STUDIES ON JAPANESE FETUSES IN UROLOGIC FIELD V FORMATION OF RENAL ARTERY IN THE FETUS

Abstract

1. Purpose of investigation
Recently, various clinical problems related to renal artery have aroused much discussion and these now constitute an important topic in urology in as much as this artery is etiologically related to renal dysfunction or to some diseases of the kidney. Accurate knowledge of renal artery is especially required for one who is engaged in renal surgery, because this artery is characterized by it's abnormal course, or so-called anomalous vessels, and it's connections.
On the other hand, since the shortcomings of pyelography can be compensated by arteriography, the state of renal artery needs to be inverstigated as a part of clinical knowledge.
The author such clinical problems as aims at the study of renal artery with reference to its development, course and anomalous vessels, as one of the series of research on the urologic organs of the fetus.
2. Methods of study
Using fresh fetal cadavers measuring more than 4 months (Those of 3 months or less are too delicate for satisfactory manipulation), an incision is made in the mid line and upper thoracic aorta is ligated at a point below the heart; air is introduced into the retroperifoneal cavity and so-called roentgenographys were made after injecting either 76% Urografin or 50% Hypaque in proper amounts. Almost clear films of the artery below the chest can be obtained in this way, which enable one to visualize the course and morphology of renal artery and it's ramifications. The materials so treated numbered 30 cadavers and a total of 60 kidneys was utilized for study. The fetuses measuring 4 months are genrally delicate but in many of these materials the course of renal artery from its origin as well as the ramifications within the renal hilus can be ascertained. Those beyond 5 months and entirely satisfactory, while in those over 8 months the terminal pertion of the artery beyond the second ramification can be visualized.
3. Results and comment.
a. Expressing the origin of renal artery in terms of the vertebral level, the majority (88.9 percent) corresponded to the position from thoracic vertebra XII lumbar I to the internal between lumbar I and II. As a rule, the right side is higher than the left by 1 intervertebral space.
b. Coursing angle of renal artery. In the adult the coursing angle of renal artery is almost that of right angle to the renal hilus, but in the fetus it forms an oblique angle since the kidney is in its ascending course. This angle, in most cases, lies between 50° and 75°.
c. Length of renal artery. Admitting the natural difference in the length of renal artery according to the number of gestation months, the length varies from 8 to 15mm in fetuses of 8-10 months the discrepancy between the right and the left being 1-3mm.
d. Ramification types of renal artery. Abnormal ramifications are found rather frequenty (23. 2 percent) in renal artery, the locations most commonly involved being in the middle portion, rarely near the hilus. Special attention must be paid to those which take abnormal courses.
e. Number of ramification and state of distribution of renal artery. Renal artery usually ramifies into 2-5 branches in the hilus. The upper, middle and lower branches or several branches radiate from the hilus as if coursing widely throughout the kidney parenchyma. These branches continue to ramify still further and become distributed gradually into deep (peripheral) parts. It is uncommon to encounter crossing or entangled branches of these branches. In arteriography here employed, it is impossible to trace the branches beyond the first ramification in fetuses of low gestation age, but in many instances the second ramification and even one beyond this can be visualized. The peripheral portion assumes the shape of divided rootlets or dendritic, many terminating as needles.
f. So-called anomalous vessel. Anomalous vessel is the one having their origin from an abnormal portion of the abdominal aorta and