(b) Diagram shows hatching, probably due in part to the production of a proteolytic-like enzyme by some .

The head still makes up half of your baby's body length. In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the ninth week after fertilization. Which period of prenatal development is the most critical and why? Baby's face is well-formed. Bipotential gonads, or gonads that can develop into male or female sexual organs, are connected to a central cavity called the cloaca via Mllerian ducts and Wolffian ducts. Figure 6.1 Detailed anatomy of implantation in the mammal (a) Expanded blastocyst showing the flat layer of trophectoderm cells (T) which will become part of the extraembryonic tissue and the inner cell mass (E) from which the embryo derives. It is inhibited by hypoxemia and stimulated by hyperoxemia 18. During cell . The fetal crown-rump length (CRL) is defined as the longest length of the fetus excluding the limbs and yolk sac. Hearing has developed, so the fetus can respond to sounds. By the end of week 12, the fetus measures approximately 9 cm (3.5 in) from crown to rump. 12. The cardiovascular system is fully functional. This stage occurs during the first 2 weeks of development (or the 2nd - 4th weeks of pregnancy). Every step in the gestational period is crucially orchestrated to ensure appropriate development of the embryo. Describe four methods of assessing the fetal condition during the antepartum period. The most critical period in the development of an embryo or in the growth of a particular organ is during the time of most rapid cell division. Fetal Nail Development. Poor Lifestyle Habits of Mother. Around week 11, the nail beds (the layer of cells underneath the fingernails and toenails) begin to form; then in the second trimester, tiny nails will sprout up. From 9-12 weeks, the sex organs . 11. This happens regularly and comes with actions such as swallowing, hiccupping, and yawning. Intake of fruits and vegetables or vitamin C during pregnancy was assessed by a 1-day 24-h recall method. The embryonic period is all . The third trimester can end anywhere between the 38th - 42nd week and is the 7th, 8th and 9th completed months of pregnancy. Regresses completely by 12 weeks (1st trimester) Male - forms Wolffian duct (precursor of epididymis, vas deferens and ejaculatory duct) Vestigial remnants of the . A. a pound a week throughout pregnancy. Development begins at the moment of conception, when the sperm from the father merges with the egg from the mother. By about 16 to 20 weeks: Typically, the pregnant woman can feel the fetus moving. All the major structures are already formed in the fetus but they continue to grow. The stage of development before birth is called_______________ A. Germinal period B. Prenatal stage C. Fetal period D. Embryonic period 2. By the twelfth week of fertilization the embryo moves into the final stage of development called the fetal stage. Explain the uses of amniocentesis as a diagnostic tool.

Week 12 Your little one is moving, but you won't feel it quite yet. Find step-by-step Anatomy and physiology solutions and your answer to the following textbook question: During weeks 9-12 of fetal development, _____. 10. Smoking: The best time to quit smoking is before you get pregnant, but quitting at any time during pregnancy can help your baby get a better start on life.

Describe the purpose of the nonstress test. By the eighth week of pregnancy, the embryo develops into a fetus. By the end of week 12, the fetus measures approximately 9 cm (3.5 in) from crown to rump. The first trimester is week 1 through the end of week 13 and consists of the 1st, 2nd and 3rd months. Grades 6 . Fetal Development. The .

Fetal Development Development in humans lasts about 280 days or 40 (2) weeks, from fertilization until birth. This is the same as 5 to 14 gestational weeks (weeks since the first day of your last period). As your pregnancy progresses, your baby might begin to seem more real. 4 cell stage B. This is the time when the baby grows very quickly. Take a vitamin with 400 micrograms (mcg) of folic acid every day, before and during pregnancy. The Fetal Period (Weeks 9-40) Figure 3. Two months ago, your baby was a cluster of cells.

The eyes, ears, nose, and upper lip as well as the limbs begin to develop as well. Baby responds to noise/voices in the womb. The umbilical cord is clearly visible.

Figure 23.4. There are about 40 weeks to a typical pregnancy.

Sperm go into an egg and fertilizes it. Pregnancy Week 12. An embryo weighs around 1/10th of an ounce and is roughly 1 1/2 inches long during the embryonic period and, during the fetal period, may grow to be more than 20 inches long and weigh more than 7 pounds. Your little one might just be growing into your nose or your partner's chin. Fertilization of the egg occurs in the fallopian tube, forming a zygote that divides rapidly by cleavage as it travels to the uterus. 2 cell stage B. Fertilization C. Day 21 D. Morula 2. Which period of prenatal development is the most critical and why? 9. Fingers and toes are fully developed, and fingerprints are visible. Fetal development is an amazingly complex and beautiful process. Key events of human development during the second week following fertilization or clinical gestational age GA week 4, base on last menstrual period.Week 2 is about the implantation process and blastocyst differentiation. Extra. The prenatal development of a child has three different stages: the germinal stage, the embryonic stage, and the fetal stage. These weeks are divided into three trimesters. 21.

