|Year : 2022 | Volume
| Issue : 1 | Page : 42-48
Fetal gall bladder development: A histo-morphometric study
Anamika Jaiswal1, Ankit Kaushik2, AK Singh3, DN Sinha4
1 Assistant Professor, Department of Anatomy, Soban Singh Jeena Government Institute of Medical Sciences and Research, Almora, Uttarakhand, India
2 Assistant Professor, Department of Pathology, Government Medical College, Haldwani, Uttarakhand, India
3 Professor and Head, Department of Anatomy, Government Medical College, Haldwani, Uttarakhand, India
4 Head, Department of Anatomy, Government Medical College, Haldwani, Uttarakhand, India
|Date of Submission||07-Jul-2021|
|Date of Decision||04-Aug-2021|
|Date of Acceptance||12-Dec-2021|
|Date of Web Publication||01-Feb-2022|
Department of Anatomy, Soban Singh Jeena Government Institute of Medical Sciences and Research, Almora, Uttarakhand
Source of Support: None, Conflict of Interest: None
Background: The gall bladder development in fetal life is complex and starts as early as the 4th week of gestation; the abnormal development of the gall bladder is associated with various congenital abnormalities. The objective of the present study was to study fetal gall bladder development in relation to gestational age (GA) among fetuses. Methodology: In a cross-sectional observational study of 29 fetuses, the gall bladder parameters and histological changes are evaluated at different gestational age. The fetus was categorized based on GA into three categories of <20 weeks, 21–30 weeks, and 31 weeks and above. After dissection of the abdomen, the shape and location of the gall bladder were observed. The relationship of gall bladder with liver was observed. The gall bladder length (GBL) and gall bladder width (GBW) were measured. The histogenesis of the gall bladder was observed among all fetuses and developmental changes were noted. Results: The study included 29 fetuses, 14 males and 15 females. The first, second, and third groups comprised 5, 14, and 10 fetuses. The GA ranged from 13 to 35 weeks. The mean crown-rump length (CRL) of the fetuses was 19.34 ± 6.32 cm. The mean GBL was 2.06 ± 0.83 cm and the mean GBW was 0.77 ± 0.32 cm. The GBL and GBW increased with CRL, GA, and weight. The strong positive correlation was observed between GBL, GBW with GA and CRL. On microscopy, among the first group, fetal gall bladder at 13 weeks showed solid structure with obliterated lumen and area of early canalization. The muscular layer initially was very thin and comprised only few haphazardly arranged muscle fiber in the first group, the thickness was found to be more in the second group and a well-formed adult-like muscular layer was found in the third group. The loose connective tiisue, the outer most layer was pronounced in the third group. Conclusion: The fetal gall bladder parameters show linear increase with GA and CRL. The location, size, and relation of the fundus with margin of gall bladder in fetus undergo changes with the development of the fetus. The fetal gall bladder undergoes marked histological changes during development.
Keywords: Crown rump length, fetus, gall bladder, gestational age, histology
|How to cite this article:|
Jaiswal A, Kaushik A, Singh A K, Sinha D N. Fetal gall bladder development: A histo-morphometric study. Natl J Clin Anat 2022;11:42-8
|How to cite this URL:|
Jaiswal A, Kaushik A, Singh A K, Sinha D N. Fetal gall bladder development: A histo-morphometric study. Natl J Clin Anat [serial online] 2022 [cited 2022 May 22];11:42-8. Available from: http://www.njca.info/text.asp?2022/11/1/42/337046
| Introduction|| |
The gall bladder is a blind diverticulum-like structure for the storage and release of bile into the duodenum for fat digestion. The gall bladder development in fetal life is complex and starts as early as the 4th week of gestation; the abnormal development of the gall bladder is associated with various congenital abnormalities., The development of the gall bladder is assessed by sonography for detection of abnormal growth. Although there are ultrasound-based studies describing fetal gall bladder development, the dissection-based studies are far and few.
