Abundant Smooth Endoplasmic Reticulum Research Articles

Ultrastructure of sensillum t 1 on the foretarsus of Acerentomon majus berlese (Protura : Acerentomidae)

The shape and ultrastructure of sensillum t 1 on the foretarsus of the proturan, Acerentomon majus Berlese have been described by means of scanning and transmission electron microscopy. Sensillum t 1 is a club-shaped structure, innervated by 3 sensory cells. Each cell is bipolar, with a single dendrite whose ciliary region has a 9-doublet structure. The terminal parts of 2 of the 3 dentrites, filled with many single microtubules, penetrate the cuticular hair, and in the apical swollen region of the sensillum divide into several dendritic branches. The third dendrite terminates as a tubular body at the base of the peg. A sheath-producing cell, a trichogen cell, and one tormogen cell envelop the dendrites. The latter cell has abundant smooth endoplasmic reticulum and produces a very peculiar secretion that is discharged in the space between the cuticular sheath around the dendrites and the cuticle of the hair. A palisade of tubules, 14nm high, is present beneath the cuticle of the apical part of the sensillum; at this level, the cuticle is perforated by numerous pores through which passes a dense material, forming a continuous layer over the cuticle. An olfactory function of sensillum t 1 has been proposed.

Histological, histochemical and ultrastructural studies on the interrenal and chromaffin cells of the fathead minnow, Pimephales promelas Rafmesque

Light and electron microscopic examination of fathead minnow head kidneys revealed that the interrenal and chromaffin cells were intermingled and always closely associated with the cardinal veins and their tributaries. Histochemical tests for lipids in the interrenal cells were positive, and two types of chromaffin cells were indicated by chromaffin reactions. Interrenal cells contained abundant smooth endoplasmic reticulum and mitochondria with tubulo‐vesicular cristae, characteristic of steroid‐producing cells. Only one interrenal cell type was found. Two types of chromaffin cells were present with differences in cytoplasmic density and in types of granules. In light cells, adrenaline granules were most common, and in dark cells noradrenaline granules predominated.

Spontaneous testicular neoplasm in mice with testicular feminization.

Testicular neoplasms occur spontaneously in androgen insensitive mice with testicular feminization (tfm/y); they are composed of Leydig cells, lipid-laden cells, fibroblastlike cells, and macrophages. The small Leydig cells in the periphery of the tumor are structurally similar to nontumorous tfm/y Leydig cells, whereas centrally located large Leydig cells contain numerous lipid droplets, mitochondria with tubular cristae, and abundant smooth endoplasmic reticulum. The lipid-laden cells exhibit a crescentic nucleus which is displaced toward the periphery of the cytoplasm by a large lipid vacuole. The fibroblastlike cells have a large amount of rough endoplasmic reticulum, lysosomes, free ribosomes, and lipid vacuoles. Macrophages are characterized by numerous layered and dense osmiophilic structures closely associated with crystalshaped bodies. An in vitro study shows that, in comparison with the normal testes, the tfm/y tumors produce significantly less testosterone but a larger quantity of androstenedione. Also, the tumors are capable of converting progesterone to estrone and estradiol-17 beta. The plasma level of testosterone is significantly lower in tumor-bearing animals than in normal littermates, but slightly higher than in the nontumorous tfm/y animals. Since the abnormal steroid enzyme activity is found in both tumor-bearing and nontumorous tfm/y mice, the basic cause of aberrations in sex steroid production appears to be genetic rather than the direct result of alterations in their Leydig cells.

