Block 1 Mini 1/2 Embr Week 2 And 3 Develop

Teratogenic insult to neural crest cells can cause DiGeorge syndrome. DiGeorge syndrome is a genetic disorder caused by a deletion of a small piece of chromosome 22. This deletion affects the development of several structures derived from neural crest cells, including the parathyroid glands, thymus, heart, and face. Neural crest cells are a group of cells that migrate during embryonic development and give rise to various tissues and structures in the body. A teratogenic insult to these cells can disrupt their normal development, leading to the characteristic features of DiGeorge syndrome.

Melanocytes are derived from neural crest cells. Neural crest cells are a group of cells that arise from the embryonic neural tube and migrate to different parts of the body, including the skin. Melanocytes are responsible for producing the pigment melanin, which gives color to the skin, hair, and eyes. Therefore, the correct answer is melanocytes of the skin.

Parafollicular cells of the thyroid gland are derived from neural crest cells. Neural crest cells are a group of cells that originate from the neural tube during embryonic development. They migrate to various parts of the body and give rise to a wide range of cell types, including parafollicular cells of the thyroid gland. These cells produce calcitonin, a hormone involved in regulating calcium levels in the body. The other options listed in the question are not derived from neural crest cells.

The medullary region of the adrenal gland is derived from the neural crest. The neural crest is a group of cells that form during embryonic development and give rise to various structures in the body, including the adrenal medulla. The adrenal medulla is responsible for producing and releasing hormones such as adrenaline and noradrenaline, which are involved in the body's response to stress. Therefore, the medullary region of the adrenal gland is derived from the neural crest.

Teratogenic insult to neural crest cells can cause DiGeorge syndrome. Neural crest cells are a group of cells that migrate during embryonic development and give rise to various structures in the body, including the parathyroid glands, thymus, heart, and craniofacial structures. If these cells are exposed to teratogens, which are substances that can disrupt normal development, it can lead to abnormalities in these structures. In the case of DiGeorge syndrome, the teratogenic insult affects the neural crest cells, resulting in parathyroid hypoplasia, thymic hypoplasia, cardiac outflow tract defects, and craniofacial abnormalities.

The gonads are derived from the intermediate mesoderm. During embryonic development, the intermediate mesoderm gives rise to the urogenital system, which includes the gonads (ovaries in females and testes in males). The gonads develop from a specific region of the intermediate mesoderm called the gonadal ridge. This region undergoes further differentiation to form the primordial germ cells, which eventually give rise to the gametes (eggs or sperm). Therefore, the correct answer is Gonads.

During the 3rd week of development, the embryonic disk is composed of two layers. The endodermal layer gives rise to the skin, while the endodermal layer migrates into the primitive streak to form the somites. However, the intermediate mesoderm is responsible for forming the kidneys and gonads. The cardiogenic area, on the other hand, is located at the base of the primitive streak.

Lateral folding is the correct answer because ectopia cordis or Pentalogy of Cantrell is a congenital malformation of the anterior body wall that occurs during the process of lateral folding in embryological development. Lateral folding is a crucial step in which the flat embryonic disc folds laterally, creating the body shape and enclosing the developing organs within the body cavity. In the case of ectopia cordis, the defect in lateral folding leads to the heart being located outside the chest.

The correct answer is that prior to closure of the neuropores, the neural tube is in open communication with the surrounding amniotic fluid. This is because during early development, the neural tube forms from the ectoderm and is initially open at both ends. The cranial neuropore closes around the 27th day of gestation, while the caudal neuropore closes around the 25th day of development. Failure of the cranial neuropore to close can result in a condition called anencephaly, which is characterized by the absence of a major portion of the brain and skull. This condition can also lead to oligohydramnios, a decrease in amniotic fluid volume.

The development of limbs is most dependent on Hox genes. Hox genes are a group of genes that play a crucial role in the development of body structures and organs in animals, including humans. They are responsible for specifying the positional identity of cells and tissues during embryonic development. In the case of limbs, Hox genes control the patterning and differentiation of cells, determining the proper formation and organization of the limbs. Without the proper expression of Hox genes, limb development can be disrupted, leading to abnormalities or absence of limbs.

