Autophagy-related vacuoles in mouse gallbladder epithelium

The mouse gallbladder epithelial cells contain very heterogeneous vacuolar population. In an attempt to classify these vacuoles we identified NADPase and TPPase activity as well as the location of HRP which is used as the endocytotic marker. The results of the present study show that the vacuoles can be classified into three categories: (1) the vacuoles predominantly containing loose membrane coils related to the nascent autophagic vacuoles, (2) vacuoles containing densely packed membranes and exhibiting a positive HRP reaction, indicating the convergence of endocytotic and autophagic pathway, and (3) vacuoles composed of degraded membrane structures and containing the reaction product of NADPase activity, showing that the fusion of the lysosomes with the autophagosome-endosome took place. The highly developed cis, medial and trans Golgi compartments reflect the biosynthetic and endocytotic activity of the gallbladder epithelium.

In vitro cytochemical studies of the golgi apparatus of pancreatic acinar cells exposed to drugs that inhibit the transport of membranes and proteins

In a preceding article, we described alterations occurring in rat pancreas acinar cells at successive post-mortem (PM) intervals. In ultra-thin sections from samples obtained from 0.5, 1, 2, 4, 8 and 12 h, we observed in the Golgi apparatus the appearance of an anomalous membrane bound structure. Such structures are formed by tubules and vesicles that we have called tubular vesicular structure (TVS), and they are frequently located in the position corresponding to the 4th cisterna of the Golgian cisternal pile. Lobules of rat pancreas, incubated in vitro with metabolic inhibitors (such as antimycin A, sodium fluoride, sodium azide and potassium cyanide), were processed in order to be compared with the PM samples of the rat acinar cells. In sliced pieces of lobules, acid phosphatase (AcPase) and tiaminopirophosphatase (TPPase) activity were evaluated. Except for the potassium cyanide treatment, we frequently observed the TVS located at the position corresponding to the 4th cisternae (similar to those observed in the PM acinar cells). These TVS's are predominantly TPPase positive. Based on this result and the fact that the TVS's are surrounded by a membrane (as confirmed by the freeze-fracture replica results) with no structural elements inside, they seem not to correspond to autophagosomes. The TVS's, observed either at PM consecutive times or incubated with metabolic inhibitors, seem to be structures formed in response to ATP deprivation. In 0,5 h PM cells and in cells incubated for 30 and 60 min with metabolic inhibitors, the subcellular structures reacted for AcPase in the rigid lamellae, CV and lysosomes.

Effects of brefeldin A on autophagy in cultured rat fibroblasts

Effects of brefeldin A on cellular autophagy were studied in cultured rat fibroblasts. Brefeldin A inhibits the activation and membrane-binding properties of most ADP-ribosylation factors and causes the redistribution of Golgi proteins into the endoplasmic reticulum. Immunofluorescence and enzyme cytochemical methods revealed the disappearance of the Golgi apparatus and trans-Golgi network during the brefeldin A incubation. The volume fractions of autophagic vacuoles increased about threefold in cells treated with brefeldin A for 4 h and about sixfold in serum-deprived cells as compared with controls. When cells were first treated with brefeldin A for 1 h and were then deprived of serum and treated with brefeldin A for 3 h, the volume fraction of autophagic vacuoles increased about 4.5-fold as compared with untreated cells. The results showed that brefeldin A is unable to prevent serum deprivation-induced accumulation of autophagic vacuoles and that brefeldin A even when acting alone increases the volume fraction of autophagic vacuoles. It was concluded that an intact Golgi apparatus and trans-Golgi network are not essential for the formation of autophagic vacuoles. It seems also probable that ADP-ribosylation factors are not needed when vacuoles are formed.

Apical tubules in marginal cells of the differentiating stria vascularis

BACKGROUND

Apical tubules (ATs) in marginal cells (MCs) of the stria vascularis appear in limited stages of differentiation of the MCs, but their origin and roles remain uncertain. The present study was designed to solve the problem of whether the ATs are intracellular compartments derived from the Golgi apparatus (GA).

METHODS

The cochleae of Wistar rats at ages of postnatal days 1, 3, and 5 were prepared for electron microscopy and cytochemistry using thiamine pyrophosphatase (TPPase) and coenzyme A phosphatase (CoA-Pase) as marker enzymes of trans Golgi cisterns and fluorescent labelled lectin, griffonia simplicifolia agglutinin-I (GS-1).

RESULTS

The ATs appeared in the apical cytoplasm of the MCs between postnatal days 1 and 5. Reaction products of TPPase and CoA-Pase activities were localized in the trans-Golgi cisterns and the ATs, which were occasionally in a close apposition to the GA. The reaction was found along the apical plasma membrane of the MCs only in case of TPPase. Heavy reactions to GS-1 were seen in the supranuclear region as well as along the apical plasma membrane of the MCs.

