Studies on Development of Respiratory Organ in Middle and Later Stages of Prenatal Life of Korean Fetus

The developmental feature of the respiratory organ including the larynx, trachea, bronchi, and lungs in middle and later stages of the fetal period has been studied by means of measuring the various diameters and weighing some of the parts of the organ. The materials used for present observation are a sum of 395 cases of the Korean fetuses including 202 cases of male and 193 cases of female aged from the 4th month to the term of the prenatal life. 1. Of the larynx antero-posterior diameter of the upper part is longer than that of the lower. The antero一 posterior diameters of the larynx are shown a reiatively rapid growth with the time until the 6 th month, are followed by a relatively slow increase thereafter, and are rapidly increased again at the 10th fetal month. 2. Of the larynx the transverse diameter of the upper part is longer than that of the lower part by the 4th month. The transverse diameters are shown a rapid increase until the 5th, are followed by a relatively slow increase with the time until the 8th, and are rapidly increased again thereafter. 3. Of the larynx the height on the anterior part is longer than that of the posterior part by the 4th month. The heights of both the anterior and posterior parts are shown a rapid increase until the 5th, are followed by slow one thereafter, and are rapidly increased again at the 10th mont