15.A female infant is born approximately 10 weeks prematurely (at 30
weeks) and weighs 1710 g. She has respiratory distress syndrome and is
treated with endogenous surfactant. She is intubated endotracheally with
mechanical ventilation immediately after birth. Over the first 4 days after birth
the ventilator pressure and the fraction of inspired oxygen are reduced. Begin-
ning on the fifth day after birth, she has brief desaturations that become more
persistent. She needs increased ventilator and oxygen support on the seventh
day after birth. She becomes cyanotic. Further examination, echocardiogram,
and x-rays reveal left atrial enlargement, an enlarged pulmonary artery,
increased pulmonary vasculature, and a continuous machine-like murmur.
Which of the following is the most likely diagnosis?
a. Persistent foramen ovale
b. Patent ductus arteriosus
c. Ventricular septal defect
d. Pulmonary stenosis
e. Coarctation of the aorta
16.Which of the following hematopoietic tissues or organs develops from
endoderm?
a. Thymus
b. Tonsils
c. Bone marrow
d. Spleen
e. Blood islands
17.Which of the following processes places the developing heart in the
presumptive thoracic region cranial to the septum transversum?
a. Gastrulation
b. Lateral folding
c. Cranial folding
d. Neurulation
e. Fusion of the endocardial heart tubes
76 Anatomy, Histology, and Cell Biology