Embryology quiz

WIKIQUIZ

Questions reviewed by:

Mr David Kilroy MVB CVMA MRCVS David Bainbridge VetMB MA PhD MRCVS

1

In the embryo, what structure does the falciform ligament contain? The mesonephric duct The common bile duct The umbilical vein The ductus venosus The yolk sac Please select an option Incorrect. The mesonephric duct drains the embryological form of the kidney, the mesonephros. In the male it develops into the Wolffian duct which develops into the epididymis, vas deferens and seminal vesicles. In females the mesonephric duct regresses. The falciform ligament in the adult, which carries the round ligament of the liver in its free border, is the remnant of ventral mesogastrium that conveyed the umbilical vein from the umbilicus to the liver in the foetus. WikiVet Article: Falciform ligament Incorrect. The common bile duct enters the duodenum at the major duodenal papillae (with the pancreatic duct) on the dorsal surface of the duodenum. The falciform ligament in the adult, which carries the round ligament of the liver in its free border, is the remnant of ventral mesogastrium that conveyed the umbilical vein from the umbilicus to the liver in the foetus. WikiVet Article: Falciform ligament Correct!. The falciform ligament in the adult, which carries the round ligament of the liver in its free border, is the remnant of ventral mesogastrium that conveyed the umbilical vein from the umbilicus to the liver in the foetus. WikiVet Article: Falciform ligament Incorrect. The ductus venosus links the umbilical vein to the caudal vena cava. The falciform ligament in the adult, which carries the round ligament of the liver in its free border, is the remnant of ventral mesogastrium that conveyed the umbilical vein from the umbilicus to the liver in the foetus. WikiVet Article: Falciform ligament Incorrect. The yolk sac is an extraembryonic membrane which outpockets from the foetal midgut. It acts as a primitive placenta and allows the development of the vitelline circulation within the embryo. The falciform ligament in the adult, which carries the round ligament of the liver in its free border, is the remnant of ventral mesogastrium that conveyed the umbilical vein from the umbilicus to the liver in the foetus. WikiVet Article: Falciform ligament

2

During development, the intestines rotate around the cranial mesenteric artery. Through how many degrees do they rotate in the dog? 270 degrees 90 degrees 45 degrees 360 degrees 180 degrees Please select an option Correct! The early gut is a straight tube but later rotates through 270 degrees so that the adult configuration is attained. WikiVet Article: small intestine development. Incorrect. The early gut is a straight tube but later rotates through 270 degrees so that the adult configuration is attained. WikiVet Article: small intestine development. Incorrect. The early gut is a straight tube but later rotates through 270 degrees so that the adult configuration is attained. WikiVet Article: small intestine development. Incorrect. The early gut is a straight tube but later rotates through 270 degrees so that the adult configuration is attained. WikiVet Article: small intestine development. Incorrect. The early gut is a straight tube but later rotates through 270 degrees so that the adult configuration is attained. WikiVet Article: small intestine development.

3

In the adult, what structure does the septum transversum form? The greater omentum The parietal peritoneum The lesser omentum The ventral portion of the diaphragm The mediastinum Please select an option Incorrect. The septum transversum, or caudal wall of the pericardial cavity, is formed of unsplit mesoderm. This structure, which is conspicuous in early embryos, extends from the ventral body wall and is the beginning of the diaphragm; however, it gives rise only to its ventral portion. There are also muscular contributions to the diaphragm from other sources. WikiVet Article: liver. Incorrect. The septum transversum, or caudal wall of the pericardial cavity, is formed of unsplit mesoderm. This structure, which is conspicuous in early embryos, extends from the ventral body wall and is the beginning of the diaphragm; however, it gives rise only to its ventral portion. There are also muscular contributions to the diaphragm from other sources. WikiVet Article: liver. Incorrect. The septum transversum, or caudal wall of the pericardial cavity, is formed of unsplit mesoderm. This structure, which is conspicuous in early embryos, extends from the ventral body wall and is the beginning of the diaphragm; however, it gives rise only to its ventral portion. There are also muscular contributions to the diaphragm from other sources. WikiVet Article: liver. Correct! The septum transversum, or caudal wall of the pericardial cavity, is formed of unsplit mesoderm. This structure, which is conspicuous in early embryos, extends from the ventral body wall and is the beginning of the diaphragm; however, it gives rise only to its ventral portion. There are also muscular contributions to the diaphragm from other sources. WikiVet Article: liver. Incorrect. The septum transversum, or caudal wall of the pericardial cavity, is formed of unsplit mesoderm. This structure, which is conspicuous in early embryos, extends from the ventral body wall and is the beginning of the diaphragm; however, it gives rise only to its ventral portion. There are also muscular contributions to the diaphragm from other sources. WikiVet Article: liver.

4

What is the temporal sequence of events in the formation of a mature mammalian kidney? Mesonephros, metanephros Pronephros, metanephros Pronephros, mesonephros, metanephros. Pronephros, metanephros, mesonephros Pronephros, mesonephros. Please select an option Incorrect. Before mesonephros there is pronephros. WikiVet Article: kidney development. Incorrect. Between pronephros and metanephros is mesonephros. WikiVet Article: kidney development. Correct! The kidney develops in the order of pronephros, mesonephros and then metanephros. WikiVet Article: kidney development. Incorrect. The correct order is pronephros, mesonephros and metanephros. WikiVet Article: kidney development. Incorrect. After mesonephros there is metanephros. WikiVet Article: kidney development.

