The effect of a prolonged treatment with LH/FSH-RH was studied in long-term hypophysectomized male rats bearing pituitary grafts under the kidney capsule. LH/FSH-RH was injected twice a day in 1.5% gelatin solution and control rats were injected with the vehicle alone. Two months later the animals were sacrificed. Control rats showed marked regression of spermatogenesis and only prolactin cells seemed to be active when electron microscopic observations of the pituitary grafts were made. Detectable serum FSH and LH levels were present, however, in these animals. The rats injected with LH/FSHRH showed a striking stimulation of spermatogenesis, with complete spermiogenesis in some cases. Electron microscopy of the pituitary grafts showed a predominance of prolactin cells and FSH gonadotrophs; the latter appeared to be functionally active, in contrast to the FSH cells of control grafts. The LH gonadotrophs showed variable numbers of secretory granules, but, in general, these cells were smaller than those of normal intact rats. Serum FSH was significantly higher in the LH/FSH-RH treated animals than in the controls.
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