Two months pregnant. Test your knowledge with this fetal development quiz having well-researched questions and answers. By now, the fetus has formed all of the organs and structures necessary for a baby, but those organs still need to grow and develop. An infant born six weeks prematurely has laid down only half the calcium into its bones as an infant carried to term.28 There is evidence that vitamin D plays a role in lung development, 29 and it probably plays a much larger role in fetal development in general due to vitamin D's interaction with vitamin A. The fetus's heartbeat can be detected electronically. What's happening in the baby's body: Your baby's mouth can open and close now. During the prenatal period, the development is so rapid and all takes place within 9 months. Sexual differentiation does not begin until the fetal period, during weeks 9-12. From 9-12 weeks, the sex organs begin to differentiate.

This chart shows approximate crown-rump . . This article describes the third week of embryonic development. Your baby's heart beats with a regular rhythm. The intestines rotate. D. a total of 25 to 35 lbs. The second trimester usually ends around the 26th week and consists of the 4th, 5th and 6th completed months. Weeks 13-16 are marked by sensory organ development. The 40 weeks of an average pregnancy are usually discussed in terms of three trimesters, each approximately 13 weeks. 2 to 5 lbs during the first trimester, then a pound each week until the end of pregnancy. Embryo (2 weeks through 8 weeks)attachment to uterus, heart beat begins, cell differentiation begins, recognizable body parts appear, major body systems form (organogenesis) Fetus (9 weeks to 40 weeks) body systems mature Prenatal Brain Development The neural stem cells divide and multiply, eventually producing neurons and glial cells. 18. B. Within 24 hours after fertilization, the egg that will become your baby rapidly divides into many cells. By the third month, the fetus has all its body parts including external genitalia. Fetal development From the 10 weeks of gestation (8th week of embryogenic) the developing organism is called fetus. Fertilization of the egg occurs in the fallopian tube, forming a zygote that divides rapidly by cleavage as it travels to the uterus. An egg that has been fertilized by a sperm is considered to be in the embryonic stage of development. From week 37 to 42, labor may occur List the three periods of the prenatal stage: 3. Note that all cells produced from the initial fertilization event are defined as the "conceptus" and will include cells with both embryonic and extraembryonic futures. Pregnancy Week 16 . The eyes are well-developed by this stage, but the eyelids are fused shut. Baby starts to hear sound. During that time the change from a single-celled zygote to a baby occurs. prenatal development, also called antenatal development, in humans, the process encompassing the period from the formation of an embryo, through the development of a fetus, to birth (or parturition). Questions and Answers 1. The first division after fertilization happens at what stage? At 20 weeks pregnant, your baby is the size of a sweet potato. 1 pound a week during first two trimesters, then 2 pounds per week during third. .

Weight gain accelerates. During normal prenatal development, fetal vitamin C concentrations in plasma are higher than .

Your baby's eyelids close and will not reopen until about the 28th week. At this stage, the fetus is about the size of a kidney bean and begins to take on the recognizable form of a human being as the "tail" begins to disappear. The eyelids . Since the precursors of all the major organs are created by this time, the fetal period is described both by organ and a list of changes by weeks of gestational age. (12 weeks after the first day of the last normal menstrual period) The fetus is about 2 1 / 2 -inches from head to rump and weighs about 1 / 2 ounce. Baby is more sensitive to sound. Fetal development in the first trimester occurs in stages with new organs forming about every four weeks. The first two weeks of the prenatal state is called the ____________ period A. Embryonic B. Fetal C. Germinal 4. A mere 16 days after conception, your fetus's neural plate forms (think of it as the foundation of your baby's brain and spinal cord). During the second month of the pregnancy, the spinal cord, the brain, the heart, the intestine, and the skin are formed.

Weeks 13-16 are marked by sensory organ development. a. bone marrow begins to assume erythrocyte production b. meconium begins to accumulate in the intestines c. surfactant production begins in the fetal lungs d. the spinal cord begins to be myelinated. . At about 16 weeks, the fetus is approximately 4.5 inches long.