The objectives of the study were to estimate gall bladder length (GBL) and gall bladder width (GBW) in relation to Gestational age (GA), so as to assess the relation of the above said parameters with the GA.
| Materials and Methods|| |
This cross-sectional observational study was conducted in the department of Anatomy, Government Medical College, Haldwani, Nanital, Uttarakhand, over a period of 2 years from 2018 after obtaining institutional ethical committee approval (ref- 39/IEC/01/12). The formalin-fixed fetuses from the department museum were extracted. The fetuses with any congenital malformation or deformity were excluded from the study. The crown-rump length (CRL) of the fetuses was measured. The fetuses were categorized based on GA of fetuses into three categories of 13–20 weeks, 21–30 weeks, and 31 weeks and above. Fetal dissection was performed and the abdomen was opened with a midline vertical incision, extending from xiphisternum to symphysis pubis and a horizontal incision at the level of the umbilicus. All the layers of the anterior abdominal wall were reflected in four flaps outward to expose the liver. The small intestine was removed, and the liver was lifted upward to expose the visceral surface of the liver. The shape and location of gall bladder was observed. The relationship of gall bladder with liver was observed, including gall bladder location and extension of gall bladder over inferior margin. The gall bladder was dissected out from the gall bladder fossa; the GBL from end of fundus to the beginning of cystic duct was measured. The GBW was measured between lateral margins at the widest part of the gallbladder. The descriptive statistics were applied, including mean values and standard deviation of GA, fetal weight, CRL, GBL, and GBW for all fetuses and across the three groups. The correlation coefficient of GBL and GBW concerning GA, fetal weight, and CRL was calculated and P < 0.05 was taken as significant.
The Kolmogorov - Smirnov test of normality was applied for GA, GBL, and GBW, the variables were assessed for normality and linear regression equation for GBL with GA, GBW with GA was predicted and calculated.
The histomorphological study of the gall bladder was done across all GA with emphasis on the development of gall bladder layers across three groups.
| Results|| |
The study included GBL and GBW among 29 fetuses; 14 fetuses were male and 15 fetuses were female. The first group comprised 5 fetuses; the second group comprised 14 fetuses, and the third group comprised of 10 fetuses. The GA of the smallest fetus was 13 weeks and GA of the largest fetus was 35 weeks The mean CRL of the fetuses was 19.34 ± 6.32 cm with the smallest fetus having 6.5 cm CRL and the largest having 28 cm. The mean GBL was 2.06 ± 0.83 cm with the minimum length being 1 cm and maximum length being 3 cm. The mean GBW was 0.77 ± 0.32 cm with minimum breadth being 0.3 cm and maximum breadth being 0.8 cm. The mean GBL for the male fetus was 1.99 ± 0.83 cm and the mean GBW for the female fetus was 0.69 ± 0.32 cm. The mean GBL for the female fetus was 2.13 ± 0.81 cm and the mean GBW for female fetus was 0.77 ± 0.32 cm. The mean weight of the fetuses was 1196.20 ± 0.765.11 g.
The first group comprised of 5 fetuses, 3 were males and 2 were females. The mean CRL was 9.7 ± 2.18 cm. The mean weight was 258 ± 122 g. The mean GBL in the first group was 0.82 ± 0.24 cm and mean GBW was 0.32 ± 0.12 cm, mean GBL for male fetus was 0.73 cm and mean GBW for male fetus was 0.27 cm. The mean GBL for the female fetus was 0.95 cm and the mean GBW for the female fetus was 0.4 cm. The mean GBL in the second group was 2.05 ± 0.66 cm and mean GBW was 0.84 ± 0.29 cm; the mean CRL was 18.03 ± 3.3 cm. The mean weight was 920 ± 452 g, mean GBL for male fetus was 2.08 cm, and mean GBW for male fetus was 0.78 cm. The mean GBL for the female fetus was 2.02 cm and mean GBW for female fetus was 0.87 cm.
The mean GBL in the third group was 2.7 ± 0.44 cm and mean GBW was 0.91 ± 0.22 cm. The mean CRL was 26 ± 1.58 cm. The mean weight was 2050 ± 320 g, mean GBL for male fetus was 2.64 cm, and mean GBW for male fetus was 0.84 cm. The mean GBL for female fetus was 2.76 cm and mean GBW for female fetus was 0.98 cm.
The GBL and GBW increased with CRL, GA, and weight [Graph 1], [Graph 2], [Graph 3]. The GBL and GBW increased with GA with GBL being 2.6–3.0 times more than GBW across the three groups.
In the first group, the gall bladder was rectangular, the location of the gall bladder was intrahepatic and subhepatic, and the gall bladder was not projected out of the inferior margin. In the second group, two gall bladders were rectangular and twelve were pear shaped, 14/14 gall bladder were found to be subhepatic and deeply embedded in gall bladder fossa, 4/14 gall bladder were projected out of the inferior border of liver, 10/14 gall bladders were not projected out of the inferior border of the gall bladder [Figure 1]. In the third group, one gall bladder was rectangular and 09 were of pear shaped; the location was subhepatic and embedded in gall bladder fossa in all 10 fetuses; 4 gall bladder were not projected beyond the inferior margin of the liver. In one fetus of 34 weeks GA, gall bladder was found reaching up to the inferior surface of the liver and in four fetuses gall bladder was projected out of the inferior margin of liver [Figure 2].
