nervous system, sensory receptors (eyes, ears, nose) and skin parts (nails, hair).  MESODERM – is the middle layer which becomes the circulatory, skeletal, muscular, excretory and reproductive systems. Organogenesis - the process of organ formation during the first two months of pre-natal development. As 3 layers of the embryo form, the support systems for the embryo develop rapidly…  PLACENTA – is a life-support system that consists of a disk-shaped group of tissues in which small blood vessels from the mother and the offspring intertwine but do not join  UMBILICAL CORD - contains two arteries and one vein that connects the baby to the placenta  AMNION – is a bag or an envelope that contains a clear fluid in which the developing embryo floats All these embryo life-support systems develop from the fertilized egg and not from the mother’s body. FETAL PERIOD  2 months to 7 months after conception  Growth and development continue dramatically during this period. Developmental process ( Santrock, 2002) 3 months Fetus is about 3 inches long and weighs after about 1 ounce concepti on Fetus has become active, moves its arms and legs, open and closes it mouth and moves its head; the face, forehead, eyelids, nose, chin can now be distinguished. The genitals can now be identified as male or female 4 months Fetus is about 6 inches long and after weighs 4 to 7 ounces concepti on Growth spurt occurs in the body’s lower parts Pre-natal reflexes are stronger, mother feels arm and leg movements for the 1st time 5 Fetus is about 12 inches long and months weighs close to a pound after concepti on Structures of the skin (fingernails, toenails) have formed Fetus is more active 6 Fetus is about 14 inches long and months weighs one and half pound after concepti on Eyes and Eyelids are completely formed; fine layer of head covers the head Grasping reflex is present and irregular movements occur. 7 months Fetus is about 16 inches after long and weighs 3 pounds concepti on 8 and 9 Fetus grows longer and gains months substantial weight, about 4 after pounds. concepti FACTORS AFFECTING PRENATAL PERIOD TERATOLOGY AND HAZARDS TO PRENATAL DEVELOPMENT TERATOLOGY Is the field that investigates the causes of congenital (birth) defects. A teratogen is that which causes birth defects. It comes from the Greek word “tera” which means “monster”. A. CLUSTERS OF HAZARDS TO PRE-NATAL DEVELOPMENT (Factors Affecting Pregnancy) 1.PRESCRIPTION AND NONPRESCRIPTION DRUGS -Antibiotic is an example of a prescription drug that can be harmful. Examples of harmful non- prescription drugs are diet pills, aspirin, and coffee.  2. PSYCHOACTIVE DRUGS -These include nicotine, caffeine and illegal drugs such as marijuana, cocaine and heroin. -Heavy drinking by pregnant women results to the so-called fetal alcohol syndrome (FAS) which is a cluster of abnormal ties that appear in the children of mothers who drink alcohol heavily during pregnancy.  3. ENVIRONMENTAL HAZARDS -These include radiation in jobsites and X-rays, environmental pollutants, toxic wastes, and prolonged exposure to heat in saunas and bath tubs.  4. OTHER MATERNAL FACTORS -Rubella (German measles) -Syphilis- damages organs after they have formed. Mother can infect her child in 3 ways 1. during gestation across the placenta, 2. during delivery through contact with maternal blood or fluids, and 3. postpartum (after birth) through breast feeding.  FOLIC ACID It is necessary for pregnant mothers. Can reduce the risk of having a baby with a serious birth defect of the brain and spinal cord, called the ‘neutral tube’ 5. PATERNAL FACTORS - Fathers exposure to lead, radiation, certain pesticides and petrochemicals may cause abnormalities in sperm that lead to miscarriage or disease such as childhood cancer. B. THREATS TO PRENATAL  1. MISCARRIAGE - When the baby is lost before the 20th week of gestation - Beyond this, it is already considered as stillbirth. - Chromosomal abnormalities is the most common reason  2. ECTOPIC PREGNANCY - When the zygote is implanted along fallopian tube or elsewhere outside the uterus  3. COMPLICATION ASSOCIATED TO PREGNANCY - When gestation, hormonal and biological changes are expected rapidly that can cause loss of pregnancy Ms. Christmas H. Gabia LEARNING TASK  Pretend you are “Junior”, 4 months old in the womb. Your mother is concentrating on doing abortion. Write her a letter convincing her that you are a human being developing contrary to what she and other pro-abortionists are thinking. Describe to her the development that has already taken place in 4 months. Reflect what you learned on pre-natal development. Ms. Christmas