CONCLUSIONS

The present ultrastructural and cytochemical studies indicate that the ATs, which appear in the MCs at limited perinatal stages, originate from the trans-Golgi cisterns. These ATs may be involved in the apical plasma membrane supply for the differentiation of the MCs prior to the generation of EP.

Ultrastructural localization of activity of phosphatases by low temperature incubation of unfixed cryostat sections

In the present study, we demonstrate the activity of several phosphatases ultrastructurally in long-term (up to 24 months) cold-stored (-80 degrees C) rat tissues. Phosphatase activity was histochemically studied with the use of unfixed cryostat sections in combination with low temperature (4 degrees C) incubation conditions in order to prevent inactivation of enzyme activity and to limit the loss of ultrastructure. 5'-Nucleotidase activity was observed at plasma membranes, mainly at bile canalicular membranes of hepatocytes in liver. Thiamine pyrophosphatase activity was detected not only in trans side cisternae but also in medial and cis side cisternae of Golgi complexes in the parotid gland. Glucose-6-phosphatase activity was localized in endoplasmic reticulum as well as at the outer membrane of the nuclear envelope. Acid phosphatase reaction product was found in lysosomes. Furthermore, the localization patterns of 5'-nucleotidase and thiamine pyrophosphatase activity were compared with those obtained after different fixation procedures such as immediate chemical fixation of tissues or fixation of tissues after freezing and thawing. The results showed similar localization patterns of these enzymes after the different pretreatments. However, with respect to the ultrastructural morphology, some damage was observed in unfixed material after incubation. It can be concluded that the procedure described here enables ultrastructural localization of activity of phosphatases in long-term cold-stored tissues. This procedure will be useful for a retrospective study on archival material when histochemical parameters are needed.

[Ultracytochemical study of activity of various phosphatases during early postmortem period in experimental animals]

The activities of acid phosphatase (AP), glucose-6-phosphatase (G-6-P), and thiamine pyrophosphatase (TPP) were assayed in the epithelial cells of the main bronchi and hepatocytes of rats within 1 to 5 hours after their death. In the postmortem period, some enzymes (AC, G-6-P) retained their activity while the others (TPP) were inhibited. Furthermore, there were unusual intracellular sites of AP reaction products.

Dose-dependent effects of chloroquine on secretory granule formation in the melanotroph

Chloroquine diverts secretory peptides from the regulated to the constitutive secretory pathway. The exact site and mechanism of the effect are not known. We studied the effect of increasing doses of chloroquine on the morphology of cultured melanotrophs from the rat pituitary. 40 microM chloroquine for 2 h, which perturbs intracellular pH gradients in melanotrophs without affecting secretion, caused swelling of a subpopulation of immature secretory granules. 200 microM chloroquine for 2 h, which diverts secretory peptides from the regulated to the constitutive pathway in the AtT-20 cell line, caused pronounced swelling of immature secretory granules, vacuolization of the trans-Golgi region and the appearance of myeloid bodies and multivesicular bodies in the cytoplasm. Golgi stacks were retained and Golgi cisternae only slightly dilated at both chloroquine concentrations. Mature secretory granules were not affected. Cationized ferritin was internalized and transported to the trans-Golgi region in the presence of 40 microM chloroquine while 200 microM chloroquine arrested internalised ferritin in peripheral multivesicular bodies. The study shows a heterogeneous effect of lower doses of chloroquine on immature secretory granules, providing a tool for studies on the relationships between condensation, acidification and peptide processing during granule formation. Chloroquine of 200 microM caused morphological changes typical for chloroquine toxicity and arrest of endocytic traffic.

Three dimensional observation of whole mount cultured cells stained with histochemical reactions by ultrahigh voltage electron microscopy

Thick biological specimens prepared as whole mount cultured cells stained with histochemical reactions, such as thiamine pyrophosphatase, glucose-6-phosphatase, cytochrome oxidase, acid phosphatase, DAB reactions demonstrating specific cell organelles such as Golgi apparatus, endoplasmic reticulum, mitochondria, lysosomes, peroxisomes and pinocytotic vesicles, were observed by ultrahigh voltage electron microscopy at accelerating voltages of 400-1000 kV producing stereo-pairs. As a result, those cell organelles were observed 3-dimensionally and the relative relationships between these organelles demonstrated.

