Histomorphological Study of the Number and Location of Lymphoid Follicles in the Vermiform Appendix among Bangladeshi People of Various Ages and Genders.

Abstract

The vermiform appendix is known to play a role in immune function due to its concentration of lymphoid tissue, specifically lymphoid follicles. These lymphoid follicles do not remain confined to the mucosa but push through the muscularis mucosa and invade the submucosa. By counting the number of lymphoid follicle with their location researchers can evaluate the immune status of the Bangladeshi population across different age and sex groups. This cross-sectional descriptive study was conducted at the Department of Anatomy, Mymensingh Medical College, Mymensingh, Bangladesh and specimen were collected from autopsy laboratory of the department of Forensic Medicine of Mymensingh Medical College, Bangladesh from October 2016 to March 2017. The collected specimen was categorized into four groups: Group A (up-to 20 years), Group B (21-40 years), Group C (41-60) years and Group D (above 60 years). For this study 10 specimens from each group (total 40) were collected. Then after several tissues processing permanent histological slides were made for microscopic examination. For estimation of the number of lymphoid follicle of the vermiform appendix in the entire stained sections were examined under microscope and the number of lymphoid follicle was counted (4x objective &10x eye piece) and their number was counted and noted. From these the mean number of lymphoid follicle per age group was calculated. After counting the total number of lymphoid follicles in a histological section, the number of lymphoid follicles was located in the lamina propria and extending into submucosa were noted. Then the percentage of lymphoid follicles extending into submucosa was calculated. The mean number of lymphoid follicle was 9.40±1.07, 9.10±0.74, 5.70±1.49 and 1.80±1.03 in Group A, B, C and D respectively. It was also observed that number of lymphoid follicle gradually decreased as age advanced. The mean difference of number of lymphoid follicle between Group A&B was statistically non significant at p = or >0.05 level and differences between Group B&C, C&D, A&C, B&D, A&D were statistically highly significant at p <0.001 level. The mean number of lymphoid follicle in male was higher (9.60±1.14 in Group A, 9.14±0.90 in Group B, 5.83±1.94 in Group C, 1.83±0.98 in Group D) than that of female (9.20±1.10 in Group A, 9.00±0.00 in Group B, 5.50±0.58 in Group C, 1.75±1.26 in Group D) but mean difference between sexes in different groups was statistically non significant at p = or > 0.05 level. In the present study, the correlation between number of lymphoid follicle and age of the individual were done. It was also observed that number of lymphoid follicle gradually decreases as age advances. There is negative correlation between age and the number of lymphoid follicle and this differences was statistically highly significant where, r = - 0.934, p value was 0.001. In this study the location of lymphoid follicle in the lamina propria was 84.0%, 86.8%, 91.2% and 94.4% in Group A, B, C and D respectively and lymphoid follicles were found to extend into submucosa was 16%, 13.2%, 8.8% and 5.6% in Group A, B, C and D respectively. Here we can see that in early age percentage of extension of lymphoid follicle from lamina propria to submucosa is more than in later age. It may be due to size of lymphoid follicle. Size of lymphoid follicle was more in early ages and less in later ages. Overall, the study noted a progressive decrease in the number of lymphoid follicles as age increased.