|Figure 1: Deeply embedded fetal gall bladder on inferior surface of liver with raised and overarching liver parenchyma on borders of gall bladder fossa (crown rump length: 16 cm)|
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|Figure 2: Bile stained fetal gall bladder on inferior surface of liver, the fundus is protruding from inferior border of liver (crown rump length: 28 cm)|
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The strong positive correlation was observed between GBL and CRL with Pearson correlation value of 0.77 and the association was significant with P < 0.00001. The GBW showed less strong positive correlation with CRL with Pearson correlation value of 0.56 and association was significant with P = 0.00147. The difference in measurement of GBL for male fetus and female fetus was not statistically significant with P = 0.336934 when P < 0.05 was taken as significant. The difference in measurement of GBB for male fetus and female fetus was not statistically significant with P = 0.101074, when P < 0.05 was taken as significant. The GA was found to have a strong positive correlation with GBL with r-value of 0.86 and P < 0.00001, when P < 0.05 was taken as significant. The GA was found to have strong positive correlation with GBB with r-value of 0.75 and P < 0.0001, when P < 0.05 was taken as significant. The weight was found to have strong positive correlation with GBL with r-value of 0.81 and P < 0.00001, when P < 0.05 was taken as significant. The weight found to have strong positive correlation with GBB with r-value of 0.69 and P = 0.000035, when P < 0.05 was taken as significant. The value of GA was found to be not differ significantly from that which is normally distributed with K-S test statistic (D) is 0.14741. The value of GBL was found to be not differ significantly from that which is normally distributed with K-S test statistic (D) is 0.16094. The value of GBB was found to be not differ significantly from that which is normally distributed with K-S test statistic (D) is 0.1443. The linear regression equation between GBL and GA was GA = 6.13376 × GBL + 14.45521. The linear regression equation between GBW and GA was GA = 13.92763 × GBW + 16.34555.
On microscopy, among the first group, fetal gall bladder at 13 weeks showed solid structure with obliterated lumen and area of early canalization was appreciated, surrounded by flat epithelial proliferation, the lamina propria, muscular layer, and outer loose connective tissue layer was not appreciated [Figure 3]. Up to the 20th week, coloumnar epithelium was appreciated, however, the muscular layer was characterized by only few haphazard bands and the outer connective tissue layer was barely visible [Figure 4] and [Table 1]. In the second group, at 23 weeks, the gall bladder up showed well-formed lumen, all the four layers of the gall bladder was appreciated with coloumnar epithelial layer, along with lamina propria, thin muscular gall bladder wall, the epithelium, and looose outer serosal layer was appreciated, however each layer showed histological changes with increase in GA. The epithelial layer was well-formed with the appearance of folds. The lamina propria was appreciated in all fetal gall bladder of the second group. The muscular layer was thin at 22 weeks of GA, followed by the appearance of wavy muscle band (M) like strand (23 weeks GA) [Figure 5] and thick, wavy bands of circular muscles at 28 weeks of GA [Table 1]. The outer loose connective tissue layer was observed. The fetal gall bladder in the third group, showed well organized high columnar epithelium, thrown in to fold (31 weeks of GA), lamina propria was identified in all fetal gall bladder of the third group, the muscular layer was found to be well formed, with muscular (M) layer extend toward subepithelial zone at some places (32 weeks of GA) [Figure 6], the external surface showed connective tissue with lymphatics (34 weeks of GA) [Table 1].
