To evaluate proliferation of steroidogenic luteal cells, paraffin-embedded
tissues were stained for 3@-hydroxysteroid dehydrogenase
(3/3HSD) and BrdU using a streptavidin-biotin/streptavidin-alkaline
phosphatase double staining system (Histostain-DS, Zymed, San Francisco,
CA). Briefly, rehydrated sections were treated with 2 N HCl for 30
min and then rinsed in tap water, followed by two changes of PBS
containing 0.3% Triton X-100. Endogenous peroxidase activity was
quenched by incubating the sections in 3% hydrogen peroxide in absolute
methanol for 10 min. The sections were treated with the first
blocking buffer [Zymed; 10% (vol/vol) normal goat serum in PBS] for
10 min. Tissue sections were incubated for 90 min at 22 C with rabbit
anti-J@HSD polyclonal antibody [Oxygene, Dallas, TX; 1:lOO dilution in
PBS and Triton X-100 with l-2% (vol/vol) goat serum]. Control sections
were incubated with normal rabbit serum (Vector) in place of the primary
antibody. Sections were rinsed twice in PBS and incubated with biotinylated
secondary antibody (Zymed; goat antirabbit IgG) for 10 min.
After rinsing twice in PBS, sections were incubated with streptavidinperoxidase
conjugate (Zymed) for 10 min, then rinsed twice in PBS. The
color reaction was developed by incubating sections for 15 min in a
chromogen-substrate mixture for peroxidase (Zymed; hydrogen peroxidase/amino-ethyl
carbozole), which produces a reddish brown deposit.
Sections were washed twice in distilled water and incubated in double
staining enhancer (Zymed) for 30 min. During the second round of
staining, the same tissue sections were rinsed with distilled water and
incubated with the second blocking buffer [Zymed; 10% (vol/vol) normal