The Golgi apparatus and acid phosphatase-negative cisternal portions of the trans-Golgi network: ultrastructural and cytochemical studies of secretory epithelial cells in the rat lateral prostate

Ultrastructural and enzyme-cytochemical studies were performed on the Golgi apparatus in secretory cells of the lateral prostate of normal adult rats using serial ultra-thin sections. In the trans-Golgi area, a unique membrane complex composed of tubular portions and cisternal portions showing a rigid appearance is found. This corresponds to the GERL (Novikoff 1964) or the trans-Golgi network (Griffiths and Simons 1986). From their structural similarities, the cisternal portion found in this study is considered to be the same structure as the plate-like cisterna reported by Inoue and Kurosumi (1989). As we reported previously (Kimura and Ichihara 1985), there are at least two types of acid phosphatase (AcPase) in secretory cells of the rat lateral prostate: one is located only in the structural components involved in their secretory functions and reacts readily with naphthol AS-BI phosphate; the other is a lysosomal type, which reacts well with beta-glycerophosphate. Lysosomal AcPase activity demonstrated by Gomori's method (1952) was found in a few middle- to trans-Golgi cisternae and in lysosomes. The AcPase detectable with Gomori's method and thiamine pyrophosphatase seemed to exist in part in the same cisterna on the trans side. With Robinson and Karnovsky's method (1983) for lysosomal AcPase, however, the reaction products were found only in lysosomes that were occasionally tubular in shape. On the other hand, any activity of AcPases tested could not be detected in the cisternal portion with the rigid appearance. Thus, in secretory cells of the adult rat lateral prostate in normal condition, it is considered that the cisternal portion of GERL, or the trans-Golgi network, has no relation to the processing and/or transport of AcPases.

Ultracytochemical studies on Trichomonas hominis

The results of ultracytochemical studies on Trichomonas hominis showed that ACPase and CMPase were mainly located in the mature face sacs of the primary lysosomes, digestive vacuoles, as well as in the parabasal body. TPPase and NADPase were found in the saccules at the mature face and the intermediate saccules of parabasal body respectively. This study revealed that T. hominis had well-developed parabasal bodies. Negative COase and catalase reactions indicated that T. hominis lacked both mitochondria and microbody. Hydrogenosome was stained well with the Ur-Pb-Cu impregnation technique.

Ultrastructural and cytochemical studies of the effects of prolactin on the lateral prostate and the seminal vesicle of the castrated guinea pig

Administration of ovine prolactin to castrated guinea pigs for 2 weeks induced hypertrophy of secretory cells in the lateral prostate when compared with the castrated controls. This was accompanied by an apparent increase in the number of profiles of granular endoplasmic reticulum and well developed Golgi complexes with dilated cisternae. An increase in the number of low-contrast electron-dense secretory granules was observed 4 weeks after prolactin treatment. In the seminal vesicle, dilatation and degranulation of granular endoplasmic reticulum and an apparent decrease in the number of secretory granules were observed 4 weeks after prolactin administration. Following castration and 2 weeks after prolactin treatment, thiamine pyrophosphatase (TPPase)-reaction product was mainly confined to 1-2 trans cisternae of the Golgi complexes in secretory cells of the lateral prostate and the seminal vesicle. In both glands, a reduction of TPPase activity was observed 2 weeks following prolactin administration, and the reaction product was totally absent after prolonged treatment for 4 weeks. The present study has provided morphological evidence that prolactin is capable of stimulating the secretory function of the lateral prostate while exerting some inhibitory effects on the seminal vesicle of the castrated guinea pig. In both glands, TPPase activity, and hence the process of glycosylation was inhibited after prolactin administration. The results from radioimmunoassay indicated that the action of prolactin on these glands could be a direct effect and not mediated through testosterone.

Presence of Golgi remnant membranes in the cytoplasm of brefeldin A-treated cells

Brefeldin A (BFA) rapidly blocks secretion, induces disassembly of the Golgi complex and causes a redistribution of Golgi components into the endoplasmic reticulum (ER). In addition to these effects on the exocytotic pathway, BFA has been shown to induce fusion of endosomal membranes with the trans-Golgi network in some cell types. To better understand the mechanism through which BFA disrupts the exocytotic traffic, we have examined its effects on the ultrastructural organization of the Golgi complex. Within minutes of exposure to BFA, the Golgi cisternae were fragmented into a number of small tubules and vesicles, many of which had a non-clathrin coat on their cytosolic surface. In addition, a complex structure consisting of anastomosing tubules and associated vesicles appeared in the cytoplasm of cells incubated with BFA for 10 min or longer. These tubular networks were permanent, distinct structures separated from the ER cisternae. They contained cis, middle, and trans Golgi proteins as well as the lipid analogue C5-DMB-ceramide. Furthermore, secretory proteoglycans en route through the Golgi were retained in the lumen of the tubular networks. As judged by the endocytosis of cationized ferritin, endosomes do not contribute to the formation of these tubular networks. Reassembly of the Golgi complex after BFA incubation involved fragmentation and reorganization of the tubular networks as well as fusion with vesicles budded from the ER. We conclude that although in the presence of BFA the bulk of Golgi membranes are induced to fuse with the ER, as indicated by the detection of Golgi markers in this organelle, a fraction of these membranes remain in the cytoplasm organized as Golgi remnants.