Embryonic stem cells are usually prepared by dissociation of the embryoblast, which is the inner cell mass of the blastocyst. The embryoblast contains pluripotent cells that have the potential to differentiate into any cell type in the body. By dissociating the embryoblast and culturing its cells, scientists can obtain embryonic stem cells for various research and therapeutic purposes. These cells have significant potential in regenerative medicine and studying developmental processes.

The ectoderm is the germ layer that will give rise to stratified cuboidal epithelium which lines the ducts of sweat glands. The ectoderm is one of the three primary germ layers formed during embryonic development and it gives rise to various structures including the epidermis, hair, nails, and sweat glands. The stratified cuboidal epithelium is a type of epithelial tissue that consists of multiple layers of cube-shaped cells. Since sweat glands are derived from the ectoderm, the correct answer is ectoderm.

During the 3rd week of development, the endodermal layer migrates into the primitive streak to form the somites. The somites are blocks of mesoderm that give rise to various structures in the body, including the muscles and bones. The endodermal layer, on the other hand, gives rise to the simple columnar cells lining the stomach. These cells are responsible for the production of digestive enzymes and absorption of nutrients in the stomach. Therefore, the correct answer is that the endodermal layer gives rise to the simple columnar cells lining the stomach.

The aorta is the largest artery in the body and carries oxygenated blood from the heart to the rest of the body. In the case of a fetus, the most oxygenated blood flows through the aorta to supply the developing baby with the necessary oxygen and nutrients. The umbilical artery carries deoxygenated blood from the fetus to the placenta, while the pulmonary artery carries deoxygenated blood from the heart to the lungs. The femoral artery and internal carotid artery are not directly involved in supplying blood to the fetus.

During Stage 3 of labor, the placenta separates at the spongy layer of the decidua basalis. This layer is located in the uterus and is responsible for providing nutrients and support to the developing fetus. As the placenta detaches from this layer, it allows for the expulsion of the placenta from the uterus. The other options mentioned, such as the chorionic plate, the chorion and the amnion, the smooth chorion and the decidua parietalis, and the umbilical cord, are not correct as they do not accurately describe the layer from which the placenta separates during Stage 3 of labor.

The pyramids, which are formed by nerve tracts running through the caudal medulla, develop ventral to the sulcus limitans. Based on their position of embryological development, the functional association of the pyramids is motor.

The rectus capitis posterior minor is a derivative of the epaxial musculature. The epaxial musculature refers to the muscles located on the dorsal side of the body, specifically the muscles that run along the vertebral column. The rectus capitis posterior minor is a small muscle located in the posterior region of the neck, near the base of the skull. It is part of the group of muscles that help to stabilize and move the head.

The fourth ventricle is not associated with the myelencephalon and pons. The fourth ventricle is located in the hindbrain, while the myelencephalon (also known as the medulla oblongata) and pons are both part of the brainstem. Therefore, this grouping is incorrect.

Amniotic fluid does not contain nutrients and is not the main nutritional support for the fetus. The correct answer is that amniotic fluid is primarily derived from maternal blood.

Acrania is the condition characterized by the absence of the skull bones, which is a severe malformation. In the given scenario, the ultrasound scan shows a malformation, and the conditions listed are commonly associated with malformations. However, acrania is not commonly associated with the malformation shown in the scan image. Therefore, it would be unexpected to see acrania in this patient.

The correct answer is "spina bifida with meningomyleocele." Spina bifida is a congenital defect where the spinal cord does not develop properly. In this case, the newborn has a cystic mass in the lumbar region, which is consistent with a form of spina bifida called meningomyleocele. Meningomyleocele refers to a cystic sac that contains both nerve tissue (myelo) and meninges (meningo). This type of spina bifida is characterized by the protrusion of the spinal cord and meninges through a defect in the vertebral column.