Chronology Of Nephrogenic Events In Staged Aborted Human Embryos And Fetuses

ABSTRACT

Introduction: The description given in various textbooks and literature on development of nephrons in humankidney doesn’t include details of chronology of nephrogenic events at various fetal ages. Though several studieswere reported the knowledge on development of kidney especially on the nephrogenesis are limited. The studiesemphasize the relationship between prenatal development of kidney and adult onset of renal diseases. Hence, anattempt was made in this study to obtain information by observing the serial sections of kidney of embryos andfoetuses of different gestational ages for better understanding of nephrogenic events.Material and methods: Thirty-five aborted embryos and dead fetuses of 5 weeks gestational age to full term wereutilized for this study. The specimens were subjected to routine tissue processing and haematoxylin and eosin(H&E) staining. 5 embryos of less than 8 weeks gestational age were processed as a whole and were seriallysectioned. The histological sections of 5 microns thickness were observed for the time of appearance of variousnephrogenic components and photographed.Results: Differentiating pronephric, mesonephric and metanephric components in different weeks i.e. 05 – 12, 13– 24, 25-36 were studied. In 06 – 12 weeks group a delay in the appearance of Pro and mesonephric, Meso andmetanephric ducts were observed that appeared during the 6th week. Differentiation of other components havenot completed by 6th week when compared with literature. In 13 – 24 weeks also there is delay in corticomedullary differentiation that was observed at 16 wks. at which time the morphologically recognizable Nephronswere also observed. Major part of development occurred between 16-28 weeks instead of 16-24weeks as statedin the literature. Ampulla division continued beyond 24 weeks. Increased number of mature nephrons wereobserved between 24-28 weeks instead of 16-20 wks., nephron arcades were observed during 24-28 weeksinstead of 14-22weeks.Conclusion: Detailed findings of this study could aid the embryologists, neonatologists and nephrologists tounderstand the chronology of nephrogenic events and related consequences of developmental abnormalities.