112 Anatomy, Histology, and Cell Biology
48.A 6 month-old boy is brought to the pediatric neurology clinic as a
referral from a pediatrician concerned about the child’s developmental
delay, ataxia, hyperventilation, and repeated episodes of vomiting. The par-
ents report one “seizure-like event.” Your examination reveals hypotonia,
some spasticity, and deafness. You note mild choreoathetosis when the boy
is attempting to move. Laboratory results show high lactate in the cere-
brospinal fluid, a muscle biopsy shows normal histology, but tests reveal a
deficiency in Cytochrome C Oxidase, complex IV. In the electron micro-
graph below, where would you expect to find that enzyme localized?
a. A
b. B
c. C
d. D
e. E
(Reproduced, with permission, from Fawcett DW:The Cell,2/e. Philadelphia:WB Saunders,
1981.)