Developing Human Clinically Embryology 9th Edition Moore Persaud - Test Bank

Moore: The Developing Human, 9th Edition Chapter 01: Gametogenesis and Fertilization Test Bank MULTIPLE CHOICE Directions: Each group of questions below consists of a numbered list of descriptive words or phrases accompanied by a diagram with certain parts indicated by letters or by a list of lettered headings. For each numbered word or phrase, select the lettered part or heading that matches it correctly and then insert the letter in the space to the right of the appropriate number. Sometimes more than one numbered word or phrase may be correctly matched to the same lettered part or heading. 1. ________ Haploid nuclei that fuse to form a zygote a. Polar body b. Capacitation c. Acrosome d. Zona pellucida e. Pronuclei ANS: E The male and female pronuclei are the haploid nuclei of the sperm and oocyte, respectively. They fuse during fertilization to form the diploid nucleus of a zygote. The nucleus occupies most of the head of the sperm, and after it enters the oocyte, it swells to form the male pronucleus. The pronuclei are about equal in size and show similar features. 2. ________ Changes occur in it that inhibit entry of sperm a. Polar body b. Capacitation c. Acrosome d. Zona pellucida e. Pronuclei ANS: D The zona pellucida undergoes changes, called the zona reaction, when a sperm contacts the cell membrane of a secondary oocyte. These changes, caused by the release of substances from the oocyte, prevent other sperms from passing through the zona pellucida and entering the oocyte. 3. ________ Contains enzymes that digest a path for the sperm a. Polar body b. Capacitation c. Acrosome d. Zona pellucida e. Pronuclei ANS: C The acrosome is a caplike structure that invests the anterior half of the head of the sperm. It contains enzymes that pass through perforations in its wall and digest a path for the sperm to follow through the zona pellucida to fertilize the oocyte. 4. ________ Polar body a. A b. B c. C d. D e. E ANS: D The first polar body forms during the first meiotic division. Note that it is inside the zona pellucida with the secondary oocyte. Although it may divide into two polar bodies, these cells degenerate. The secondary oocyte receives the same number of chromosomes as the polar body; however, it gets almost all the cytoplasm. 5. ________ Zona pellucida a. A b. B c. C d. D e. E ANS: C The zona pellucida surrounds the secondary oocyte and the polar body. This membrane is surrounded by a layer of follicular cells called the corona radiata. The zona pellucida appears homogeneous in the fresh condition, but under the electron microscope it appears granular and shows some concentric layering. 6. ________ Meiotic spindle a. A b. B c. C d. D e. E ANS: E Contact of a sperm with the cell membrane of the oocyte stimulates the secondary oocyte to complete its second meiotic division. This contact also brings about the zona reaction, preventing entry of more sperms. The sperm penetrates the cell membrane of the secondary oocyte and then passes into the cytoplasm of the oocyte, leaving its cell membrane outside the oocyte. 7. ________ Corona radiata a. A b. B c. C d. D e. E ANS: A The corona radiata consists of one or more layers of follicular cells that surround the zona pellucida, the polar body, and the secondary oocyte. The corona radiata is dispersed during fertilization by enzymes released from the acrosomes of the sperms that surround the oocyte. 8. ________ Haploid cell a. A b. B c. C d. D e. E ANS: D The polar body is the labeled haploid cell formed during the first meiotic division of the oocyte. The sperm is also a haploid cell zygote. 9. ________ Embryoblast a. A b. B c. C d. D e. E ANS: B The embryoblast (inner cell mass) is recognizable about 4 days after fertilization. It is derived from the central cells of the morula. The embryoblast gives rise to the embryo and some extraembryonic tissues. 10. ________ Gives rise to part of the placenta a. A b. B c. C d. D e. E ANS: D The trophoblast gives rise to the embryonic part of the placenta; the other part is derived from the endometrium. When the trophoblast becomes lined by extraembryonic somatic mesoderm, the combined layers are called the chorion. The trophoblast forms no part of the embryo. 