The localization and number of LH- and FSH-containing cells (LH cells and FSH cells) in the pituitary gland of prepubertal female rats aged 5, 10, 15, 20, 25 and 30 days were determined by means of immunocytochemical light microscopy of 5 μm horizontal sections. Anti-rat LHβ and anti-rat FSHβ were used in combination with the unlabelled peroxidase–antiperoxidase method.
The gonadotrophic cells were regularly distributed throughout the pars distalis but at 5 and 10 days of age fewer LH and FSH cells were found in lateral regions. The numbers of LH and FSH cells per pituitary gland increased with age. The number of LH cells per unit volume of pituitary tissue reached a maximum at 20 days; the number of FSH cells reached a maximum at 15 days and then decreased with increasing age. At all ages except 5 days more LH than FSH cells were counted per unit volume. Some cells reacting with both anti-rat LHβ and anti-rat FSHβ were detected.
Comparison of the data obtained on the dynamics of cell number with data previously obtained on pituitary gonadotrophin content suggests that at successive prepubertal ages LH and FSH cells contain increasing amounts of their respective hormones.