Retinol stimulates Golgi apparatus activity in cultured bovine mammary gland epithelial cells

Biochemical and electron microscopic studies have indicated that the Golgi apparatus responds to retinol. The purpose of this investigation was to visualize and record with living cells the rapidity of the response to retinol. A rapid response of the Golgi apparatus to retinol (1.75-17.5 mumol/L) added to the culture medium was observed using video-enhanced light microscopy with bovine mammary epithelial cells. The response was manifested within 1 min as a marked movement of membranes within the Golgi apparatus zone. In subsequent electron microscope preparations of the cells, only minor changes were observed and were restricted to increased numbers of normal-appearing membranes and vesicles associated with the trans Golgi apparatus face of the retinol-treated cells.

Cytochemical and stereological analysis of rat cortical astrocytes during development in primary culture. Effect of prenatal exposure to ethanol

This study has investigated the effect of prenatal alcohol exposure on the qualitative and quantitative ultrastructure of proliferating and differentiated astrocytes in primary cultures as well as on the cytochemical activity of several subcellular phosphatase markers, including acid phosphatase, uridine diphosphatase, thiamine pyrophosphatase, 5'-nucleotidase and glucose-6-phosphatase. The astrocytes were obtained from 21-day-fetuses of both control and alcohol-fed rats. Our results show that several cell components, such as mitochondria, rough endoplasmic reticulum and lysosomes, exhibit qualitative and/or quantitative ultrastructural changes during the process of astrocyte maturation. In some cases these morphological changes are accompanied by variations in the cytochemical activity of enzymes located in these and other cell components, suggesting that these enzymes, and therefore the functional state of these organelles, are modulated during astrocyte development. When prenatally exposed to ethanol, both proliferating and differentiated astrocytes showed striking ultrastructural alterations compared with controls, including an increment of lysosomes as well as a decrease in the values of stereological parameters relative to mitochondria, rough endoplasmic reticulum and Golgi apparatus. Cytochemical analysis of these cells indicates that prenatal exposure to ethanol decreased the activities of all the enzymes tested, except for acid phosphatase, which was increased in both groups of treated astrocytes. These results suggest that prenatal exposure to ethanol could affect astrocytes during development in two different but probably complementary ways: a) by causing a delay in astrocyte maturation and, b) by inducing a direct toxic effect on these cells.

Structural and cytochemical study of the rat exocrine pancreas treated with dl-ethionine. I. Multilayered bodies and lesioned areas

The fine structural changes and the reactivity for acid phosphatase (AcPase) and thiamine pyrophosphatase (TPPase) were studied in thin sections from rat pancreatic acinar cells exposed to dl-ethionine for 2-10 days. The cells from ad libitum and pair-fed controls exhibit occasionally 0.2-0.6 microns circular profiles showing reaction for AcPase and considered as presumptive lysosomes. At days 2 and 4 of dl-ethionine treatment the acinar cells exhibit presumptive lysosomes, autophagosomes and membrane-bounded cytoplasmic areas devoid of electron density and AcPase activity, containing scattered membranous elements. These regions were named lesioned areas. On 6th, 8th and 10th days a membrane bound anomalous cytoplasmic structure that represents a dense pile of layered membrane-like material (multilayered bodies, MB) was seen. The MBs consistently show AcPase activity and in rare instances TPPase activity. Freeze fracture studies reveal that the limiting membrane of the MBs has intramembranous particles whereas the multilayered membranous contents are devoid of such particles. The structure and disposition of the lamellae of the MBs seen in the replicas are similar to those of artificially prepared phospholipidic membranes.

Cytochemical localization of enzyme markers in Tritrichomonas foetus

Cytochemical techniques associated with transmission electron microscopy were used for the localization in Tritrichomonas foetus of enzymes used as markers of different cell structures. Reaction product indicating the presence of Mg(2+)-adenosine triphosphatase (Mg(2+)-ATPase) and 5'-nucleotidase was observed in the plasma membrane. Glucose-6-phosphatase was seen in association with the endoplasmic reticulum, revealing its organization as parallel cisternae. Thiamino-pyrophosphatase was located in the cis-most region of the Golgi complex. Acid phosphatase was found within lysosomes as well as in several cisternae of the Golgi complex, in contrast to previous observations in mammalian cells. These observations provide support for the use of enzyme markers in future studies on cell fractionation of T. foetus.

Lysosomal depletion in macrophages from spleen and foot lesions of Leishmania-infected hamster

Analysis of lysosomes through acid phosphatase cytochemistry at the electron microscopy level has been performed in spleen and foot lesions from Leishmania-infected hamsters. The results showed that there is lysosomal depletion in macrophages from Leishmania donovani chagasi-infected hamster spleen and similar findings were obtained from foot lesions of Leishmania mexicana amazonensis-infected hamsters. The distribution of acid phosphatase and thiamine pyrophosphatase was also examined in the Golgi apparatus. It was possible to demonstrate that the activity of ACP is absent in infected macrophages from spleen and foot lesions of Leishmania-infected hamster while the distribution of TPP was very similar in control and infected macrophages from both systems. These results provide evidence that the lysosomal depletion can occur at the ACP synthesis and/or glycosylation level.

