Morphological study of cell organelles during development. I ‐ The nuclear sac and the endoplasmic reticulum on the rat nephron

Abstract

The maturation of the endoplasmic reticulum (ER) of rat kidney tubule cells was studied with an osmium impregnation technique. Thick sections (0.3-0.6 micron) of kidney tissue were made after a five-day impregnation with osmium tetroxide and examined by standard transmission electron microscopy at 80-100 kV. Studies were performed on rat foetuses from 18-21 days of gestation, on newborns, and on 2-20 day old animals. At the undifferentiated stage, only a small percentage of the tubule cells were impregnated; in these, the perinuclear sac was stained and a few nuclear pores were already seen. Rudimentary, but thick canalicular projections seemed to originate from the perinuclear sac and become more extensive with maturity. Flattened saccules appeared later and fenestrations were seen in proximal tubule cells only when they seemed to have reached their functional specialization. In some cells, only the Golgi apparatus was stained. In the distal tubule cells, there was also progressive formation of a network consisting first of canaliculi and later of saccules which were rarely fenestrated. The osmium impregnation technique appears to be useful as an index of the ER organization development.

Vasopressin modifies osmium impregnation of the endoplasmic reticulum in cultured kidney collecting duct cells

“…In fact, some cells clearly recall the ultrastructure of principal cells, whereas others have numerous mitochondria and a rich ER network typical of the intercalated cells [3,21]. 5) could also reflect various stages of cellular maturation in a homogeneous population of cells [6]. From these various observations, we propose that more than one cell type is present, but properties pertaining to each cell type may be shared; the cultivation could have modified cellular characteristics as reported for the MDCK and LLC-PK~ cell lines, where both cell lines possess properties of either the proximal or the distal tubule cells [10,11].…”

“…Osmium impregnation did not occur. In some cells, only the perinuclear membrane, showing the nuclear pores, is well stained (1) while in others, the ER is partially (!I) or fully (lid impregnated: such characteristics can be related to cell maturation (see [6]). Thickness, 0.3/~m; × 8,000.…”

“…The spatial organization of the endoplasmic reticulum (ER) has been recently characterized with the osmium impregnation technique in epithelial cells of both adult and fetal kidney [3,4,6]. A marked segmental polymorphism of the ER has been revealed.…”

Vasopressin modifies osmium impregnation of the endoplasmic reticulum in cultured kidney collecting duct cells

“…The various degrees of impregnation ( Fig. 5) could also reflect various stages of cellular maturation in a homogeneous population of cells [6].…”

A simple technique for staining of cell membranes with imidazole and osmium tetroxide.

“…With imidazole/osmium, all cells were consistently stained, whereas with osmic impregnation no reaction took place under the same normal conditions in some cells adjacent to others that were well impregnated. This phenomenon was observed in various tissues (e.g., proximal nephron, prostatic secretory cells, jejunum columnar cells, rat stem cells, toad bladder cells, flounder gut cells) and seemed to be associated with a histochemical property of the ER cisternae content relating to metabolic or hormonal cellular effects, rather than to a structural modification (5-7, [14][15][16][17][18]. The fact that the ER of all cells is stained with imidazole/osmium confirms this interpretation and further illustrates that the osmium impregnation technique constitutes a histochemical staining, as suggested earlier.…”