ULTRASTRUCTURE OF GLANDULAR OVARIAN TRICHOMES OF CYPRIPEDIUM CALCEOLUS AND C. REGINAE (ORCHIDACEAE)

Trichomes on the orchid ovary are a possible site of synthesis and secretion of the floral scent. Scanning electron microscopy of these trichomes shows a bulbous cell on a two‐celled stalk. Thin sections of the tip cell revealed the morphology of an active, secretory cell with unusual coated vesicles in the extra‐cellular deposition. Abundant smooth endoplasmic reticulum (ER) aggregated beneath the plasma membrane in the apical region of the cell and the limited dictyosomes in the cell suggest direct secretion by ER. Numerous lipid droplets are present in the apical area. Plastids, found only in the basal region of this cell, are more round in profile than typical chloroplasts and contain only a few unstacked thylakoids and a limited membranous reticulum. In addition to the normal plastid envelope, a double layer of membrane (probably ER) is tightly appressed to each dense, starch‐free plastid. Highly specialized morphology and subcellular localization of organelles suggest the secretory nature of these trichomes.

Ultrastructure of Luteal Cells in Fully Formed and Regressing Corpora Lutea During Pregnancy and Lactation in the Marsupials Isoodon Macrourus and Perameles Nasuta.

Corpora lutea (CL) collected from 23 bandicoots (I. macrourus and P. nasuta), from day 5 of pregnancy (gestation 12.5 days) to day 53 of lactation (lactation c. 60 days), were examined with the electron microscope. The luteal cells of fully formed CL (from day 5 of pregnancy to day 44 of lactation) were large and contained spherical nuclei with distinct nucleoli. The amount of heterochromatin increased during the latter part of this period. The cytoplasm contained numerous lipid droplets and abundant smooth endoplasmic reticulum (SER). Granular endoplasmic reticulum (GER) was less common. Mitochondria were most numerous from day 16 to day 44 of lactation and some of them contained large osmiophilic inclusions. Several types of granules and inclusions were present in the cytoplasm. During pregnancy, small dense-cored granules were common in P. nasuta and sparse in I. macrourus. They were still present in small numbers during early lactation in P. nasuta but were absent throughout lactation in I. macrourus. A special type of cell junction associated with endoplasmic reticulum was present between the luteal cells in P. nasuta but not in I. macrourus. The luteal cells of regressing CL on days 48, 50 and 53 of lactation were markedly reduced in size, with small irregularly shaped nuclei containing clumps of heterochromatin and indistinct nucleoli. The cells still contained numerous lipid droplets, and osmiophilic inclusions were still present in some of the mitochondria, which were reduced in number (and absent in the animal at day 50). Lancet-shaped spaces, which probably initially contained cholesterol crystals extracted by solvents during processing, were present in some of the regressing luteal cells. Organelles, including SER and GER, were either sparse or unrecognizable in luteal cells at advanced stages of regression. In general, the ultrastructural features of the luteal cells in fully formed and regressing CL of bandicoots were similar to those described in active and regressing CL of eutherian mammals.

Functional significance of interrenal cell zonation in the adrenal gland of the duck (Anas platyrhynchos)

Slices of whole adrenal gland tissue, incubated in vitro in the presence of ACTH for 1 h and 2 h produced corticosterone and aldosterone in constant ratio (16:1). Tangential slices taken from the region immediately below the connective tissue capsule and slices taken from deeper regions of the gland consisted primarily of cells conforming to the distinct structural characteristics of the subcapsular zone (SCZ) and inner zone (IZ) tissues respectively. When samples were incubated in the presence of ACTH for 1 h and 2 h, the interrenal cells of the SCZ produced relatively more aldosterone than cells taken from the IZ of the gland. The corticosterone: aldosterone ratio for the IZ after 1 h (68:1) and after 2 h (102:1) were ten times greater than the ratios for the SCZ after 1 h (7:1) and after 2 h (10:1). The SCZ slices were not more than 60 cells thick and consisted of cells arranged in cords. These cells contained irregular nuclei, mitochondria with shelf-like cristae and a moderate abundance of smooth endoplasmic reticulum. In contrast, the production of large amounts of corticosterone by the cells of the IZ was associated with tissue containing more vascular space than the SCZ and the cells contained large round nuclei surrounded by an abundance of smooth endoplasmic reticulum and the mitochondria had tubular rather than shelf-like cristae.