5

What determines gonadal differentiation in to a male? Presence of Mullerian ducts Presence of mullerian inhibitory substance (MIS) Absence of SRY gene Presence of SRY gene Presence of mesonephric ducts Please select an option Incorrect. Presence of Mullerian ducts does not influence gonadal differentiation, they are primative structures present in the early embryo which will develop further or regress later in development. The correct answer is gonadal differentiation is determined by the presence of the SRY gene of the Y chromosome (sex determining region of the Y chromosome) which encodes “testicular determining factor” protein (TDF). Lack of SRY gene (i.e. XX females) leads to ovarian differentiation. WikiVet Article: genital development Incorrect. Mullerian inhibitory substance is produced by the testes and induces development of the mesonephric (Wolffian) duct system in to epididymis and vas deferens and causes regression of paramesonephric (Mullerian) duct. The correct answer is gonadal differentiation is determined by the presence of the SRY gene of the Y chromosome (sex determining region of the Y chromosome) which encodes “testicular determining factor” protein (TDF). Lack of SRY gene (i.e. XX females) leads to ovarian differentiation. WikiVet Article: genital development Incorrect. Lack of the SRY gene (i.e. in XX females) leads to ovarian differentiation. The correct answer is gonadal differentiation is determined by the presence of the SRY gene of the Y chromosome (sex determining region of the Y chromosome) which encodes “testicular determining factor” protein (TDF). WikiVet Article: genital development Correct! Gonadal differentiation is determined by the presence of the SRY gene of the Y chromosome (sex determining region of the Y chromosome) which encodes “testicular determining factor” protein (TDF). Lack of SRY gene (i.e. XX females) leads to ovarian differentiation. WikiVet Article: genital development Incorrect. Presence of mesonephric ducts does not influence gonadal differentiation, they are primative structures present in the early embryo which will develop further or regress later in development. The correct answer is gonadal differentiation is determined by the presence of the SRY gene of the Y chromosome (sex determining region of the Y chromosome) which encodes “testicular determining factor” protein (TDF). Lack of SRY gene (i.e. XX females) leads to ovarian differentiation. WikiVet Article: genital development

6

From which germ layer is the heart derived? Paraxial mesoderm Non neural ectoderm Splanchnic mesoderm Endoderm Intermediate mesoderm Please select an option Incorrect. The axial skeleton and dermal muscle of the body are derived from paraxial mesoderm. The heart and tissue around the gut are derived from splanchnic mesoderm. WikiVet Article: gastrulation. Incorrect. The epidermis of the skin is derived from non neural ectoderm. The heart and tissue around the gut are derived from splanchnic mesoderm. WikiVet Article: gastrulation. Correct! The heart and tissue around the gut are derived from splanchnic mesoderm. WikiVet Article: gastrulation. Incorect. The pharynx, lungs, liver and lining of the gut are derived from endoderm. The heart and tissue around the gut are derived from splanchnic mesoderm. WikiVet Article: gastrulation. Incorrect. Parts of the reproductive system and the kidneys are derived from intermediate mesoderm. The heart and tissue around the gut are derived from splanchnic mesoderm. WikiVet Article: gastrulation.

7

Which pair of aortic arches form the internal carotid arteries? Fourth arches Second arches Sixth arches Third arches First arches Please select an option Incorrect. The left fourth aortic arch contributes to the arch of the aorta. The right fourth aortic arch forms the proximal segment of the right subclavian artery. The third arches form the internal carotid arteries. WikiVet Article: aortic arches. Incorrect. The second arches degenerate completely. The third arches form the internal carotid arteries. WikiVet Article: aortic arches. Incorrect. The proximal segment of the right sixth aortic arch forms part of the right pulmonary artery while the distal segment atrophies. The proximal segment of the left sixth arch forms part of the pulmonary artery while the distal segment forms the ductus arteriosus. The third arches form the internal carotid arteries. WikiVet Article: aortic arches. Correct! The third aortic arches form the internal carotid arteries. WikiVet Article: aortic arches. Incorrect. The first arches degenerate completely. The third arches form the internal carotid arteries. WikiVet Article: aortic arches.

8

In the foetus, the ductus venosus shunts blood between which two structures? Umbilical vein and caudal vena cava Pulmonary artery and aorta Right ventricle and left ventricle Right atrium and left atrium Umbilical vein and portal vein Please select an option Correct! The ductus venosus bypasses the liver by linking the umbilical vein to the caudal vena cava. The flow of blood is controlled by a sphincter, enabling the proportion travelling to the heart via the liver to be altered. WikiVet Article: foetal circulation. Incorrect. The ductus arteriosus connects the pulmonary artery to the aorta and allows equivalent ventricular function in the foetus. The ductus venosus bypasses the liver by linking the umbilical vein to the caudal vena cava. The flow of blood is controlled by a sphincter, enabling the proportion travelling to the heart via the liver to be altered. WikiVet Article: foetal circulation. Incorrect. There is no physiological shunt between the right and left ventricle in the foetus. The ductus venosus bypasses the liver by linking the umbilical vein to the caudal vena cava. The flow of blood is controlled by a sphincter, enabling the proportion travelling to the heart via the liver to be altered. WikiVet Article: foetal circulation. Incorrect. The foramen ovale is an opening between the two atria enabling blood to be channelled from the right to left atrium thereby bypassing the lungs. The ductus venosus bypasses the liver by linking the umbilical vein to the caudal vena cava. The flow of blood is controlled by a sphincter, enabling the proportion travelling to the heart via the liver to be altered.WikiVet Article: foetal circulation. Incorrect. There is no physiological shunt between the umbilical vein and the portal vein in the foetus. The ductus venosus bypasses the liver by linking the umbilical vein to the caudal vena cava. The flow of blood is controlled by a sphincter, enabling the proportion travelling to the heart via the liver to be altered. WikiVet Article: foetal circulation.