Multiple endobronchial metastases from carcinoma of prostate

Endobronchial metastases have been described for many types of extrathoracic malignancies. Metastases of this type from carcinoma of the prostate are rare. A case is presented of a patient whose chief complaint was hemoptysis and who had multiple endobronchial metastases from prostatic adenocarcinoma.     

Intracellular pathways of endocytosed tracers in Leydig cells of the rat

The endocytic activity of Leydig cells was examined by electron microscopy following the injection, into the interstitial space, of tracers used to examine fluid-phase endocytosis, ie, native ferritin and horseradish peroxidase-colloidal gold (horseradish peroxidase-gold), and adsorptive endocytosis, ie, cationic ferritin. At 5 minutes after injection, native ferritin or horseradish peroxidase-gold was present in the interstitial space and free in the lumen of large endocytic vesicles forming at the cell surface. At 15 minutes, these tracers appeared in the matrix of pale multivesicular bodies, while at 30 minutes and 1 hour, the matrix of dense multivesicular bodies became labeled. Beginning at 1 hour, dense membrane-delimited bodies identified cytochemically as lysosomes were labeled. In the case of cationic ferritin, two distinct pathways were taken. In one pathway, cationic ferritin was observed 5 minutes after injection bound to the plasma membrane of Leydig cells and to the membrane of small and large endocytic vesicles. At subsequent time intervals, cationic ferritin appeared consecutively in pale, dense multivesicular bodies and lysosomes. In a second pathway, cationic ferritin was observed at 5, 15, and 30 minutes bound to the membrane of vesicles of intermediate size seen near the cell surface. At 1, 1 1/2 and 2 hours, cationic ferritin-containing intermediate vesicles appeared in increasing number in the Golgi region. However, cationic ferritin was never observed in the Golgi saccules themselves. At later time intervals (3-6 hours), intermediate vesicles labeled with cationic ferritin progressively disappeared from the Golgi region and the cell. Thus in Leydig cells, while fluid-phase tracers reached lysosomes exclusively, cationic ferritin, a tracer of adsorptive endocytosis, not only reached the lysosomes, but was also carried by the intermediate vesicles to the Golgi region of the cell.     

Structural changes of the head components of the rat spermatid during late spermiogenesis

The transformation of the nucleus, acrosomic system, and perinuclear theca (perforatorium and post-acrosomal dense lamina) was analyzed during the maturation phase, i.e., steps 14 to 19 of spermiogenesis. Following partial condensation of chromatin from steps 11–14, the nucleus continues to condense during the following steps until the end of spermiogenesis. The redundant nuclear envelope which forms along the apical and ventral aspects of the nucleus and around the implantation fossa regresses during steps 17–19. The acrosomic system splits into two portions early in step 15 to give rise to: (a) the main portion with its crest-like acrosome running along the dorsal aspect of the nucleus and head cap extending over the lateral surfaces of the nucleus; and (b) a smaller head-cap segment which is seen in steps 15 and 16 along one side of the nucleus at its apical extremity. This separated head-cap segment reaches the apical-ventral aspect of the head during step 17 and condenses in synchrony with the rest of the acrosomic system in step 19 of spermiogensis. The large crescentic acrosome, which in step 15 forms a large fin at the caudal extremity of the acrosomic apparatus, moves anteriorly during steps 16 and 17, while the whole acrosomic system extends farther apically beyond the tip of the nucleus. The perforatorium and post-acrosomal dense lamina form a rigid capsule (perinuclear theca) that covers tightly the sickle-shaped nucleus and binds the inner acrosomal membrane and the post-acrosomal membranes. The post-acrosomal dense lamina, which includes the ventral spur, appears early in step 15 as a dense cytoplasmic layer applied to the nucler envelope at the caudal extremity of the nucleus except over the perifossal zone. The perforatorium forms during step 19 of spermiogenesis as a result of the condensation of a wispy cytoplasmic material which has accumulated in the subacrosomal space during steps 14–18. Thus the spermatid's head is deeply modified during the maturation phase and takes its definitive shape only at the last step of spermiogenesis.     

Binding and internalization in vivo of [125I]hCG in Leydig cells of the rat

The present study was performed to demonstrate the binding, mode of uptake, pathway and fate of iodinated human chorionic gonadotropin ([125I]hCG) by Leydig cells in vivo using electron microscope radioautography. Following a single injection of [125I]hCG into the interstitial space of the testis, the animals were fixed by perfusion with glutaraldehyde at 20 minutes, 1, 3, 6 and 24 hours. The electron microscope radioautographs demonstrated a prominent and qualitatively similar binding of the labeled hCG on the microvillar processes of the Leydig cells at 20 minutes, 1, 3, and 6 hours. The specificity of the [125I]hCG binding was determined by injecting a 100-fold excess of unlabeled hormone concurrently with the labeled hormone. Under these conditions, the surface, including the microvillar processes of Leydig cells, was virtually unlabeled, indicating that the binding was specific and receptor-mediated. In animals injected with labeled hCG and sacrificed 20 minutes later, silver grains were also seen overlying the limiting membrane of large, uncoated surface invaginations and large subsurface vacuoles with an electron-lucent content referred to as endosomes. A radioautographic reaction was also seen within multivesicular bodies with a pale stained matrix. At 1 hour, silver grains appeared over dense multivesicular bodies and occasionally over secondary lysosomes, in addition to the structures mentioned above, while at 3 and 6 hours, an increasing number of secondary lysosomes became labeled. At 24 hours, binding of [125I]hCG to the microvillar processes of Leydig cells persisted but was diminished, although a few endosomes, multivesicular bodies and secondary lysosomes still showed a radioautographic reaction. No membranous tubules that were seen in close proximity to, or in continuity with, endosomes and multivesicular bodies were observed to be labeled at any time interval. Likewise, an attempt to correlate silver grains with small coated or uncoated pits, the stacks of saccules of the Golgi apparatus and other Golgi-related elements including GERL, proved unsuccessful, since these structures were mostly unlabeled. These in vivo experiments thus demonstrate the specific binding of [125I]hCG to the plasma membrane of Leydig cells predominantly on their microvillar processes, and the subsequent internalization of the labeled hCG to secondary lysosomes. In addition, binding and internalization of hCG persisted for long periods of time.