Fine structure of pituitary tumors and transplants in mice: effects on the prostate.

Abstract

AbstractTwenty‐seven primary pituitary tumors (PPT) arose in 109 mice bearing transplanted pituitary glands (TPG). Several PPT were transplanted serially into isologous hosts. Transplanted pituitary tumors (TPT) from 79 different male or female hosts were obtained between 42 and 708 days after transplantation. Histological and electron microscopic preparations of the TPG, PPT and TPT were prepared. The TPG showed much cellular necrosis and diminished secretory activity during the first month. Cellular replacement and secretory granules reappeared after revascularization of the grafts and coincident with the reappearance of somatotrophic and mammotrophic activity in the female hosts. The TPG showed no significant growth for about 1 year and about 25% of the transplants became tumorous after 400 days. EM examination of the PPT revealed heterogeneous secretory granules resembling those of the alpha and beta type in the same cell. The endoplasmic reticulum (ER) was abundant and the mitochondria were large and many were structurally abnormal. The TPT usually grew slowly but differed from tumor line to tumor line. By six months after transplantation the TPT were polynodular, with red nodules and white nodules. In both red and white tumoral nodules, the cells were PAS, reticulin, amyloid, elastin and Masson‐negative, and showed some autoradiographic activity after proline‐H3 administration. Also, the EM shows no significant difference between the nodules. Fibrils about 70 Å in diameter were in the ER, and 100–300 Å in diameter in plasma fundamentalis, and fibers larger than 300 Å in extracellular areas. The fibrillar synthesis in the TPT cells was in inverse ratio to the granular secretory activity of the cells. Sixteen of the TPT in CB 815 and 87 hybrid mice contained C‐type virus‐like particles (VP). Viral particles were noted in the periphery of the nucleus, and in the endoplasmic reticulum. Cells with the most viral particles showed the least granular secretory activity. The TPT in females were mammotrophic, and in males prostatotrophic. The prostatic epithelial cells contain cytoplasmic organelles with delicate lamellae in fingerprint, whorl, or tubular arrangement and amorphous granular aggregates. Mice with TPT for several months had enlarged prostates, some having intraluminal hyperplastic trabeculae, and cells showing less secretory activity. In mice with two lines of TPT, C‐type viral particles appeared in the prostatic cells.