11. ________ Gives rise to the hypoblast a. A b. B c. C d. D e. E ANS: B At the end of the first week, differentiation of the embryoblast gives rise to the hypoblast. It appears as a flattened layer on the ventral surface of the inner cell mass. Later, it forms the roof of the umbilical vesicle (yolk sac) and is incorporated into the embryo as the lining of the primordial gut. 12. ________ Degenerates and disappears a. A b. B c. C d. D e. E ANS: A The zona pellucida begins to degenerate about 4 days after fertilization as the blastocyst begins to expand rapidly. Implantation of the blastocyst begins on the sixth day. 13. ________ Blastocystic cavity a. A b. B c. C d. D e. E ANS: C The blastocystic cavity forms as fluid passes into the morula from the uterus and accumulates. The spaces around the central cells of the morula coalesce to form the blastocystic cavity, converting the morula into a blastocyst. The uterine fluid in the blastocystic cavity bathes the ventral surface of the embryoblast and probably supplies nutrients to the embryonic cells. 14. ________ Once filled the cavity of the ovarian follicle a. A b. B c. C d. D e. E ANS: C Follicular fluid fills the cavities of mature ovarian follicles. When the stigma of the follicle ruptures at ovulation, the oocyte is expelled with the fluid from the follicle and the ovary in a few seconds. The expulsion of the oocyte and the fluid is the result of intrafollicular pressure and, possibly, ovarian smooth muscle contraction. 15. ________ Develops under luteinizing hormone influence a. A b. B c. C d. D e. E ANS: E The corpus luteum develops under the influence of the luteinizing hormone. It produces progesterone and some estrogen. These hormones act on the endometrium, bringing about the secretory phase and preparing the endometrium for implantation of a blastocyst. If the oocyte is fertilized, the corpus luteum enlarges into a corpus luteum of pregnancy and increases its hormone production. If the ovum is not fertilized, the corpus luteum begins to degenerate about 9 days after ovulation and is called a corpus luteum of menstruation. 16. ________ Produces progesterone a. A b. B c. C d. D e. E ANS: E The corpus luteum usually produces progesterone for about 9 days. If the oocyte is fertilized, it produces progesterone until about the end of the fourth month of pregnancy. 17. ________ Expelled with the follicular fluid a. A b. B c. C d. D e. E ANS: B The secondary oocyte is expelled with follicular fluid at ovulation. Ovulation is under FSH and LH influence and occurs through the ruptured stigma. The oocyte quickly leaves the peritoneal cavity and enters the infundibulum of the uterine tube. 18. ________ Fimbriae a. A b. B c. C d. D e. E ANS: D The fimbriae of the uterine tube embrace the ovary at ovulation. The sweeping motion of the fimbriae and the motion of the cilia on their epithelial lining cells carry the oocyte into the uterine tube. 19. ________ Derived from a primary oocyte a. A b. B c. C d. D e. E ANS: B The secondary oocyte is derived from a primary oocyte after the first meiotic division. This division produces two haploid cells, the secondary oocyte and the first polar body. By the time of ovulation, the secondary oocyte has begun the second meiotic division but progresses only to the metaphase stage, where division is arrested. If the oocyte is fertilized, it completes the division, forming a mature oocyte. 20. ________ Cytotrophoblast a. A b. B c. C d. D e. E ANS: D The trophoblast of the implanting blastocyst differentiates into two layers. The internal layer is the cytotrophoblast. Rapid proliferation of cells of the cytotrophoblast give rise to the syncytiotrophoblast, a nucleated cytoplasmic mass. 21. ________ Embryoblast a. A b. B c. C d. D e. E ANS: C The embryoblast gives rise to the embryo. It arises from cells that have segregated from the morula. This occurs about 4 days after fertilization. The remaining cells of the morula become the trophoblast of the blastocyst. 22. ________ Endometrium a. A b. B c. C d. D e. E ANS: A The blastocyst attaches to the epithelium covering the compact layer of the endometrium about 6 days after fertilization. The endometrium is in the secretory phase of the uterine cycle, with abundant blood vessels and secreting glands. The endometrial cells are enlarged and filled with glycogen as well as lipids. 23. ________ Hypoblast a. A b. B c. C d. D e. E ANS: E The hypoblast appears at about 7 days after fertilization. It is a flattened layer of cells on the surface of the inner cell mass facing the blastocyst cavity. The hypoblast gives rise to the embryonic endoderm and the endoderm of the umbilical vesicle. 24. ________ Syncytiotrophoblast a. A b. B c. C d. D e. E ANS: B The syncytiotrophoblast, like the cytotrophoblast, is derived from the trophoblast. The trophoblast proliferates rapidly following implantation of the blastocyst. The syncytiotrophoblast is a multinucleated cytoplasmic mass with no discernible cell boundaries. The syncytiotrophoblast invades the uterine endometrium and facilitates implantation of the blastocyst. Moore: The Developing Human, 9th Edition Chapter 03: Formation of Germ Layers and Early Tissue and Organ Differentiation Test Bank MULTIPLE CHOICE Directions: Each group of questions below consists of a numbered list of descriptive words or phrases accompanied by a diagram with certain parts indicated by letters and a list of lettered headings. For each numbered word or phrase, select the lettered part or heading that matches it correctly and then insert the letter in the space to the right of the appropriate number. Sometimes more than one numbered word or phrase may be correctly matched to the same lettered part or heading. 