Removal of basement membrane in the involuting breast

Morphologic and immunohistochemical studies by light and electron microscopy indicated that basement membrane was removed during the process of involution of the murine breast. Removal of the basement membrane started 2 days postweaning, was maximal at 4 days, and correlated with degeneration of epithelial cells. There was no evidence of phagocytosis of basement membrane, so the removal of this antigen was attributed to enzymatic hydrolysis. To determine the activity of breast homogenate on the specific basement membrane antigen, insoluble basement membrane embedded in agarose gels was incubated with breast liver and kidney homogenates. When basement membrane antigen was demonstrated by the specific antibody, it was found that breast homogenate solubilized basement membrane but liver and kidney failed to solubilize basement membrane. To quantify the reaction and determine some of the characteristics of the responsible enzyme(s), insoluble basement membrane was labeled with 125I and the release of radioactivity into the supernatant following incubation with extracts of involuting breast indicated hydrolysis of basement membrane. Extracts of breast homogenate extensively hydrolyzed labeled basement membrane if naturally occurring inhibitors were removed by previous washing, whereas liver or kidney extracts prepared in a similar manner were devoid of activity. The hydrolysis of basement membrane was time and concentration dependent and had a pH optimum. The reaction was blocked by prior heating of the extract at 100 degrees C. for 30 minutes, removal of divalent cations, and presence of diisopropylfluorophosphate (a specific serine esterase inhibitor); prolonged dialysis failed to remove the hydrolytic activity. It is concluded that an enzyme system present in the involuting breast is capable of basement membrane hydrolysis

Cystosarcoma phyllodes with liposarcomatous stroma

A case of cystosarcoma phyllodes with liposarcomatous stroma is presented. Electron-microscopic study revealed lipid-containing tumor cells admixed with other mesenchymal cells devoid of fat, correlating well with the light-microscopic findings. The literature is briefly reviewed.

Existence of receptors bound to endogenous estradiol in breast cancers of premenopausal and postmenopausal women

The amounts of free and occupied estrogen receptors were determined in cytosols and cellular (cytoplasmic + nuclear) extracts of 23 human breast cancers. In vivo undersaturation of the receptors was observed in all tumors. A positive correlation was found between the degree of saturation and the concentration of circulating estrogens in premenopausal women. The saturation of the sites was higher in cellular extracts than in cytosols, pointing to the existence of receptor-estradiol complexes bound to nuclei. Our results suggest that the absolute number of occupied receptors depends upon the level of available cytoplasmic receptors as well as upon the level of tissue estradiol.

Differentiation of normal human mammary epithelial cells in culture: an ultrastructural study

An ultrastructural and cytochemical study of normal human mammary epithelial cells cultured from post-weaning breast fluids is described. Cells were examined at the time of plating and at intervals up to 28 days in culture. Three different stages in the morphological differentiation of these cells in vitro were observed: (1) the first stage was the formation of a monolayer of single cells, which occurred between days 1 and 10 in culture. The cells in this stage were not interconnected by junctional complexes and lacked Mg++- dependent ATPase activity in the plasma membranes, but did contain a large quantity of lipid and exhibited some secretory characteristics. (2) The second stage, occurring at 10 to 16 days in culture, was characterized by the formation of junctional complexes, the appearance of Mg++-dependent ATPase in the plasma membrane and a decrease in the number of dense bodies with peroxidase activity. (3) The third stage, occurring at 16 to 28 days in culture, was characterized by the formation of stratified layers of epithelial cells, which were interconnected by a larger number of desmosomes with numerous pleomorphic microfilaments. The Mg++-dependent ATPase activity in the plasma membrane was retained and the dense bodies with peroxidase activity were rarely observed at this stage. During the last seven days were prominent in the cells of the stratified layer. After 28 days in the culture, the cells began to round up and slough off the culture plate.

Ultrastructure of elastosis in scirrhous carcinoma of the breast

The stroma of scirrhous breast carcinoma frequently contains an abundance of material with the histologic staining properties of elastic tissue referred to as elastosis. In the present study, this lesion was found to correspond at the ultrastructural level to elastic fibers of various sizes and random orientation. These fibers displayed the two characteristic components, consisting of an amorphous core with a peripheral mantle of microfibrils. Interspersed among the elastic fibers were modified fibroblasts. These cells exhibited an irregular contour with numerous cytoplasmic processes and indentations. Their cytoplasm contained abundant rough endoplasmic reticulum, prominent Golgi complexes, and bundles of filaments. In the extracellular space, elastic fibers were often closely apposed to the plasma membrane of the fibroblasts. Carcinoma cells were also observed in the elastic tissue. It is postulated that fibroblasts, probably under an inductive influence from cancer cells, are the cells responsible for elastic production.

