Prolactin secreting adenoma in man and the role of prolactin in spermatogenesis.

The case of a 23-year-old man with a pituitary prolactin secreting adenoma is described. With the exception of prolactin all endocrinological parameters were normal. This finding provided an ideal opportunity to assess the role of prolactin on spermatogenesis. Sperm analysis and light microscopy examination of testicular biopsy showed normal spermatogenesis. Electron microscopic studies of the testicular specimen revealed the presence of undivided spermatids, containing two or more nuclei, partially embedded in a developing common acrosome. Morphological studies demonstrated a constant "paired" situation. In most instances two sperms were contained in a single membrane; no single sperm was detected. Following treatment with 5 mg/day bromocriptine prolactin levels decreased and this peculiar abnormality disappeared. In fact, after 2 months of treatment the sperm abnormalities were markedly reduced, whereas no change was found after a period of 120 days. Since this was the only alteration found in the patient with high prolactin levels, a correlation was sought between prolactin levels and cell division. Considering the similarities between prolactin and growth hormone, it might be possible to attribute to prolactin a growth hormone role in the germinal epithelium. This action could be either direct or indirect via an intermediate growth factor.