stages of prenatal development ......pptx

Stages of prenatal development

1. presentation title: stages of prenatal development Class: B, 2 nd year medical school. School of medicine & Surgery

2. Prepared by 1.Ali Hussein ali 2. Haboon Hassan adnan 3.imran abdi ali 4. Nimco abdilaahi suldaan 5. Nimco Derie Hirsi 6. Safa faarah mohomud 7.suhayb ahmed faarah

3. Overview Prenatal development is a foundational aspect of developmental psychology, encompassing the process by which a human embryo and fetus develop during pregnancy, from conception to birth. This period is divided into three primary stages: germinal stage embryonic stage fetal stage

4. Germinal stage The germinal stag e is a critical period in prenatal development, characterized by rapid cell division, formation of the blastocyst, and implantation in the uterine wall. Also known as Zygote stage. occurs first two weeks after conception. Fertilization and Formation of the Zygote Fertilization: Occurs when a sperm cell from the male merges with an ovum (egg) from the female, forming a zygote. This usually happens in the fallopian tube. It contains a complete set of 46 chromosomes (23 from each parent) and represents a single cell that will undergo rapid cell division After fertilization occurs, the zygote remains in the fallopian tube for about 72 hours.

5. Cleavage Cleavage: The process of rapid mitotic divisions that the zygote undergoes, resulting in an increase in the number of cells without an increase in overall size. This process starts about 24- 30 hours after fertilization. Blastomeres: The cells produced during cleavage are called blastomeres. These cells continue to divide and form a solid ball of cells known as the morula.

6. Blastulation Process: Transformation of the morula into a blastocyst. Tming: Occurs from roughly day 5 to day 7 after fertilization. Morula changes from a solid ball of undifferentiated cells into a fluid- filled ball of differentiated cells. Major Parts of the Fully Formed Blastocyst: Embryoblast (Inner Cell Mass): Mass of cells inside the blastocyst and Will develop into the embryo. Trophoblast: is Outer cell layer of the blastocyst Will implant in the uterus. Develops into the placenta and other embryonic tissues. Blastocoele : Cavity formed by the migration of embryoblast cells to one pole of the blastocyst. Fills with fluid secreted by trophoblast cells.

7. Formation of the Placenta: Trophoblast cells differentiate into structures that will form the chorion and eventually the placenta, providing nutrients and oxygen to the developing embryo. Human Chorionic Gonadotropin (hCG): The trophoblast cells produce hCG, a hormone that maintains the corpus luteum and thus progesterone production, which is essential for maintaining the uterine lining and pregnancy.

8. implantation Travel to the Uterus: The blastocyst travels down the fallopian tube towards the uterus. This journey takes about 5-7 days after fertilization. Implantation in the Uterine Wall: The blastocyst attaches to the endometrium, the lining of the uterus. The trophoblast cells begin to invade the endometrium to secure the blastocyst in place and start forming the placenta. Implantation marks the end of the germinal stage and the beginning of the embryonic stage.

9. Potential Issues: Risks During the Germinal Stage Ectopic Pregnancy This occurs when the blastocyst implants outside the uterus, commonly in the fallopian tube. Consequences: An ectopic pregnancy cannot proceed normally and poses a serious health risk to the mother, often requiring medical intervention. Causes: Potential causes include damage to the fallopian tubes, hormonal imbalances, or infections. Failure to Implant: Description: The blastocyst fails to properly attach to the uterine wall. Consequences: This results in the loss of the blastocyst and often manifests as an early miscarriage, sometimes before the mother realizes she is pregnant. Causes: Factors such as chromosomal abnormalities, insufficient uterine lining, or hormonal issues can prevent successful implantation. Chromosomal Abnormalities: Causes: These errors can occur randomly but are more common with advanced maternal age or certain genetic conditions.

10. The Embryonic Stage: A Period of Rapid Growth Germinal Stage : The first two weeks after conception are characterized by rapid cell division, implantation, and the formation of the blastocyst. Embryonic Stage : This crucial stage, spanning weeks 3 through 8, witnesses the development of major organs and body systems. Fetal Stage : Beginning from week 9, the fetus continues to grow and mature, developing a distinct human form.

11. Embryonic Development: A Symphony of Organ Formation Neural Tube The neural tube develops into the brain and spinal cord, laying the foundation for the nervous system. Heart The heart begins to beat and pump blood, signifying the start of circulatory function. Limbs Tiny buds appear, which will later develop into arms and legs, marking the beginning of limb formation.

12. Psychological Influences: Shaping the Developing Mind 1. Maternal Stress High levels of maternal stress can have a negative impact on the developing fetus, affecting cognitive and emotional development. 3. Environmental Toxins Exposure to environmental toxins, such as lead and mercury, can pose significant risks to the developing fetus, leading to various health issues. 4. Maternal Mental Health Maternal mental health conditions, such as depression and anxiety, can impact the developing fetus, influencing their emotional and social development. 2. Maternal Nutrition A healthy diet rich in essential nutrients is crucial for optimal fetal growth and development, including brain development.