Ultrastructural localization of phosphatase activity in the guinea pig pineal gland by the cerium technique

Thiamine pyrophosphatase (TPPase), nucleoside diphosphatase (NDPase), and glucose-6-phosphatase (G-6-Pase) were localized by the cerium technique in guinea pig pinealocytes and compared with the corresponding lead technique. NDPase and TPPase were also compared at different pH values using the cerium technique. Vibratome sections of perfusion-fixed tissue were incubated with cerium chloride or lead nitrate. Substrates used were thiamine pyrophosphate (for TPPase), sodium inosine diphosphate (NDPase), and disodium glucose-6-phosphate (G-6-Pase). The 1-2 trans saccules of the Golgi apparatus showed TPPase and NDPase activity but none for G-6-Pase. The endoplasmic reticulum (ER) cisternae and perinuclear space had NDPase and G-6-Pase activity but not TPPase. The abluminal plasmalemma of endothelial cells and the plasmalemma of Schwann cells demonstrated TPPase and NDPase activity but the luminal plasmalemma of the endothelial cells and the plasmalemma of pinealocyte processes showed only NDPase activity. TPPase was active at all pH values tested, but NDPase was most active at pH values of 6.5 and 7.0. Lead phosphate precipitate was frequently seen in nuclei, perinuclear space, ER cisternae, and "synaptic" vesicles when lead was used as the capturing agent. These sites were usually not labeled when cerium was used.

Molecular trapping of a fluorescent ceramide analogue at the Golgi apparatus of fixed cells: interaction with endogenous lipids provides a trans-Golgi marker for both light and electron microscopy

We have previously shown that a fluorescent derivative of ceramide, N-(epsilon-7-nitrobenz-2-oxa-1,3-diazol-4-yl-aminocaproyl)-D-eryth ro-sphingosin e (C6-NBD-Cer), vitally stains the Golgi apparatus of cells (Lipsky, N. G., and R. E. Pagano. 1985. Science (Wash. DC). 228:745-747). In the present paper we demonstrate that C6-NBD-Cer also accumulates at the Golgi apparatus of fixed cells and we explore the mechanism by which this occurs. When human skin fibroblasts were fixed with glutaraldehyde and then incubated with C6-NBD-Cer at 2 degrees C, the fluorescent lipid spontaneously transferred into the cells, labeling the Golgi apparatus as well as other intracellular membranes. Subsequent incubations with defatted BSA at 24 degrees C removed excess C6-NBD-Cer from the cells such that fluorescence was then detected only at the Golgi apparatus. Similar results were obtained using other cell types. A method for visualizing the fluorescent lipid at the electron microscopic level, based on the photoconversion of a fluorescent marker to a diaminobenzidine product (Sandell, J. H., and R. H. Masland, 1988. J. Histochem. Cytochem. 36:555-559), is described and evidence is presented that C6-NBD-Cer was localized to the trans cisternae of the Golgi apparatus. While accumulation occurred in cells fixed in various ways, it was inhibited when fixation protocols that extract or modify cellular lipids were used. In addition, Filipin, which forms complexes with cellular cholesterol, labeled the Golgi apparatus of fixed cells and inhibited accumulation of C6-NBD-Cer at the Golgi apparatus. These results are discussed in terms of a simple model based on the physical properties of C6-NBD-Cer and its interactions with endogenous lipids of the Golgi apparatus. Possible implications of these findings for metabolism and transport of (fluorescent) sphingolipids in vivo are also presented.

Improved high-performance liquid chromatographic determination of thiamine and its phosphate esters in animal tissues

An improved method for the determination of thiamine and its phosphate esters in animal tissues using reversed-phase high-performance liquid chromatography with precolumn derivatization is described. Thiamine and its phosphate esters were converted into fluorophores by alkaline cyanogen bromide, and the derivatives were applied to an ODS packed column. Then the effluent obtained by an acidic mobile phase was mixed with an alkaline methanol solution to increase the fluorescence intensity of the derivatives which was determined spectrofluorometrically. A complete, rapid and quantitative separation of thiamin and its phosphate esters was achieved and the use of the acidic buffer as a mobile phase improved the column stability. The fluorophores of thiochrome ester peaks on the chromatogram were sensitive to pretreatment with thiamine triphosphatase or acid phosphatase. The applicability of the method to the determination of the form of thiamin in various tissues of rat is demonstrated.