Hepatic Glucose-6-Phosphatase Activities and Correlated Ultrastructural Alterations in Hepatocytes of Diabetic Rats

Cell fractionation, enzyme analysis, and electron microscopy were used to study the effects of streptozotocin-induced diabetes and insulin replacement on liver structure and function. In liver homogenates from diabetic rats, glucose-6-phosphatase (G-6-Pase) activity was stimulated about 2 1/2-fold over that found in normal animals. Analyses of isolated rough and smooth microsomes from diabetic rats for G-6-Pase activity showed a fourfold increase in the smooth microsomes and a small increase in enzyme activity in rough microsomes when compared with these fractions from control animals. Associated with the increased enzyme activity was a reduction in liver glycogen. Insulin treatment of the diabetic rats caused a fall in homogenate G-6-Pase levels to approximately normal values and stimulated the accumulation of hepatic glycogen. Administration of insulin to these animals also caused a decrease in G-6-Pase activity, which was most pronounced in the smooth microsomes. Studies with the electron microscope revealed ultrastructural alterations in livers of the diabetic rats, which were most striking in the periportal region of the lobule. Periportal hepatocytes from diabetic rats displayed dispersed particles of glycogen separated by cytoplasm rich in SER rather than dense masses of glycogen with little SER, as is characteristic of these cells in normal animals. Centrilobular cells from the diabetic animals displayed some disorganization of the RER and a dispersed pattern of glycogen with abundant SER, similar to the pattern found in these cells from normal animals. After insulin treatment the periportal cells appeared normal morphologically, whereas the centrilobular hepatocytes displayed regions of both dense masses and dispersed glycogen. In the glycogen masses, little SER was found; however, in the areas of dispersed glycogen particles, an abundance of this organelle was evident. We conclude from these studies that diabetes causes an increase in amount of hepatic smooth endoplasmic reticulum (SER), especially within periportal hepatocytes. The results of cell fractionation indicate that membranes of the smooth endoplasmic reticulum are enriched in G-6-pase. We interpret these results to indicate that diabetes causes hepatocytes to form additional smooth endoplasmic reticulum with specialized membranes, at least with respect to G-6-Pase. It is suggested that this cellular specialization is a response of the hepatocyte to the diabetic state, namely, a demand for increased hepatic glucose production and release into the blood stream, thus contributing to the hyperglycemia characteristic of this disease. Insulin administration to the diabetic animals reverses the above alterations.

An ultrastructural and clinical study of theca and granulosa cell tumors.

To establish the cell type responsible for the production of estrogens in an ovarian tumor, seven thecomas, three granulosa cell tumors and one fibroma were studied with electron microscopy. The secretion of estrogens by the tumor was determined by measuring the plasma levels of estrogens in the ovarian and cubital veins of some patients and examining the histology of the endometria. Polygonal cells with abundant smooth endoplasmic reticulum (SER) at the ultrastructural level were found in the tumors of patients with clinical signs of hyperestrogenism. It is likely that these cells are the site of steroidogenesis, which is known to be reflected by SER in the cells of the human corpus luteum.

Obsrvations on the Fine structure of the Testicular Interstitial Cells in the Camel (Camelus Dromedarious)

Testicular interstitial cells of the camel are polygonal in shape with abundant smooth endoplasmic reticulum (SER) occurring as a network of tubules. Elements of a welldeveloped Golgi complex are seen in many parts of the cytoplasm. There is a moderate number of mitochondria with predominantly lamellar cristae and dense intramitochondrial granules. Lipid droplets vary in size and number from cell to cell. Lysosomal bodies are commonly encountered in the cytoplasm. Other cytoplasmic constituents include microfilaments, peroxisomes, a few pathches of rough endoplasmic reticulum and occasional glycogen particles.The functional significance of these observations is discussed in relation to comparative observations on other vertebrates as in relation to histochemical findings on camel testis. There is sufficient evidence to indicate that the interstitial cells in the camel testis resemble interstitial cells of other vertebrates.Letdig cells during the non‐breeding season possess abundant lipid droplets, large lysosomal bodies together with narrow cisternae of SER, i.e. features of inactivity. Maximal activity is seen during the rutting season and it is suggested that this activity correlates with the of seminiferous epithelium and accessory sex glands.

