Background: Urinary bladder is an organ of considerable importance in mammals, being a site where urine is collected before micturition and without undergoing any significant exchange of water or ions with surrounding. Urinary epithelium (urothelium) is unique in being non-reabsorptive and non-secretory in nature. The earlier studies on the development of urinary bladder were mainly on its gross anatomical features. Objectives: 1) To thankful to Dr. Mrs. Yelikar, Professor and Head, Department of Obstetrics and Gynecology, Aurangabad, for her support and co-operation. I am thankful to all the teachers, staff members and colleagues of department of anatomy, GMC, Aurangabad, Maharashtra for their help. Authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.note structural differentiation and maturity of muscularis externa layer which it attains at different stages of development to show the adult picture. 2) To compare and contrast differences between different age groups and with previous studies and available literature. Material and Method: 50 aborted human fetuses (29 females and 21 males) of different gestational age from 9th week onwards were collected, urinary bladder were taken out and fixed in a fixative. Blocks of tissues were made from bladder wall proper, trigone and bladder neck and processed to get sections which were stained with 1) Haematoxylin and Eosin 2) Masson__ampersandsignrsquo;s trichrome stain. Results: Beginning with 12th week, muscularis externa showed well developed circular muscle layer and a thin inner longitudinal layer in the form of thin, scattered bundles. Outer longitudinal layer appeared as discrete, nonuniform bundles of muscle fibres by 13th week. All three layers were seen well developed and thick by 16th week and found thickest by 32nd week with slight variations in their arrangement. Muscle layer thickness at bladder neck and trigone increased progressively from 18th wk onwards. Conclusion: Muscular layer in bladder wall showed all three layers progressively increased in thickness and indistinctly well developed from 16th week onwards and found thickest at 32nd week. Thus Histogenesis of urinary bladder in this instance may represent a powerful tool to delineate structure __ampersandsignndash; function relationship.