1. ________ Notochordal process a. A b. B c. C d. D e. E ANS: B The notochordal process is a rod-shaped structure composed of cells derived from the primitive node of the primitive streak. It is the primordium of the notochord, a cellular structure that defines the primordial axis of the embryo. 2. ________ Site of the prechordal plate a. A b. B c. C d. D e. E ANS: A The site of the prechordal plate is indicated in the drawing by a dotted oval to indicate that it is not visible from the dorsal surface of the embryonic disc. The prechordal plate is a circular area of thickened embryonic endoderm in the cranial part of the roof of the umbilical vesicle. The prechordal plate, together with the overlying embryonic ectoderm, later constitutes the oropharyngeal membrane. 3. ________ Gives rise to most of the embryonic mesoderm a. A b. B c. C d. D e. E ANS: D The primitive streak, a linear band of epiblast, gives rise to mesoderm mainly during the third week. The mesoderm extends laterally and becomes continuous with the extraembryonic mesoderm on the amnion and umbilical vesicle. 4. ________ Primitive pit ANS: C The primitive pit is a depression in the primitive node at the cranial end of the primitive streak. It extends into the notochordal process and forms the notochordal canal. Thus, it is the entrance to the notochordal canal. The pit later forms the opening of the neurenteric canal, which temporarily connects the amniotic cavity with the umbilical vesicle. 5. ________ Aggregation of angioblasts A. Allantois B. Primitive streak C. Notochord D. Blood island E. Neural plate ANS: D Splanchnic mesenchymal cells known as angioblasts aggregate to form isolated masses called blood islands, which develop into vascular endothelium and primordial blood cells. Blood islands form first on the umbilical vesicle, chorion, allantois, and connecting stalk, but they develop in the embryo about 2 days later. 6. ________ Diverticulum of umbilical vesicle (yolk sac) A. Allantois B. Primitive streak C. Notochord D. Blood island E. Neural plate ANS: A The allantois, a diverticulum of the umbilical vesicle, is a vestigial structure that later becomes the urachus (median umbilical ligament in an adult). It serves as a reservoir for excretory products in some species, but it is nonfunctional in human embryos. However, its blood vessels become the umbilical vessels. 7. ________ Forms the basis of the axial skeleton A. Allantois B. Primitive streak C. Notochord D. Blood island E. Neural plate ANS: C The developing notochord and the adjacent paraxial mesoderm are thought to produce inductive substances that stimulate development of the neural plate from the overlying embryonic ectoderm. The notochord forms the basis of the axial skeleton. The vertebrae develop around it, and then it degenerates. In between the vertebrae, the notochord forms the primordium of the nucleus pulposus of the intervertebral disc. 8. ________ Gives rise to the brain and spinal cord A. Allantois B. Primitive streak C. Notochord D. Blood island E. Neural plate ANS: E The neural plate is a thickened area of ectoderm that overlies and extends on each side of the notochord. The neural plate invaginates to form a neural groove. In later development, the neural folds meet dorsally and fuse to form the neural tube. The cranial part of the neural tube develops into the brain, and the longer remaining part forms the spinal cord. The notochord and paraxial mesoderm produce inductive substances that stimulate or induce the overlying ectoderm to thicken and form the neural plate. 9. ________ Source of mesenchyme A. Allantois B. Primitive streak C. Notochord D. Blood island E. Neural plate ANS: B The primitive streak produces mesoderm, which develops into mesenchyme (embryonic connective tissue). Mesenchyme forms a packing tissue around developing organs and develops into connective tissues and muscles. 10. ________ Appears on extraembryonic membranes A. Allantois B. Primitive streak C. Notochord D. Blood island E. Neural plate ANS: D The blood islands first appear on the walls of the umbilical vesicle, allantois, and connecting stalk. These extraembryonic membranes are derived from the zygote, but they are not part of the embryo. Blood islands form in the embryo about 2 days after they appear on the umbilical vesicle. 