Thiamine pyrophosphatase (nucleoside diphosphatase) in the Golgi apparatus is distinct from microsomal nucleoside diphosphatase

The properties of thiamine pyrophosphatase in the Golgi apparatus of rat liver were studied. Thiamine pyrophosphatase in an extract of the Golgi apparatus was separated into 6 bands of between pH 5.4 and 6.3 by isoelectric focusing on polyacrylamide gel. On the gels all these subforms catalyzed the hydrolyses of GDP, IDP, UDP, and CDP as well as that of thiamine pyrophosphate. The characteristics resembled those of Type B nucleoside diphosphatase of rat brain, though the enzyme did not have 3 subforms of Type B nucleoside diphosphatase in the higher pH region on isoelectric focusing. Thiamine pyrophosphatase of the Golgi apparatus was separated from microsomal nucleoside diphosphatase by DEAE-cellulose column chromatography. The properties of the enzyme were quite similar to those of Type B nucleoside diphosphatase with respect to its substrate specificity, optimum pH for activity, and inhibition by ATP. These findings suggest that thiamine pyrophosphatase in the Golgi apparatus is different from microsomal nucleoside diphosphatase and that it might be basically the same enzyme as Type B nucleoside diphosphatase except for different extents of modification.

Ultrastructural phosphatase histochemistry of submandibular and parotid salivary glands of man

Thiamine pyrophosphatase was demonstrated in the Golgi complex and acid phosphatase in the GERL of acinar cells of submandibular and parotid glands and were previously demonstrated in cells of intercalary ducts. Thiamine pyrophosphatase was also demonstrated in the Golgi complex of cells of striated and excretory ducts and myoepithelial cells. Acid phosphatase was also demonstrated in lysosomes. Alkaline phosphatase was rarely demonstrated light microscopically at luminal surfaces of striated and excretory ducts and electron microscopically in luminal vesicles in cells of striated ducts. The demonstration of the phosphatases in Golgi complexes and GERLs indicates that investigations on these structures in experimental animals are relevant to human salivary glands and supports the opinion that ductal cells as well as acinar cells secrete organic material. The presence of alkaline phosphatase at luminal surfaces of striated and excretory ducts suggests that resorption as well as secretion may occur in them.

Hydrolase cytochemistry during follicular atresia in mammals

Activity changes of thiamine pyrophosphatase (TPPase), acid phosphatase (aP), non-specific esterase (nE), acid beta-galactosidase (a beta Gal), beta-glucuronidase (beta-Gluc), and beta-D-N-acetylglucosaminidase (NAG) in follicles during atresia were investigated in the ovaries of mice, rats, Mongolian gerbils, hamsters, guines pigs, rabbits, cats, and pigs. Changes of hydrolase activity were highly enzyme dependent, species-specific and mostly confined to the granulosa. Decrease of TPPase activity and increase of lysosomal enzyme activities during atresia appeared to be true for all mammals. The start of activity changes in the time course of atresia depended on the occurrence of the enzyme in the growing granulosa. Continuous increase of lysosomal enzyme activity appeared in follicles where these enzymes could also be found in the growing granulosa. In contrast, when lysosomal enzyme activity was low or could not be detected in the growing granulosa, increased enzyme activity could only be observed at a time when degenerative processes have already progressed considerably. This distribution pattern suggests that hydrolytic enzymes in the granulosa cells as well as hydrolases of invading macrophages participate in this degenerative process. In some mammals, enzyme activity changes appeared in the cumulus oophorus for the first time in advanced stages of degeneration. In some mammals enzyme activity changes were dependent on the developmental stage of the follicle. This stage dependency argues for an interrelationship between activation of lysosomal enzymes and androgen metabolism.

Cytochemical studies on induced autophagocytosis in mouse exocrine pancreas

1. The origin of the limiting membranes of autophagic vacuoles (AVs) in mouse pancreatic acinar cells was studied in vinblastine-induced autophagocytosis. 2. The marker enzymes used were adenosine triphosphatase, lipase, inosine diphosphatase and thiamine pyrophosphatase. The following impregnation techniques were used: unbuffered osmium tetroxide impregnation, imidazole-buffered osmium tetroxide impregnation and uranyl-lead-copper impregnation. 3. Only a weak lipase activity was observed between the limiting membranes of a few AVs. The AV membranes were stained heavily with all impregnation techniques used. 4. The origin of AV membranes seems to be same in mouse liver and exocrine pancreas in vinblastine-induced autophagocytosis.

Prenatal exposure to alcohol alters the Golgi apparatus of newborn rat hepatocytes: a cytochemical study

The effect of prenatal exposure to ethanol on the Golgi apparatus of newborn rat hepatocytes has been studied cytochemically using several trans-Golgi markers (thiamine pyrophosphatase, uridine diphosphatase, inosine diphosphatase, acid phosphatase, and 5'-nucleotidase) as well as a cis-side marker (osmium impregnation). The amount of cerium phosphate formed in the cytochemical reactions was roughly quantitated by stereologic methods. The Golgi apparatus of about 40% of the hepatocytes appeared disorganized after alcohol treatment, and in the other 60%, the electron density of reaction product deposits for all phosphatases investigated was decreased. 5'-Nucleotidase was completely absent in cisternae of Golgi apparatus of treated cells. In control cells impregnated with osmium tetroxide, reduced osmium compounds were observed in most Golgi cisternae and in nearby vesicles. In contrast, only small vesicles appeared positive in treated hepatocytes. These results suggest that prenatal alcohol exposure alters some Golgi functions. Thus, the decrease in nucleoside diphosphatase and 5'-nucleotidase cytochemical activities after ethanol exposure strongly suggests that this treatment could affect glycosylation in the Golgi apparatus of newborn rat hepatocytes.

