FetalLungExpansion

Initial lung inflation - "erectile force" by filling of the capillaries

one

experiment, Jäykkä placed un-inflated fetal lungs in a jar covered

with a

rubber membrane to simulate movement of the diaphragm. An

air-inlet tube was

connected with the trachea, and a tube for injection of

fluid inserted into the

pulmonary artery of one lung. The lung with fluid

injected into the pulmonary artery

promptly filled with air following

movement of the rubber diaphragm. When this

lung was then removed

from the jar, it was found to float in water. The other lung

did not inflate,

remained dense,

and sank in water.

Under the microscope, the alveoli of the lung injected with fluid were fully

opened,

whereas only partial opening had occurred in the other lung.

Jäykkä (1958) reported on the appearance of lungs of pre-term and full-

term

infants who died before or shortly after birth, and described two

kinds

of expansion:

(1) that characteristic of inflation by air only, and

(2)

expansion by what he termed

"erectile force." [3].

Inflation with air led to abnormal expansion in an irregular pattern with

large areas

of lung remaining uninflated while other areas appeared

overinflated. India ink

injections into the pulmonary artery revealed lack

of circulation to areas that failed

to inflate. India ink also revealed a

bypass circuit, remnant of prenatal circulation.

Infants with irregular lung

expansion of this type also frequently had hyaline

membranes and fit

descriptions in the literature of "congenital alveolar dysplasia."

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