|Figure 3: Photomicrograph of gall bladder (first group) gestational age-13 weeks, shows lumen is obliterated gall bladder lumen and area of resolution (H and E, ×400)|
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|Figure 4: Photomicrograph of gall bladder (first group), gestational age-20 cm shows well-formed lumen, cuboidal epithelium, thin muscular layer (H and E, ×100)|
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|Table 1: Histological findings of fetal gall bladder at different gestational age|
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|Figure 5: Photomicrograph of gall bladder (second group), gestational age-23 weeks shows well-formed cuboidal epithelium, lamina propria and thin muscular layer (H and E, ×400)|
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|Figure 6: Photomicrograph of gall bladder (third group), gestational age-32 weeks shows well-formed cuboidal epithelium, lamina propria and thick muscular layer, outer loose connective tissue (H and E, ×400)|
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| Discussion|| |
The development of extra hepaticbiliary apparatus including gallbladder starts early at 3rd–4th weeks with liver bud formation as an outgrowth of endodermal epithelium from the distal end of the foregut. The liver bud/hepatic diverticulum cells penetrate septum transversum and form two buds called pars hepatcia and pars cystica. The pars hepatica forms liver and pars cystica develops in to gall bladder and cystic duct. At 4 weeks, the hepatic diverticulum or ductal plate develops with differentiation of cells forming hepatic trabeculae and epithelial cell proliferation. The septum transversum give rise to liver stroma. At the 5th week, hepatic architecture and vascular channel get enlarged and hematopoietic functions to appear in the fetal liver. At 5th–6th weeks, the developing liver occupied most of the abdominal cavity lying between the pericardial cavity on the top and mesonephros at the bottom. The hepatocytes cords at this stage are arranged in a fragmented manner, interrupted by the network of sinusoids. At 6th–7th weeks, the two anatomical lobes of the liver separated by an anteroposterior plane form. The portal vasculature system and hepatic venous system of the liver develop from the primitive venous system. At 7th–8th weeks, the hepatic parenchyma develops into a large rounded structure. At 8th–9th weeks, the liver is an oval-shaped structure with two symmetrical lobes and quadrate and caudate lobes can be appreciated. The hepatocytes were arranged in cord likestructure and were separated by venous sinusoids.,
The ventral outpouching on pars cystica forms the gall bladder. The vacuolization of pars cystic take place along with the expansion of the cystic duct that provided the connection to the gut. The gall bladder develops marked changes with initially a hollow tubular structure, transforming into solid structure and again recanalized at later weeks to form hollow organ. During 5th–7th week of life, the gall bladder and extrahepatic biliary apparatus become demarcated, during this period the continuity between liver cells and developing gut gets first established. At 5th–6th week, the primordial duct linking the primitive intestine and hepatic parenchyma appear. This structure is a thick-walled tube with a small lumen. The gall bladder appears as an elongated tubular, dilated, and thick wall structure with a narrow lumen. At 6th–7th week, the bile duct and common hepatic duct come in contact with the liver but without penetration into liver. The elongated, fusiform gall bladder projects by short cystic duct and joins common hepatic duct to form common bile duct. The common bile duct opens in to the second part of duodenum., The reorganization and recanalization of extrahepatic biliary apparatus starts and at the 7th week, cystic duct recanalizes but recanalization of the gallbladder occurs at later weeks. The gall bladder matures by 10–13 weeks., The fetal gallbladder grows between the 15th week to term, and its size increases linearly up to the 30th week.,
The GA in this study ranged from 13 to 35 weeks The CRL in this study ranged from 6.5 to 28 cm, with mean GBL being 2.06 ± 0.83 cm, the minimum GBL being 1 cm and the maximum GBL of 3 cm, across the groups. The largest increase in GBL was found in the third group. In a study by Hosapatna et al., the GA ranged from 12 to 36 weeks, the CRL ranged from 16.5 cm to 35.5 cm; the minimum GBL was 1.2 cm and maximum GBL was 2.9 cm with a mean length of 1.86 ± 0.44 mm. The author also found GBL to have a positive correlation with CRL and GA. In another study by Wazir and Mahajan, the range of CRL was 5.1–33.8 cm with mean GBL of 1.76 ± 0.65 cm and range was 1.11–3.35 cm. Haffajee measured GBL and GBW of 89 formalin-fixed fetuses with GA ranged from 10 weeks to 36 weeks and CRL ranging from 3.5 to 34.2 cm CRL and found linear increase in length and width up to 27.7 cm CRL and plateaus after that. However, in another study by Thounaojam et al., on 92 fetal gall bladders, the author found a sudden increase in GBL at CRL 30.0–36.2 cm and 37.8–44.0 cm with maximum variance in GBL to be present across 15.1–21.0 cm CRL and least variation was found in 8.0–15.0 cm CRL. The mean GBW was 0.74 ± 0.34 cm, with minimum breadth being 0.3 cm and maximum breadth being 0.8 cm. The GBW showed a linear increase with the increase in CRL. Haffajee also found a linear increase in GBW in the fetal period. The ratio of length and width was constant across the three groups, ranging from 2.6 to 2.75 times indicating proportionate growth of GBL and GBW across all fetuses. Haffajee also found the ratio of length to width almost constant across all weeks of development, suggesting a proportionate increase in length and width and demonstrated slender growth of gallbladder.
Chan et al. measured fetus gall bladder by ultrasound in 300 fetuses between 15 and 40 weeks of gestation and found that the GBL and anteroposterior diameter increased linearly with age up to 30 weeks of gestation and showed plateau after 30 weeks of gestation. The gallbladder is visualized in fetuses with the increase in GA and is best visualized at 24–32 weeks of gestation.
