Both the neurenteric canal and the notochordal plate are present in the conceptus at the same time. true false
Much of the intraembryonic coelom forms within paraxial mesoderm. true false
The primitive streak first appears at the beginning of the ___ week. first second third fourth fifth
Which of the following structures is believed to be a primary organizer or inducer during organogenesis? somites notochord metanephric blastema lens placode none of the above
Cells from the primitive streak DO NOT become: endoderm intermediate mesoderm paraxial mesoderm lateral plate mesoderm amnioblasts
The primitive streak: is derived from the outer cells of the morula is formed during the second week in development persists as the cloacal membrane is the site of involution of epiblast cells to form mesoderm was done in a bathing suit, for those who remember streaking
Teratomas are: the product of teratogens malformed fetuses a type of tumor containing tissue from all germ layers derived from trophoblast none of the above
Identify the correct association: adrenal cortex - ectoderm blood vessels of the stomach - endoderm lung epithelium - mesoderm olfactory epithelium - brain liver parenchyma (functional cells) - endoderm
In the third week of human embryonic development: the amnion appears a bilaminar embryonic disc is formed the body stalk moves ventrally and joins with the yolk sac stalk to form the umbilical cord the neural plate is induced by the notochordal process and associated mesoderm the uteroplacental circulation is established
During development, the notochordal process: arises from involuting endodermal cells extends from the prochordal plate to the primitive node is involved in the induction of the primitive gut becomes the appendicular skeleton
At the caudal end of the primitive streak, ectoderm and endoderm fuse as the: notochordal canal coelom cloacal membrane neural groove notochord
The lining of the _____________ forms the lining of the embryonic gut. ectoderm hypoblast blastocyst trophoblast syncytiotrophoblast cytotrophoblast blastocoele inner cell mass notochord extraembryonic mesoderm primary yolk sac amniotic cavity intraembryonic coelom secondary yolk sac
All of the essential features of external body form are completed by the end of the ____ week. third fourth fifth sixth eighth
"Quickening" or the period when fetal movements are commonly first felt by the mother occurs: near the end of the first trimester around the middle of the second trimester at the end of the second trimester at the end of the embryonic period at the end of the fetal period
Mesoderm lateral to the notochord: is derived from hypoblast differentiates into ganglia migrates cranial to prochordal plate induces endoderm differentiation
The following organs are derived from mesoderm EXCEPT: skeletal musculature musculature of blood vessels cardiac musculature suprarenal cortex suprarenal medulla
Paraxial (somitic) mesoderm gives rise to: muscle in the stomach vertebrae muscles of mastication skeletal muscle in the trunk and extremities more than one of the above
The endodermal germ layer gives rise to the epithelium and wall of the gastrointestinal tract. true false
Somites: differentiate into myotomes which give rise
to skeletal muscle in trunk and limbs differentiate into sclerotomes which give rise to vertebrae arise from segmentation of the paraxial mesoderm differentiate into myotomes which give rise
to skeletal muscle of the limbs all of the above are correct
Following are four structures together with a germ layer. Identify the INCORRECT association: epithelium of pancreas - endoderm hair - ectoderm bone - mesoderm heart - mesoderm epithelium of lung - mesoderm
Of the following, which is derived from endoderm? muscle kidney gonads tonsils hair
Which of the following structures is NOT derived from mesenchyme? muscle fiber cartilage of the limbs white blood cell precursor epidermis blood vessel
Of the following, which is derived from endoderm? hypophysis epithelium of pharynx epithelium of anal canal enamel of the teeth muscle
During the period of development of the major organ systems, development and differentiation appear first in what region? head tail mid-embryo distal third mid-third
At the beginning of the fourth week, day 22, there are about 7-10 somites present. About how many are there at the end of the fourth week, day 28? 7-10 10-13 20-23 26-29 42-44
Almost all of the internal organs are well laid down at _________ months. 1 2 3 4 5
The space between the split layers of mesoderm is the: amniotic cavity blastocele foregut hindgut none of the above
Which of the following are NOT distinctive characteristics of the fourth week of development? neuropores somites branchial arches lower limb buds hand plates
During human embryonic development: the inner cell mass develops into the fetal portion of the placenta the yolk sac stores nutrients for the first four weeks of development the allantois stores waste products the location of cells in the morula dictates their fate
Which of the following structures does not turn under onto the ventral surface of the embryo during folding of the head? prochordal plate heart notochord pericardial cavity septum transversum
At birth, the crown-rump length of the newborn averages _______ cm. 19 28 35 44 52
The embryo is called a fetus after the: third week second month third month fourth month sixth month
Lanugo covers the body, some head hairs show, and fetal movements are felt by the mother when the fetus is about how many months old? 5 6 7 8 9
Which of the following statements about fetal age and weight shows a normal relationship? 8 weeks - 10 gm. 12 weeks - 200 gm. 20 weeks - 800 gm. 26 weeks - 1000 gm. 38 weeks - 4600 gm.
Which of the following structures is derived from paraxial mesoderm of the cervical region? enamel of the teeth smooth muscle of the gut mucous lining of the larynx sympathetic chain ganglia ureter suprarenal medulla patella skeletal muscle of the upper limb heart lining of the lungs spinal cord parenchyma of the pancreas eleventh thoracic vertebra aortic arch
Which of the following is derived from the splanchnic layer of the lateral plate mesoderm? enamel of the teeth smooth muscle of the gut mucous lining of the larynx sympathetic chain ganglia ureter suprarenal medulla patella skeletal muscle of the upper limb parietal peritoneum lining of the lungs spinal cord parenchyma of the pancreas eleventh thoracic vertebra aortic arch
Which of the following is derived from the intermediate mesoderm? enamel of the teeth smooth muscle of the gut mucous lining of the larynx sympathetic chain ganglia ureter suprarenal medulla patella skeletal muscle of the upper limb parietal peritoneum lining of the lungs spinal cord parenchyma of the pancreas eleventh thoracic vertebra aortic arch
During the fourth week in development, the growth of head, tail and lateral folds transform the flat germ disc into a tubular embryo. true false
What process converts the bilaminar disc into the trilaminar embryonic disc consisting of ectoderm, mesoderm, and endoderm? somitogenesis transformation gastrulation neurulation
What is the significance of primitive streak? It allows for the differentiation between the three layers of trilaminar disc. It allows for differentiation between caudal and cranial ends of epiblast. It specifically extends cranially and caudally to form oropharyngeal membrane and cloacal membrane. It forms the 4 limbs of the body. B and C
At end of third week, somites begin to develop along the notochord and neural tube. What do they end up forming? axial skeleton brain spinal cord sympathetic chain ganglia limbs