Background: The metanephric glomeruli develop from the metanephric blastema and ureteric bud. The nephron anlage undergoes multiple differentiation stages, fusion and invagination that lead to the formation of nephron. Objectives: To describe the morphological changes and transformations that lead to formation of metanephric permanent glomerulus during peri-natal period. Method: The study was performed on albino rat as a model for mammalian embryonic development. Embryos of 20-22 days of gestation and neonatal litters were investigated for renal development. The specimens were double fixed, plastic embedded and semi-thin sections stained with methylene blue were examined. Results: It was shown that glomerular development continues during late pre-natal days and first week post-natally. Maturity was attended by the end of the 7th post-natal day. The developing glomerulus passes through the stages describes as vesicle, comma, S-shaped, double comma, elongation and ovale stage to become finally mature. Conclusion: The metanephric glomerulus passes through sequential, multi-stage, pleomorphic development during peri-natal period. These features should be considered during evaluation of kidney during this period.
Background: The functional and morphological development of the glomerlus is an essential part of nephrogenesis that takes place during Intra uterine life and early post-natal days. Objectives: To study the morphometric parameters of the maturation of the glomerular filtration slit of the kidney during neonatal period and its implication on the function of the kidney. Method: Rat litters are used as a mammalian model of the development during the first 8 days of post -natal life. Image analysis using Bell software system was used for morphmetric measurement of filtration silt as examined by electron microscope. Results: The width of the filtration slit of new born kidney was 11.24±1.6 nm which increased by increment to be 14.83±1.6 nm on 4th.post- natal day. Eventually reached 25.34±4.3 nm on day 8 post natally. Conclusions: In New Born litters, the glomerular filtration slit is narrower than that of mature kidney. Glomerular development continues to take place during first post natal week to reach the adult mature parameters at the end of neonatal period. This explains the low GFR found in new born mammals.