In adults, the pear-shaped gall bladder is subhepatic in position on the visceral surface of the liver and extends beyond the inferior border of the liver. In fetuses, the gall bladder is intrahepatic and is either comply. It is mbedded in the liver or covered by some liver tissue in early fetal life, but with fetal dev. Still, with the liver becomes subhepatic in position, resides in the gall bladder fossa, and gradually increases in length and reaches up to the inferior border of the liver and projects outward in the late third trimester., In the current study, the fetus was intrahepatic and was short of the inferior border of the liver in the first group. In the second group, the gall bladder was subhepatic and embedded in the gall bladder fossa. In the third group, the gall bladder of the fetus with 28 cm CRL reached up to the inferior border of the liver and four fetuses had gall bladder extended beyond the inferior border of the liver.
In the study by Thounaojam et al., the gall bladder was found to be embedded in the gall bladder fossa from 15 to 22 weeks, corresponding to 8.0–16.0 cm CRL and then becomes subhepatic in location. The author also found the gall bladder to be short of the inferior border of the liver. With the advancement in fetal life, the distance between the inferior border and gall bladder reduces. The fetal gall bladder is intrahepatic up to 17 weeks and lies in interfissural space between the liver; in later weeks, the cystic duct or fundus becomes visible but remained covered by some hepatic tissue as late as 19.4 cm CRL. The gall bladder in later weeks descends completely into the gall bladder fossa and becomes subhepatic in location.
The fundus of the gall bladder in adult life protrudes from the anterior hepatic border, but in early fetal life, the gall bladder is short of anterior margin and the distance between fundus and margin reduces with age and reaches beyond margin at nearly 29 weeks or 27.7 cm CRL. In this study also, the gall bladder fundus was also found to be reaching up to border at 28 cm CRL.
The fetal gall bladder shows marked developmental changes, extrahepatic biliary apparatus becomes demarcated as early as 5th week, initially the gall bladder and cystic duct is a solid structure while reorganization and recanalization of cystic duct start early at 6th week, the gall bladder recanalize at later weeks and matures by 10–13 weeks., In this study area of reorganization and recanalization was appreciated in the fetal gall bladder at 13 weeks. The epithelium at 13 weeks was a flattened layer, well-formed columnar epithelium was appreciated at 16 weeks and tall columnar epithelium was appreciated in second and third groups. The lamina propria was appreciated in the second and third groups. The muscular layer initially was very thin and comprised only few haphazardly arranged muscle fibers in the first group, the thickness was found to be more in second group and a well-formed adult-like muscular layer was found in this group. The loose connective tissue, outermost layers was pronounced in the third group.
The ultrasound detection of the gall bladder and its growth monitoring is important to detect or rule out any congenital abnormality associated with aberrant growth of gall bladder. In a large ultrasound-based study by Blazer et al. (2002), in nearly 1 in 875 pregnancy, gall bladder was not visualized in early pregnancy and structural abnormalities were found in nearly 41% of fetuses with nonvisualized fetuses, and the authors concluded that nonvisualization of the fetal gallbladder is associated with genetic abnormalities. The nonvisualization of fetal gall bladder on ultrasound was found to be associated with significant genetic abnormalities like trisomy 18, triploidy, cystic fibrosis, extrahepatic biliary formation like agenesis of the gall bladder, biliary atresia, complex cardiac anomaly, intrauterine growth retardation, and multisystem anomalies.
The preservation by formalin causes shrinkage of the specimen and thus anthropometric measurements of fetal gall bladder in this study could be slightly less than actual measurement and can be considered limitation of the study.
While authors of other studies believed that the nonvisualization of the gall bladder is not associated with any significant genetic abnormality in fetuses. The ultrasound can reveal an enlarged gall bladder for age in a significant number of fetuses but in most of the fetuses, an enlarged gall bladder is not associated with any significant genetic or structural abnormality of gall bladder or extrahepatic biliary apparatus.
| Conclusion|| |
The gall bladder parameters show linear increase with increase in GA and CRL. The location, size, and anatomical relation of gall bladder changes with GA. The fetal gall bladder showed marked histological changes from solid structure in early fetal life to a well-formed adult-like gall bladder in later weeks. The aberrant development can give rise to various congenital abnormalities. This dissection-based histo-morphometric study will add to existing knowledge about the development of gall bladder with regard to GA.
The authors truly thank the people who gave their bodies to science so actual investigation could be performed. Results from such investigation may possibly fabricate mankind's by and large data that can then work on open minded thought. Subsequently, these providers and their families merit our most raised appreciation.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]