The fetal gallbladder: morphology and morphometry by microdissection.

Abstract

Most studies of the fetal gallbladder have been performed using ultrasonography. The identification of the fetal gallbladder and the presence of gallstones have been determined this way. The purpose of this study was to investigate the morphology and morphometry of the actual fetal gallbladder by microdissection and to examine its internal features and content. Eighty-nine formalin-embalmed fetuses of CR age 35 mm to 342 mm, i.e. 10 weeks to 36 weeks gestational age (GA), were studied by hepatic evisceration. The fetal gallbladder was examined in-situ in its bed, in relation to the umbilical vein, the anterior hepatic margin and its protrusion below the inferior hepatic surface of the liver. After excision, the form, length and diameters of the gallbladder were determined and its internal surface, lumen and content also examined. The mean length of the fetal gallbladder for the gestational ages studied ranged from 2.21 mm (10 weeks GA) to 281.6 mm (32 weeks GA); the mean fundal diameter ranged from 0.4 mm (one specimen only) to 9.42.4 mm for the same period, while the infundibular width ranged from 0.41 mm (one specimen only) to 9.01.6 mm, and the antero-posterior diameter at the fundus ranged from 0.90.3 mm to 9.03.3 mm for the same period. The parameters of the gallbladder for the period examined showed a curvilinear increase in size and were consistent with the ultrasonographic studies. The distance of the fetal gallbladder from the umbilical vein was variable and, as the gallbladder lengthened, the fundus encroached the anterior hepatic margin towards 34 weeks. A descent of the gallbladder from an "intra-hepatic" position early in fetal life to a sub-hepatic position later was clearly evident. The gallbladder wall was thick in early fetal life (10-13 weeks GA) and contained crumbly debris. Bile staining occurred at 14 weeks gestational age and the mucosa took on the normal appearance with the bile having an adult colour and consistency at 20 weeks GA.