The Growth of the Gastro-Intestinal Tract of the Human Fetus.

Abstract

A quantitative study has been made of the lineal growth of the gastro-intestinal tract in human fetuses, ranging from 2.35 to 37.5 cm. in total or crown-heel length. One hundred and three preserved specimens were available for this study.

When the lengths of the stomach as a whole, of the pylorus, of the duodenum and of the appendix are plotted against the total body-length, the values follow the course of a straight line and may be expressed by the general formula:

where “D” is the length of the segment of the digestive tract in question, “L” is the total body-length and “a” and “b” are empirically determined constants. The graphs of these relationships are shown in the following figure. The empirical formulae for these dimensions were determined from the 5 cm. interval averages of crown-heel length by the method of means, weighting by the square root of the number of cases.

The growth in length of the entire stomach, with respect to total body-length, may be represented by the empirical formula:

The mean weighted absolute deviation of the calculated values from the observed means is 0.049 cm., which is about one-fifteenth of the average interquartile mcasure of variability of the observed means used in this study.∗ The corresponding relative deviation is 4.17 per cent.

The growth in length of the pylorus may be represented by the empirical formula:

The computed means by this formula show an average weighted departure of 0.015 cm. from the observed 5 cm. range averages. The mean weighted relative deviation is 4.0 per cent. The mean weighted deviation is approximately one-tenth of the average of the interquartile measures of variability of the observed means.