Ultracytochemical evidence for the presence of GERL in pinealocytes of the Mongolian gerbil (Meriones unguiculatus)

Ultracytochemical reactions for the demonstration of acid phosphatase, glucose-6-phosphatase and thiamine pyrophosphatase, as well as zinc iodide-osmium tetroxide impregnation, revealed the existence of GERL (Golgi apparatus-Endoplasmic Reticulum-Lysosomes) in pinealocytes of the Mongolian gerbil (Meriones unguiculatus). The spatial arrangement of this structure was studied on thick sections using a goniometric stage. Although it was not possible to determine whether GERL in pinealocytes belongs to the Golgi apparatus or to endoplasmic reticulum, it can be concluded that its presence in studied cells signifies that they are considerably more active synthetically than has been believed to date.

Phosphatase localization in the endomembrane system of the dinoflagellate Crypthecodinium cohnii

The distribution of four enzymes within the endomembrane system of the protist Crypthecodinium cohnii has been determined using cytochemical localizations with lead as a capture agent. Nucleoside diphosphatase (NDPase) activity, using inosine diphosphate (IDP) and thiamine pyrophosphate (TPP) as substrates, was observed in the Golgi apparatus, with a gradient of increasing reaction product noted in some cells from the cis to trans cisternae. Tubules and vesicles associated with the trans cisternae also contained reaction product. The endoplasmic reticulum exhibited a high activity of glucose-6-phosphatase [with glucose-6-phosphate (G-6-P) as substrate]. Traces of reaction product were also observed in the cis-most and trans-most cisternae of the dictyosomes. Activity of acid phosphatase (AcPase) was observed in Golgi cisternae as well as in associated cytoplasmic vesicles. Heaviest deposition was localized in medial and trans dictyosome cisternae. The cytoplasmic system of flattened vesicles subtending the surface membranes in these cells did not exhibit reactivity with any of the substrates used. The distribution of these enzymes in this algal cell appears similar to that observed in animal cells and suggests that these enzymes may represent markers for algal cell endomembrane compartments.

Histoenzymatic, karyometric, and DNA cytophotometric studies on rat neuroglia following administration of BCNU (carmustine)

BCNU is a nitrosourea derivative applied in anti-neoplastic therapy. As a result of conversion under in vivo-conditions, products of alkylating properties are formed which derrange DNA metabolism, and products of carbamylating activity which disturb protein metabolism. Studies on BCNU neurotoxicity were performed on 20 adult rats of Wistar strain which were given the compound intraperitoneally, in doses corresponding to those used for tumour treatment in humans. Material for estimating unfavorable effects of the drug on central nervous system involved brains, the sections of which were subjected to histoenzymatic reactions and stained according to FEULGEN for karyometric studies and DNA cytophotometry. Size and shape estimates for nuclei of the cells and their DNA content were obtained using Morphoquant automatic microscopic image analyzer (VEB Carl Zeiss, Jena) and compared to those of neuroglia of control animals, given no drug. Multiple intraperitoneal injections of BCNU induced distinct histoenzymatic, karyometric, and cytophotometric changes in oligodendroglia and astroglia. In oligodendroglia, lowered NsE and AcP activities and augmented TPPase activity were noted while in astroglia decreased activity of the former 2 enzymes was associated with an augmented ATPase activity. In karyometric studies, significant decrease in the size of astroglia and in DNA extinction was noted. No karyometric or cytophotometric alterations were noted in oligodendroglia nuclei. Results of the presented studies may indicate primary injury to vascular walls and secondary damage to neuroglia.

Enzymhistochemical identification of microglial cells in the rat retina: light and electron microscopic studies

We used the method of thiamine pyrophosphatase (TPPase) enzyme histochemistry and flat-mounted and transverse-sectioned retinas to identify microglial cells. Light microscopically, TPPase activity was demonstrated on the outer surfaces of glial cells located in the inner plexiform layer (IPL) and the ganglion cell layer (GCL) of the entire retinal regions, and also on the outer surfaces of blood vessels. Electron microscopically, TPPase activity was observed on the plasma membranes of the glial cells, the endothelial cells of microvessels and the pericytes. The TPPase-positive glial cells had a dark nucleus with large clumps of chromatin beneath the nuclear envelope. These findings strongly suggest that the glial cells with TPPase activity observed in the IPL and the GCL of the rat retina were microglial cells.

