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Distribution of glomeruli in the renal cortex of Munich Wistar Frömter (MWF) rats
Abstract:
The glomerular distribution in the renal cortex of the Munich Wistar Frömter (MWF) rat, a substrain of the Munich Wistar rat selected for superficial glomeruli, was compared to that of a control strain (LEW/Ztm) between 10 and 150 days of age. While there were no significant differences in body growth, kidney weight, or growth of the renal cortex in these two strains, the average diameter of Bowman's capsule and of the glomerular tuft was significantly larger (about 12%) in rats of the MWF strain which were older than 60 days. In histological sections of kidneys of MWF rats in all age groups, many glomeruli in direct contact with the renal capsule were found; thus, this developmental step must have taken place before 10 days of age. The appearance of superficial glomeruli was due to a shift of glomeruli to a position just under the renal surface, the subcapsular zone or 'cortex corticis', which is normally free of glomeruli. For the rest of the renal cortex there were only slight differences in glomerular density and in total number of glomeruli per section between these two strains. These results lead us to suppose that superficial glomeruli belong to a special nephron type; thus, these glomeruli are not enveloped by parts of the proximal tubule.
Insights
The Munich Wistar Frömter (MWF) rat strain exhibits superficial glomeruli, larger in size after 60 days. These superficial glomeruli, located in the renal cortex, represent a distinct nephron type in rats.
Area of Science:
- Nephrology
- Developmental Biology
- Comparative Anatomy
Background:
- The Munich Wistar Frömter (MWF) rat is a substrain selected for superficial glomeruli.
- Understanding glomerular distribution is crucial for renal physiology research.
Purpose of the Study:
- To compare the glomerular distribution in MWF rats with a control strain (LEW/Ztm).
- To investigate the developmental origins and characteristics of superficial glomeruli in MWF rats.
Main Methods:
- Histological examination of rat kidneys across various age groups (10-150 days).
- Comparative analysis of body weight, kidney weight, renal cortex growth, and glomerular dimensions between MWF and LEW/Ztm strains.
Main Results:
- MWF rats showed no significant differences in body or kidney growth compared to controls.
- A significant increase (approx. 12%) in Bowman's capsule and glomerular tuft diameter was observed in MWF rats older than 60 days.
- Superficial glomeruli, located in the 'cortex corticis', were present in MWF rats from 10 days of age, indicating early developmental positioning.
Conclusions:
- The appearance of superficial glomeruli in MWF rats is due to their migration to the subcapsular zone before 10 days of age.
- Superficial glomeruli in MWF rats are likely a distinct nephron type, not enveloped by proximal tubules.
- This study provides insights into the unique renal anatomy and development of the MWF rat model.