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Fig. 8.4
Localization of A
undiff
in a three-dimensional reconstruction. Computationally reconsti-
tuted three-dimensional image of the seminiferous tubules based on 280 serial sections. A
undiff
(
green
) show biased localization to the blood vessel network (
red
) and the area adjacent to the inter-
stitium (
yellow
). (
a
,
c
) and (
b
,
d
), without or with blood vessels, respectively.
Roman numerals
indicate the stage of the seminiferous epithelium. Reprinted with permission from Yoshida et al.
(
2007b
)
showed a further preference to the branching point of these vessels. The live imaging
clearly revealed that, upon differentiation, the spermatogonia migrate out of these
specified areas and spread to all over the basal compartment (Fig.
8.5
) (Yoshida
et al.
2007b
).
Based on these observations, we concluded that the area of the basal compart-
ment that faces the surrounding vasculature serves as the niche for A
undiff
(Fig.
8.6a
)
(Yoshida et al.
2007b
; Yoshida
2008b
). Moreover, because the actual stem cells
consist a part of A
undiff
, these sites might also act as a niche for the stem cells.
However, we could not deny the possibility that actual stem cells are localized
independently of the vasculature, and that the A
undiff
spermatogonia that are destined
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