Morphology of the granular secretory glands in skin of poison-dart frogs (Dendrobatidae)

The granular glands of nine species of dendrobatid frogs were examined using light and electron microscopy. The glands are surrounded by a discontinuous layer of smooth muscle cells. Within the glands proper the secretory cells form a true syncytium. Multiple flattened nuclei lie at the periphery of the gland. The peripheral cytoplasm also contains mitochondria, rough surfaced endoplasmic reticulum, the Golgi apparatus, and an abundance of smooth endoplasmic reticulum. Centrally, most of the gland is filled with membrane-bound granules surrounded by amorphous cytoplasm. Few other organelles are found in this region. Early in the secretory cycle, the central part of the gland is filled with flocculent material which appears to be progressively partitioned off by membranes to form the droplet anlage. As granules form, the structure of the contents becomes progressively more vesicular. Dense vesicles, which bud off from the Golgi apparatus, fuse with the granular membrane during the development of granules, and might contain enzymes involved in toxin synthesis. The granules at this point resemble multivesicular bodies. Their structure is similar in all species of dendrobatid frogs even though the different frogs secrete substances of different chemical structure and toxicity.

Unusual association of ‘chloride cells’ with another cell type in the skin of the glass catfish, Kryptopterus bicirrhis

A previously undescribed association of typical ‘chloride cells’ and a second distinct cell type are observed in the skin of the freshwater glass catfish, Kryptopterus bicirrhis. The second cell type is similar to the chloride cell in that it contains abundant smooth endoplasmic reticulum and mitochondria. However, its small size and greater electron density suggest it is a ‘resting’ or non-functional chloride cell. Together these two cells form a crypt which leads to the skin surface. They may constitute a specialized structure involved in the passage of ions across the skin of these fish.

Ovarian Interstitial Gland Tissue and Serum Progestin Levels during the First Periovulatory Period in the Mated Rabbit1

In order to determine the morphology of the interstitial gland tissue and possibly correlate these findings with the serum levels of 20α-dihydroprogesterone, mature New Zealand virgin rabbits were each assigned to 1 of 4 groups: estrous controls; 5 h; 10 h; and 2 days after mating. Data indicated that the amount of interstitial gland tissue in the ovaries varied between rabbits regardless of the group to which they were assigned. The virgin estrous rabbits generally had minimal amounts of interstitial gland tissue and low levels of serum 20α-dihydroprogesterone. Ovaries of some rabbits had an abundance of interstitial gland tissue which was composed mainly of large cells and had an output of 20α-dihydroprogesterone greater than those ovaries with a lesser amount of interstitial gland tissue. In those ovaries where an abundance of interstitial gland tissue was present, some morphological changes were seen between the 3 periovulatory stages which can be related to variations in 20α-dihydroprogesterone. At 5 h after mating, the ovaries with large amounts of interstitial gland tissue had cells with an abundance of smooth endoplasmic reticulum and serum 20α-dihydroprogesterone levels were elevated. At 10 h after mating, some follicles had ovulated and the large interstitial gland cells displayed an increase in numbers of lipid droplets which was accompanied by a decrease in 20α-dihydroprogesterone. At 2 days after mating, most large interstitial gland cells had an accumulation of large lipid droplets and progestin levels continued to decrease.

Possible relationship between the activity of the adrenal gland and the subcommissural organ in the lizard Lacerta s. sicula raf.

