Relative Position of Kidney in Developing Foetuses

The kidneys are developed in a craniocaudal sequence from pronephros, mesonephros and metanephros. The pronephros is rudimentary and the non-functional, second is short fuctioning and third is permanent kidney. The ascent of the kidney from the pelvic region to the abdomen is seen by the end of the 9 th week along with rotation from anterior to medial aspect. During ascent, failure to alter the position results in ectopic kidneys with or without rotational changes. So, kidneys from 20 human foetuses of different gestational age groups were studied to see the relative position of kidney. Meticulous dissection was done specifically from anterior aspect to observe the level of upper pole, hilum and lower pole of both the kidneys in relation to vertebral column and to each other, any abnormality in position during the ascent of kidney. From early gestational age to the later part, all the kidneys except two cases were found in abdominal position by the side of the vertebral column. The position varied from T10 to L5 vertebral body along with hila facing anteromedially in early gestational ages to medially in later age groups. The left cross renal ectopia with fusion of similar lower poles of both kidneys forming "L-shaped" unsymmetrical horseshoe kidney with rotational anomaly and rotational anomalies in bilateral kidneys with more rare excessive rotation of left kidney were found in two different cases. The knowledge of kidney position in different gestational age will be of immense value to the