Intracytoplasmic lumina in breast carcinoma: a helpful histopathologic feature

Eelectron microscopy has disclosed the presence of intracytoplasmic lumina within breast cancer cells. These structures can be recognized with the light microscope by their sharp, round outlines and thick walls. Their identification in large numbers may provide additional support for the breast origin of a metastatic tumor. Three illustrative cases in which demonstration of intracytoplasmic lumina was diagnostically helpful are presented.

Cell surface differences in ducts from cancerous and noncancerous human breasts

The scanning electron microscope reveals structural differences between the apical microvilli of duct cells from cancerous and noncancerous human breasts. The alterations in the microvilli from carcinomatous breasts appear to be highly specific, to extend throughout the affected breast, and may be pathognomonic for this condition.

Ultrastructure of the human mammary gland. II. Postpartum lactogenesis

The history and fine structure of 7 human mammary glands were studied in the post partum. Widespread hypertrophy and hyperplasia of the mammary acini were observed accompanied by dilatation and engorgement of the lumen by milk. Loose strands of connective tissue surrounding the mammary lobules and ductules contained dilated, engorged vascular channels. The lactogenic epithelial cells displayed rich cytoplasm containing prominent layering stacks of rough endoplasmic reticulum closely related to the enlarged oval mitochondria, on occasion surrounding their entire circumference. Also noted were numerous ribosomes and polyribosomes. The markedly hypertrophied golgi apparatus revealed cisternae containing particulate electron dense material and vesicles with dense granules. The latter were frequently seen being discharged in the lumen devoid of limiting membrane. Abundant fat droplets were present in the basal and apical regions and "pinched off" into the lumen, apparently surrounded by a limiting membrane. The lactogenic cells were richly endowed with slender microvilli in their luminal pole and related to one another by cytoplasmic prolongations, desmosomes and tight junctions. The myoepithelium was stretched and thinned out toward the periphery of the acini between the lactogenic epithelium and the basement lamina. Abundant myofilaments were present in the myoepithelial cells. Pinocytotic vesicles were also present, although not very numerous, in both the lactogenic and the myoepithelial cells. In general the human mammary gland during lactopoiesis follows similar structural changes as those previously described in other mammals.

Apocrine metaplasia in cystic hyperplastic mastopathy. Histochemical and ultrastructural observations

A histochemical and ultrastructural investigation of apocrine cells in the human breast has been carried out. These cells showed strong oxidative enzymatic activity, large numbers of mitochondria and numerous infoldings of the basal plasma membrane. In these features, such cells resemble the normal apocrine gland cells. These observations support the view that this lesion is a metaplastic change in normal breast epithelium.

An ultrastructural study of normal human mammary epithelial cells in culture

The ultrastructure of normal human mammary cells cultured from post-weaning breast fluids is described. Cells from confluent monolayers in two week old cultures were studied. The epithelial nature of these cells was established by the demonstration of a well developed system of cell-to-cell interdigitation and numerous desmosomes. These cells also share with breast epithelial cells in vivo, polarity, with blunt short microvilli on the apical surface and an oriented arrangement of organelles in the basal and apical portions of the cells. The Golgi apparatus, which is the most highly developed organelle, is localized in the apical pole and contains substantial quantities of secretory material in the cisternae and vesicles. A variegated palisade of finely granular material mixed with tonofilaments is seen in the basal portion of the cells; many of these tonofilaments end in the terminal web of the desmosomes. The regular occurrence of these cells in breast fluids during the terminal phases of lactation suggests that their separation is a part of normal breast involution.

Autoradiographic localization of glycoprotein in human breast cancer cells maintained in organ culture after incubation with (3H)fucose or (3H)glucosamine

Explants of nine infiltrating duct carcinomas of the human female breast, maintained in organ culture, were exposed to the glycoprotein precursors, L-[3H]furcose and [3H]glucosamine, in order to determine the cellular distribution of newly synthesized glycoprotein as revealed by autoradiography with the light and electron microscopes. Explants were incubated with a single isotope for 2 hr, at which time some of the labeled explants were removed for autoradiographic analysis while the rest were transferred to nonradioactive medium for an additional 24 hr. After exposure to label for 24 hr, autoradiography with each isotope was similar and showed strong reactions over most tumor cells. The reactions were due to clumps of silver grains over intracytoplasmic lumina within single tumor cells and silver grains over Golgi saccules, cytoplasmic vesicles, lysosome-like bodies, lateral and basal plasma membranes, and microvilli. Extracellular ductular structures were also heavily labeled. At the later sampling time, Golgi saccules often showed a reduced reaction while the reactions over other organelles and intracellular and extracellular ductular structures remained strong. The observations suggest that in our in vitro system the tumor cells are metabolically active and complete the synthesis of the carbohydrate side chains of glycoproteins within the Golgi apparatus. From there, some of the newly synthesized glycoprotein appears to migrate to plasma membranes and lysosome-like bodies. Furthermore, our data support the notion that many duct carcinomas of the breast exhibit secretory activity by showing that some newly synthesized glycoprotein also appears to become products that are secreted into intracellular and extracellular ductular structures.