In order to study the possible functional relationship between the adrenal gland and the subcommissural organ (SCO) in the lizard Lacerta s. sicula Raf., ACTH was administered to some specimens of this species in January when both the adrenal gland and the subcommissural organ have a very low activity. In comparison to untreated controls, the adrenals of animals treated with ACTH showed clear signs of stimulation, presenting enlarged blood vessels, very few lipid droplets, numerous polymorphic mitochondria and abundant tubular smooth endoplasmic reticulum. In addition, a distinct increase in secretory material was observed in the subcommissural cells of specimens treated with ACTH. These cells showed large cisternae of the rough endoplasmic reticulum filled with granular material in the basal region, numerous secretory granules of two types in the paical region and a reduced number of microvilli on the free cell surface. These findings, together with the results of preceding studies, lead the authors to the consideration that steroid hormones might play a role in the regulation of the secretory activity of the SCO.

The ultrastructure ofImpatienspollen tubes

SummaryThe pollen tube of Impatiens contains numerous vesicles, abundant smooth endoplasmic reticulum, mitochondria and dictyosomes. Ribosomes are few in number and there is only a small amount of rough endoplasmic reticulum. There are two types of vesicles. Firstly, electron-dense vesicles containing polysaccharides, which are most numerous at the tube apex and are interpreted as secretory vesicles. Secondly, electron-transparent vesicles which are most numerous in the proximal part of the tube and are interpreted as a specialized vacuolar system. The electron-dense vesicles apparently are formed by SER cisternae as terminal swellings. The SER in turn is continuous with the golgi-apparatus.

Androgen producing adrenocortical carcinoma

Two cases of androgen secreting adrenocortical carcinoma have been described by light and electron microscopy. The histological and ultrastructural features of the tumour cells were similar to those of compact cells of zona reticularis and to those described in virilizing adenomas. They possess numerous mitochondria with lamellar and tubular cristae, abundant smooth endoplasmic reticulum, lipofuscin bodies and scanty lipid. Irregularly shaped, crenated mitochondria, with outpouchings of the outer limiting membrane have also been observed. The clusters of neoplastic cells were surrounded by basement membrane which demonstrated a focal discontinuity, probably reflecting malignancy of the tumours. Hyperplasia of smooth endoplasmic reticulum and the presence of outpouchings of the mitochondrial outer limiting membrane might be the morphological manifestation of endocrine activity of the tumours.

The ultrastructure of testicular tumours in the dog: II. Leydig cells and Leydig cell tumours

The ultrastructural appearance of testicular Leydig cells in healthy dogs as well as canine Leydig cell tumours is described. The cells of most Leydig cell tumours (10 out of 13) showed the typical characteristics of normal Leydig cells: abundant smooth endoplasmic reticulum, mitochondria with tubular inner structures and numerous small and larger granules, many lipid droplets, intracytoplasmic filaments, and oval nuclei with distinct nuclear pores. In only 3 out of 13 cases were cells with scarce endoplasmic reticulum, polymorphous nuclei, and mitochondria only of the christae type observed. In such tumours however, single cells also showed the typical features of Leydig cells.

Electron microscopy of a feminizing leydig cell tumor of the testis

The ultrastructural characteristics of a feminizing interstitial (Leydig) cell tumor of the testis were compared with those of normal Leydig cells and with the findings described in 10 published cases of Leydig cell tumor. The neoplastic Leydig cells superficially resembled normal Leydig cells. Similarities included abundant smooth endoplasmic reticulum, lipid, and microbodies. Contrastingly, Reinke crystalloids and paracrystalline inclusions were absent and lipochrome pigment and lysosomes very rare. The nuclei were large and contained enlarged, often multiple, nucleoli. The nuclear membranes tended to be irregular and undulating. Cytoplasmic membranous whorls and myelin figures were conspicuous. Fairly homogeneous fibrous septa were evident between single and grouped tumor cells. Despite several individual variations, there is a general resemblance between the neoplastic Leydig cells in this patient and those previously reported. No distinguishing ultrastructural characteristics were discerned between feminizing and virilizing Leydig cell tumors.