11. ________ Wall of amniotic sac a. A b. B c. C d. D e. E ANS: C The amnion encloses the amniotic cavity, forming an amniotic sac. It contains fluid that bathes the embryonic disc, forming its floor. The wall of this sac consists of an inner epithelial layer of cells covered externally by extraembryonic somatic mesoderm. 12. ________ Neural groove a. A b. B c. C d. D e. E ANS: A The neural groove forms as the neural plate invaginates to form a neural fold on each side. The folds later fuse to form the neural tube, the primordium of the central nervous system (brain and spinal cord). The ectoderm lateral to the folds, surface ectoderm, gives rise to the epidermis of the skin. 13. ________ Derived from primitive streak a. A b. B c. C d. D e. E ANS: E The intraembryonic mesoderm is derived from the primitive streak. The primitive streak produces mesoderm rapidly during the third and fourth weeks. 14. ________ Embryonic ectoderm a. A b. B c. C d. D e. E ANS: B The embryonic ectoderm in the region indicated forms a neural fold. The neural folds soon fuse, converting the neural plate into the neural tube. 15. ________ Derived from paraxial mesoderm a. A b. B c. C d. D e. E ANS: C The somites are paired cubical masses derived by segmentation of the paraxial mesoderm. The first pair of somites is formed a short distance caudal to the tip of the notochord, and successive somites are progressively formed from paraxial mesoderm. Most somites appear between days 20 and 30; they give rise to the axial skeleton and its associated musculature. 16. ________ Derived from notochordal process a. A b. B c. C d. D e. E ANS: E The notochord arises by transformation of the notochordal process. The notochord is a cellular rod that defines the primordial axis of the embryo. Mesenchymal cells from the somites later surround it and give rise to the mesenchymal bodies of the vertebrae. The notochord within the developing vertebrae later degenerates. 17. ________ Gives rise to an adult body cavity a. A b. B c. C d. D e. E ANS: A The intraembryonic coelom in the area indicated becomes part of the peritoneal cavity. The coelom appears here as a space within the lateral mesoderm, splitting it into somatic and splanchnic layers. The transverse section is cut through the caudal region of the lateral extensions of the horseshoe-shaped body cavity or coelom. 18. ________ Splanchnopleure a. A b. B c. C d. D e. E ANS: D The splanchnopleure is composed of splanchnic mesoderm and endoderm and represents the future wall of the primordial gut. The endoderm gives rise to the epithelium and glands of the digestive tract, and the mesoderm gives rise to its muscular and fibrous elements. 19. ________ Fusing to form neural tube a. A b. B c. C d. D e. E ANS: B The neural folds are fusing to form the neural tube, the primordium of the brain and spinal cord. These folds form as the neural plate invaginates along its central axis to form a neural groove. 20. ________ Umbilical artery a. A b. B c. C d. D e. E ANS: B The paired umbilical arteries are branches of the dorsal aortae. They transport deoxygenated blood and waste products from the embryo to the chorionic villi of the placenta. 21. ________ Vitelline artery a. A b. B c. C d. D e. E ANS: E The vitelline arteries are branches of the dorsal aortae to the umbilical vesicle. The vitelline arteries and vitelline veins are in communication through the vascular plexus on the umbilical vesicle. 22. ________ Sinus venosus a. A b. B c. C d. D e. E ANS: A Blood enters the sinus venosus from the embryo through the cardinal veins, from the developing placenta via the umbilical vein, and from the umbilical vesicle via the vitelline veins. Blood from the sinus venosus enters the primordial heart. 23. ________ Contains umbilical vessels a. A b. B c. C d. D e. E ANS: D The umbilical cord develops from the connecting stalk. It contains the paired umbilical arteries and the umbilical vein. The umbilical cord is the vital connection between the embryo and the placenta because the umbilical vessels transport gases (e.g., oxygen), nutrients, essential substances, and waste products. 24. ________ Tertiary chorionic villus a. A b. B c. C d. D e. E ANS: C By the end of the third week, blood vessels differentiate from mesenchymal cells in the core of the secondary villi to form the tertiary chorionic villi. The blood vessels in these villi soon become connected with the primordial heart via blood vessels that differentiate in the mesenchyme of the chorion and connecting stalk. A primordial embryonic circulation is established by the end of the third week. Oxygen and nutrients in the maternal blood in the intervillous spaces diffuse through the walls of the villi and enter the embryo’s blood. Carbon dioxide and waste products diffuse from fetal blood through the walls of the villi into the maternal blood.