13. Potential Psychological Conditions Linked to the Embryonic Period Autism Spectrum Disorder Disruptions in the early development of the nervous system may contribute to the onset of autism spectrum disorder, characterized by challenges in social interaction and communication. Attention Deficit Hyperactivity Disorder (ADHD) Alterations in the formation and connectivity of the brain's neural networks during the embryonic stage can increase the risk of ADHD, a condition marked by inattention, hyperactivity, and impulsivity.

14. The Embryonic Period: Key Processes and Developments An In- depth Look from Weeks 2 to 8

15. Cell Differentiation

16. Development of the Placenta and Amniotic Sac Placenta: Site of nutrient and waste exchange. Amnion: Protective fluid- filled sac around the embryo.

17. Organogenesis Major organ and structure formation. Neural Tube Formation: Develops into the brain and spinal cord. Heart Development: Begins beating around the third or fourth week. Limb Buds: Early development of arms and legs. Eyes and Ears: Initial formation.

18. Pharyngeal Arches: Development of face, neck, and related structures. Somites: Formation of vertebrae, ribs, and skeletal muscles. Essential Structures and Features

19. Vulnerability to Teratogens Definition of teratogens and their impact. Examples: Drugs, alcohol, infections, environmental toxins. Consequences: Structural anomalies and developmental disorders.

20. Important Milestones by Week Weeks 2- 3: Germ layer differentiation. Weeks 3-4: Neural tube and heart formation. Weeks 4- 5: Limb buds, eyes, and ears formation. Weeks 5- 6: Brain, heart chambers, facial structures development. Weeks 6- 8: Growth of organs and limbs with fingers and toes.

21. Why prenatal development is important? Prenatal development is important because the more we know about the process of a growing baby, the more we can do to ensure the baby and mother are healthy throughout gestation. It is also important so new moms can watch what they consume and do to minimize chances of harming the baby. •

22. Fetal stage From the ninth week until birth, the organism is referred to as a fetus. During this stage, the major structures are continuing to develop. By the 12th week, the fetus has all its body parts including external genitalia. From 9–12 weeks, the sex organs begin to differentiate. At about 16 weeks, the fetus is approximately 4.5 inches long. Fingers and toes are fully developed, and fingerprints are visible.

23. Cont. By the time the fetus reaches the sixth month of development (24 weeks), it weighs up to 1.4 pounds. Hearing has developed, so the fetus can respond to sounds. The internal organs, such as the lungs, heart, stomach, and intestines, have formed enough that a fetus born prematurely at this point has a chance to survive outside of the mother’s womb.

24. Throughout the fetal stage the brain continues to grow and develop, nearly doubling in size from weeks 16 to 28. Around 36 weeks, the fetus is almost ready for birth. At nine weeks, the embryo's ballooning brain allows it to bend its body, hiccup, and react to loud sounds.

25. At week ten, it moves its arms, "breathes" amniotic fluid in and out, opens its jaw, and stretches. Before the first trimester is over, it yawns, sucks, and swallows as well as feels and smells. By the end of the second trimester, it can hear; toward the end of pregnancy, it can see.

26. FETAL ALERTNESS Scientists who follow the fetus's daily life find that it spends most of its time not exercising these new abilities but sleeping. At 32 weeks, it drowses 90 to 95% of the day. Some of these hours are spent in deep sleep, some in REM sleep, and some in an indeterminate state, a product of the fetus's immature brain that is different from sleep in a baby, child, or adult. During REM sleep, the fetus's eyes move back and forth just as an adult's eyes do, and many researchers believe that it is dreaming.

27. DiPietro speculates that fetuses dream about what they know- - the sensations they feel in the womb. Closer to birth, the fetus sleeps 85 or 90% of the time the same as a newborn

28. Fetal movement • Awake or asleep, the human fetus moves 50 times or more each hour, flexing and extending its body, moving its head, face, and limbs and exploring its warm wet compartment by touch. Heidelise Als , a developmental psychologist at Harvard Medical School, is fascinated by the amount of tactile stimulation a fetus gives itself. "It touches a hand to the face, one hand to the other hand, clasps its feet, touches its foot to its leg, its hand to its umbilical cord," she reports.

29. Cont. Als believes there is a mismatch between the environment given to preemies in hospitals and the environment they would have had in the womb. She has been working for years to change the care given to preemies so that they can curl up, bring their knees together, and touch things with their hands as they would have for weeks in the womb.

30. Cont. DiPietro has also noted some odder fetal activities, including "licking the uterine wall and literally walking around the womb by pushing off with its feet." Laterborns may have more room in the womb for such maneuvers than first babies. After the initial pregnancy, a woman's uterus is bigger and the umbilical cord longer, allowing more freedom of movement. "Second and subsequent children may develop more motor experience in utero and so may become more active infants.

31. FETAL TASTE By 13 to 15 weeks a fetus' taste buds already look like a mature adult's, and doctors know that the amniotic fluid that surrounds it can smell strongly of curry, cumin, garlic, onion and other essences from a mother's diet. Whether fetuses can taste these flavors isn't yet known, but scientists have found that a 33-week- old preemie will suck harder on a sweetened nipple than on a plain rubber one.