Ultrastructural evidence for aldosterone- and corticosterone-secreting cells in the adrenocortical tissue of the American bullfrog ( Rana catesbeiana)

Two types of adrenocortical cells were observed after hypophysectomy or dexamethasone treatment: (1) a regressed cell characterized by a reduction of the smooth endoplasmic reticulum, a lack of osmiophilia of the lipid, and a tendency for the lipid droplets to coalesce; (2) an active cell characterized by abundant smooth endoplasmic reticulum, osmiophilic lipid and individual lipid droplets. Treatment with mammalian ACTH, metopirone, or spironolactone, or maintenance of the animals in distilled water all resulted in adrenocortical cell stimulation as evidenced by deeply osmiophilic lipid, extensive smooth endoplasmic reticulum, abundant polysomes, a pronounced perinuclear space and distinct nuclear pores. In addition, animals maintained in distilled water or treated with spironolactone had many cells with lamellar mitochondrial cristae. In contrast, the adrenocortical cells of control animals and those subjected to other treatments, generally had vesicular or tubular cristae. The ultrastructural observations are consistent with published physiological data on the anuran pituitary-adrenocortical axis and indicate that corticosterone and aldosterone are secreted by different cells in the bullfrog adrenocortical tissue.

Bilateral Testicular Tumors in Congenital Adrenal Hyperplasia

A 22-year-old male with bilateral testicular tumors and the 21-hydroxylase variety of congenital adrenal hyperplasia (CAH) was studied. Preoperatively, on his usual glucocorticoid regimen, his urinary pregnanetriol excretion was increased (8.0-23.5 mg/day), serum LH and FSH were normal to increased (14.3-28.7 mIU/ml and 13.2-19.5 mIU/ml, respectively) and testosterone (T) was normal to decreased (176-600 ng/dl). At surgery, testicular vein concentrations of 17-alpha-hydroxyprogesterone (17-OHP) and adnrostenedione (delta) were increased (30.1 mug/dl and 38.3 mug/dl respectively) while T was decreased (1,503 ng/dl); a positive peripheral vein--testicular vein gradient was not seen for these steroids. Following injection of 10 U of crystalline ACTH into the testicular artery; testicular vein concentrations of 17-OHP, delta and T increased to 729 mug/dl, 2,390 mug/dl and 9,660 ng/dl respectively. Microscopic examination of the testes revealed multinodular tumors composed of polygonal or rounded eosinophilic cells, arranged in cords, nests and clusters. The tumors extended from the hilus and compressed the adjacent testicular tissue. Electron microscopic examination of the tumors showed features, common to steroid-secreting tissues, with abundant smooth endoplasmic reticulum in close proximity to mitochondria which was moderate in number. The adjacent testicular tissue was composed of immature tubules with normally developed Leydig cells in the interstitial tissues. From these data and a survey of previous works, it was postulated that these tumors were dependent upon ACTH for growth and steroid secretion. In view of the high serum LH concentration seen in association with incomplete suppression of adrenal steroid secretion in this study and the association of evidence of gonadotropin secretion with testicular tumors in other CAH patients, LH may also have contributed to the growth of these tumors.

Smooth Endoplasmic Reticulum in Rat Hepatocytes during Glycogen Deposition and Depletion

Publisher Summary This chapter discusses the role of smooth endoplasmic reticulum (SER) in hepatic glycogen metabolism. Data are reviewed from several types of experiments which allowed study of the participation of SER in glycogenesis and glycogenolysis. SER functions in both synthesis and degradation of hepatic glycogen. The development of SER follows a cyclic pattern: proliferation of the organelle occurs during early stages of glycogen deposition and remains associated with glycogen particles throughout all stages of deposition of the carbohydrate until high or maximum quantities of glycogen are accumulated by the cell. At this point SER decreases to very low levels in hepatocytes. During depletion of glycogen, SER again proliferates and shows a close relationship to the remaining glycogen particles in hepatocytes. An abundance of SER is present in hepatocytes throughout all stages of glycogen depletion until the cell is devoid of glycogen granules. At this point SER decreases to low values but nevertheless is present in small quantities. Much attention should be given in future work to obtaining pure SER membranes from livers of rats under precisely controlled metabolic conditions and assaying these membranes for various enzymes involved in glycogen metabolism.