Superficial nephrons in BALB/c and C57BL/6 mice facilitate in vivo multiphoton microscopy of the kidney.

Multiphoton microscopy (MPM) offers a unique approach for
addressing both the function and structure of an organ in near-real
time in the live animal. The method however is limited by the
tissue-specific penetration depth of the excitation laser. In the
kidney, structures in the range of 100 µm from the surface are
accessible for MPM. This limitation of MPM aggravates the
investigation of the function of structures located deeper in the
renal cortex, like the glomerulus and the juxtaglomerular
apparatus. In view of the relevance of gene-targeted mice for
investigating the function of these structures, we aimed to
identify a mouse strain with a high percentage of superficially
located glomeruli. The mean distance of the 30 most superficial
glomeruli from the kidney surface was determined in 10 commonly
used mouse strains. The mean depth of glomeruli was 118.4±3.4,
123.0±2.7, 133.7±3.0, 132.3±2.6, 141.0±4.0, 145.3±4.3, 148.9±4.2,
151.6±2.7, 167.7±3.9, and 207.8±3.2 µm in kidney sections from
4-week-old C3H/HeN, BALB/cAnN, SJL/J, C57BL/6N, DBA/2N, CD1 (CRI),
129S2/SvPas, CB6F1, FVB/N and NMRI (Han) mice, respectively (n = 5
animals from each strain). The mean distance from the kidney
surface of the most superficial glomeruli was significantly lower
in the strains C3H/HeN Crl, BALB/cAnN, DBA/2NCrl, and C57BL/6N when
compared to a peer group consisting of all the other strains
(p