Granular endoplasmic reticulum

Fig. 7.11. Comparison of the fine structure of the membranes of the eggs of Hymenolepis diminuta and H. nana. Note in H. nana (in contrast to H. diminuta) (a) the embryophore is thin and incomplete - a feature which may facilitate hatching in the gut of the definitive host (b) there is an additional polar filament layer between the oncospheral membrane and the basal lamina. Gc, Golgi complex ger, granular endoplasmic reticulum /, lipid bodies m, mitochondria n, nucleus v, vacuoles. (After Fairweather Threadgold, 1981a Holmes Fairweather, 1982.)...

Smooth endoplasmic reticulum was observed only in M3 (33.8%) and Clara cells (49%). Granular endoplasmic reticulum was most abundant in serous (21%) and least plentiful in M4 (2.2%) cells (Mariassy and Plopper 1984). 

In the stumptail Macaca arctoides) and bonnet (Macaca radiata) monkeys, the cytoplasm of the Clara cells contained abundant mitochondria, a medium-sized Golgi complex, and a moderate amount of granular endoplasmic reticulum (Cast-LEMAN et al. 1975). In bonnet monkeys, the cells frequently contained round secretory droplets, which were homogeneously electron dense. Secretory droplets were less frequently observed in the non-ciliated bronchiolar cells of the stumptail monkey. The non-ciliated bronchiolar cells of the rhesus monkey (Macaca mulatto) were not observed to contain any secretory droplets. 

Xanthine oxidoreductase (EC 1.1.1.204) activity was detected in vesicles and occasionaUy on granular endoplasmic reticulum of rat Kupffer cells (Fre-... 

Figure 10.7 Ichthyosis hystrix type Curth-Macklin. (a) Unbroken concentric shell of tonofilaments (TS) surrounding the nucleus (N) and perinuclear cytoplasm with ribosomes and granular endoplasmic reticulum (ER) x 16 000. (b) 3 binucleate cells ( ) in the prickle cell layer (compare with Figure 10.6a) x4000...

Slender spindle-shaped fibroblasts are the commonest cell to be found in connective tissue. These cells, which manufacture matrix collagen and proteoglycans, have an elliptical nucleus and a cytoplasm which is contains extensive rough endoplasmic reticulum and Golgi apparatus, which are typical features of secretory cells. Mast cells are found widely within connective tissues and like fibroblasts these are secretory cells and characterized by a very granular cytoplasm. Almost as numerous as the fibroblasts and cytologically very similar to them, are macrophages, also called histiocytes or littoral cells. 

This is an interconnected network of flattened or spherical vesicles and tubules found in the cytoplasm of eukaryotic cells. These structures are enveloped by a membrane that separates the endoplasmic reticulum cavities or cisternae. The cisternae constitute a network of channels that go through the cytoplasm and regulate the transport of various cell products, generally to the exterior environment. In some cells the cisternae also serve as a storage area. There are two types of endoplasmic reticulum granular (or rough) and smooth. 

Other organelles include the rough endoplasmic reticulum, the subsurface cisternae, and the mitochondria. As in other cell types, the rough endoplasmic reticulum is the primary site of protein synthesis. In neurons, this granular organelle studded with ribosomes is also known as the Nissl substance, due to its chromophilic nature. It is highly developed in neurons and reflects the active protein synthesis that is constantly occurring in these cells. Few of the proteins synthesized at the Nissl bodies are secreted and the majority of them remain within the cell or are incorporated into the cell membrane. After ribosomal translation, many of the proteins are transported... 

A diagram of a section through a typical yeast cell is shown in Fig. 16.2. The cell is bounded by a wall which may bear one or several scars, and within the wall lies the cell membrane. Connected with the membrane and extending into the cytoplasm is the endoplasmic reticulum. This membranous system also appears to connect with the nuclear membrane which forms the boundary of the nucleus. Other organelles within the cytoplasm are the mitochondria and vacuoles, the latter often containing granular material. Lipid droplets may also be found in the cytoplasm. 

D) Mitochondrion with cristae, tubuli, and vesicles. Interstitial cell (Leydig cell) of the differentiated rat testis. Close spatial relationship with the endoplasmic reticulum (X). 1 36,000. (E) Mitochondrion with few cristae arranged in a typical way and fine granular matrix. Oocyte of a primary follicle (rabbit). 1 36,000. (F). Mitochondria with numerous tubuli and vesicles and with an electron dense matrix. Zona fasciculata of the suprarenal gland (adult rat). 1 36,000,... 

On the endoplasmic reticulum, one finds the granular ribosomes, containing about equal quantities of RNA and protein, in aggregates that form polysomes or ergosomes. 

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