Sebaceous gland differentiation. I. Separation, morphology and lipogenesis of isolated cells from the mouse preputial gland tumor.

Single cell suspensions have been prepared, by enzyme digestion, from the mouse preputial gland tumor and separated by flotation centrifugation into populations of different buoyant densities. These populations of cells have been shown by morphological, chemical and biochemical criteria to be in different stages of maturation. Some properties of the separated cells are described.

Culture of cloned cells from the mouse preputial gland tumor ESR 586.

Cells from the mouse preputial gland tumor ESR 586 have been cultured and cloned. Trypsin-ethylenediaminetetraacetate was used to obtain single cells. The cells are grown in a modified CMRL-1415 medium supplemented with 10% fetal calf serum. Clones tend to fall into two classes: Class 1, those that undergo morphological differentiation in liquid medium to form round bodies filled with lipid vaculoes; and Class 2, those that do not differentiate. Preliminary studies on the control of differentiation in Class 1 clones suggest that a minimum cell density is required before differentiation takes place. Analysis of the lipids from differentiating and nondifferentiating clones reveals the presence of sebaceous-type lipids in differentiating clones only. No requirement for testosterone was found for these cells.

Ultrastructural changes and viral morphogenesis during the growth of the mouse preputial gland tumor ESR 586.

A study was undertaken to observe morphological changes and viral morphogenesis during the growth of the mouse preputial gland tumor ESR 586. The acinar cells of the normal preputial gland have an extensive agranular endoplasmic reticulum and Golgi apparatus and large lipid droplets. No viral particles are present. During tumor growth, and numerous lipid droplets never attain the size of those found in the normal gland. There is a decrease in the Golgi apparatus and agranular endoplasmic reticulum and an increase in the rough endoplasmic reticulum which could reflect a change in composition of tumor secretory product from the normal gland. Indeed, there is a decrease in triglycerides as the tumor ages and an increase in the sterol esters and waxes. In addition, intracisternal A-particles are observed budding from thickened endoplasmic reticulum membranes. Thickening of these membranes occur early in A-particle formation. One side of the membrane is first thickened while the opposing membrane appears is first thickened while the opposing membrane appears morphologically unaffected. The thickening of the affected membrane is initially confined to the outer (cytoplasmic) face of the membrane. In the older tumor, both opposing membranes of the reticulum are thickened and can assume an elongated whorled pattern.

Demonstration of gap junctions by lanthanum in the vitamin A acid-treated skin tumor, keratoacanthoma.

In normal rabbit epidermis or in the untreated skin tumor, keratoacanthoma the usual cell junction is the desmosome. Gap junctions are very sparse. The extracellular tracer material, lanthanum nitrate was used to confirm the definite identification and increase of gap junctions in the vitamin A acid-treated keratoacanthoma. Without the use of lanthanum, the gap may not be always apparent in conventional thin sections and can be confused with the zonula occludens.

Mucous metaplasia and gap junctions in the vitamin A acid-treated skin tumor, keratoacanthoma.

Desmosomes are the usual cell junctions found in normal rabbit epithelium as well as in the untreated keratoacanthoma. This study reports the finding of a second cell junction, the gap junction, when epithelium, normal or tumorous, is subjected to topical applications of vitamin A acid. The gap junction forms early in mucous metaplasia (after 2 days of application of vitamin A acid) and appears before the gross appearance of mucus. The presence of the gap junction occurs when there is an increase in the rough-surfaced endoplasmic reticulum and Golgi cisternae and vesicles. It is possible that the early appearance of the gap junction facilitates and mediates the mucous metaplasia. This suggestion is strengthened by the fact that the gap junction, once present in the mucus-producing tumor, is sparse when the tumor reverts back to the dry, keratotic condition upon cessation of vitamin A acid applications.