32. Cont. During the last trimester, the fetus is swallowing up to a liter a day of amniotic fluid, notes Julie Mennella, a biopsychologist at the Monell Chemical Senses Center in Philadelphia . She thinks the fluid may act as a "flavor bridge" to breast milk, which also carries food flavors from the mother's diet.

33. FETAL HEARING A very premature baby entering the world at 24 or 25 weeks responds to the sounds around it, observes Als, so its auditory apparatus must already have been functioning in the womb. Many pregnant women report a fetal jerk or sudden kick just after a door slams or a car backfires.

34. Cont.. According to DiPietro . Sounds include the whooshing of blood in the mother's vessels, the gurglaing and rumbling of her stomach and intestines, as well as the tones of her voice filtered through tissues, bones, and fluid, and the voices of other people coming through the amniotic wall. Fifer has found that fetal heart rate slows when the mother is speaking, suggesting that the fetus not only hears and recognizes the sound, but is calmed by it.

35. Fital vision • Vision is the last sense to develop. A very premature infant can see light and shape; researchers presume that a fetus has the same ability. Just as the womb isn't completely quiet, it isn't utterly dark, either. Says Filer: "There may be just enough visual stimulation filtered through the mother's tissues that a fetus can respond when the mother is in bright light," such as when she is sunbathing.

36. • A six-month fetus , born about 14 weeks too early, has a brain that is neither prepared for nor expecting signals from the eyes to be transmitted into the brain's visual cortex, and from there into the executive- braanch frontal lobes, where information is integrated. When the fetus is forced to see too much too soon, says Als , the accelerated stimulation may lead to aberrations of brain development.

37. Fetal learning • Fetal learning refers to the process by which a fetus can acquire information and form memories while still in the womb. Research has shown that fetuses can respond to sensory stimuli and exhibit basic forms of learning. • These activities can be rudimentary, automatic, even biochemical. For example, a fetus , after an initial reaction of alarm, eventually stops responding to a repeated loud noise. The fetus displays the same kind of primitive learning, known as habituation, in response to its mother's voice, Fifer has found.

38. DeCasper discovered that within hours of birth, a baby already prefers its mother's voice to a stranger's, suggesting it must have learned and remembered the voice, albeit not necessarily consciously, from its last months in the womb. the fetus can listen, learn, and remember at some level, and, as with most babies and children, it likes the comfort and reassurance of the familiar.

39. Fetal personality • In the first formal study of fetal temperament in 1996, DiPietro and her colleagues recorded the heart rate and movements of 31 fetuses six times before birth and compared them to readings taken twice after birth. (They've since extended their study to include 100 more fetuses .) Their findings: fetuses that are very active in the womb tend to be more irritable infants. Those with irregular sleep/wake patterns in the womb sleep more poorly as young infants. And fetuses with high heart rates become unpredictable, inactive babies.

40. Cont.. • Behavior doesn't begin at birth," declares DiPietro . "It begins before and develops in predictable ways." One of the most important influences on development is the fetal environment. As Harvard's Als observes, "The fetus gets an enormous amount of 'hormonal bathing' through the mother, so its chronobiological rhythms are influenced by the mother's sleep/wake cycles, her eating patterns, her movements."

41. • The hormones a mother puts out in response to stress also appear critical. DiPietro finds that highly pressured mothers-to-be tend to have more active fetuses --and more irritable infants. • DiPietro's studies show that the fetuses of poor women are distinct neurobehaviorally -less active, with a less variable heart rate--from the fetuses of middle-class women. Yet "poor women rate themselves as less stressed than do working middle-class women," she notes. DiPietro suspects that inadequate nutrition and exposure to pollutants may significantly affect the fetuses of poor women.

42. Stress, diet, and toxins may combine to have a harmful effect on intelligence A recent study by biostatistician Bernie Devlin, of the University of Pittsburgh, suggests that genes may have less impact on IQ than previously thought and that the environment of the womb may account for much more. "Our old notion of nature influencing the fetus before birth and nurture after birth needs an update," DiPietro insists. "There is an antenatal environment, too, that is provided by the mother."

43. • Parents-to-be who want to further their unborn child's mental development should start by assuring that the antenatal environment is wellnourished , low-stress, drug-free. Various authors and "experts" also have suggested poking the fetus at regular intervals, speaking to it through a paper tube or " pregaphone ," piping in classical music, even flashing lights at the mother's abdomen. • Does such stimulation work? More importantly: Is it safe? Some who use these methods swear their children are smarter, more verbally and musically inclined, more physically coordinated and socially adept than average. Scientists, however, are skeptical .

44. conclusion In summary, the stages of prenatal development—germinal, embryonic, and fetal—are crucial periods in human growth that lay the foundation for later health and development. The germinal stage involves fertilization and implantation, the embryonic stage is characterized by the formation of major organs, and the fetal stage involves growth and maturation. Understanding these stages helps in recognizing the importance of early development and the potential impacts of various environmental factors on long-term outcomes.