Granule formation in large granular lymphocytes (LGL). Ultrastructural and cytochemical studies on cells from patients with abnormally expanded lgl populations

The peripheral blood mononuclear cells from five patients with abnormally expanded populations of large granular lymphocytes (LGL) of possible malignant origin have been studied by electron microscopy. These cells had fewer granules than normal circulating LGL but displayed a variety of organelles possibly involved in the process of granule formation. This process apparently originated from the fusion of vesicles that had a characteristic cup-shape (and appeared to be derived from the Golgi apparatus) with smaller vesicles, mostly of the coated type. This fusion resulted in the formation of multivesicular bodies (MVB) whose limiting membrane was constituted by that of the cup-shaped vesicle. MVB gradually matured into electron-dense granules. A number of cup-shaped vesicles were found positive for the cytochemical localization of thiamine pyrophosphatase (TPP) activity that is a specific marker of the trans aspect of the Golgi apparatus, a finding which confirmed that they were Golgi-derived. The smaller, mostly coated, vesicles were positive for acid phosphatase (AP) and evidence was obtained indicating that they subserved the function of transporting acid hydrolases from the rough endoplasmic reticulum to the cup-shaped vesicles or to the MVB. The plasma membrane did not appear to contribute to MVB or granule formation since endocytic vacuoles induced by reacting the cell surface with the appropriate monoclonal antibodies (followed by peroxidase labelled anti-immunoglobulin) were never seen while fusing with granules or MVB. Rather, these vesicles formed secondary lysosomes after having encountered smooth or, more rarely, coated vesicles. Granulogenesis in LGL, therefore, resembles the process of granule formation observed in secretory cells. The active process of granulogenesis detected in the patient cells and a number of other findings indicate that they were LGL at early stages of maturation. The surface phenotype consistently found in these cells (OKT3+, Leu 1+, OKT8+, Leu 2a+, OKT11+, Leu 5+ and OKM1) is different from that of the majority of the normal LGL and may correspond to that of immature LGL.

Subcellular location of stimulus-affected endogenous phosphoproteins in the rat parotid gland

Rat parotid minces were labeled with [32P]Pi, stimulated with isoproterenol, homogenized in sucrose, and fractionated on continuous sucrose density gradients. We analyzed the resulting fractions by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiograms were made from the gels. Comparison of fractions from control and isoproterenol-stimulated minces revealed seven phosphoproteins that were affected by isoproterenol. The subcellular location of these proteins was determined by comparing their distribution in the sucrose gradients with that of a number of enzymes that are characteristic of specific organelles. Isoproterenol decreased the phosphorylation of two cytoplasmic proteins (Mr 16,000 and 18,000) and increased the phosphorylation of a third (Mr 14,000). The phosphorylation of two endoplasmic reticulum proteins was increased by isoproterenol (Mr 20,500 and 22,500), as was an Mr 31,000 protein which was probably the S6 ribosomal protein. The phosphorylation of a secretory granule protein (Mr 24,000) was decreased by isoproterenol. We then developed a purification scheme for parotid secretory granules. By using this method, we demonstrated that the phosphorylation of the Mr 24,000 was also decreased by carbamylcholine. Granules purified by this method also contained a small number of other phosphoproteins whose phosphorylation was increased only by isoproterenol. Secretory granule-associated stimulus-affected phosphoproteins were found in the particulate fraction when the granules were hypotonically lysed, and were not extracted from the particulate fraction by washing with 0.6 M KCl.

The Golgi apparatus and lysosomes of rat pancreatic acinar cells following refeeding

The short term effects of refeeding on the Golgi apparatus and lysosomes of the rat exocrine pancreas were evaluated by ultrastructural, morphometric and cytochemical methods. Ten minutes after refeeding, there was a significant enlargement of Golgi cisternae and a significant increase, compared with the controls, in the number of condensing vacuoles and lysosomes. These modifications were accompanied by the appearance of acid phosphatase activity in stacked Golgi cisternae (as well as GERL) of some cells. One hour after refeeding, there were about the same numbers of condensing vacuoles and lysosomes as in the controls; Golgi cisternae were still significantly enlarged, compared with the controls, but they were no longer reactive for acid phosphatase. In both fasting and refed animals, acid phosphatase activity was demonstrable in tubular lysosomes. The data are interpreted in terms both of membrane disposal and recycling, leading to enhanced formation of zymogen granules, during physiologically stimulated secretion.

Cytochemical localization of beta-NADPase in rat hepatocytes and Kupffer cells. Comparison with thiamine pyrophosphatase (TPPase)

The intracellular localization of beta-NADPase in rat hepatocytes and Kupffer cells has been studied and compared with the pattern of TPPase in these cells. The reaction product for beta-NADPase is present in some but not all hepatocytes in two cisternae on the trans aspect of the Golgi apparatus. It is absent from the trans-most lamella and the GERL of hepatocytes. TPPase, on the other hand, is limited to the first Golgi cisterna on the trans aspect with sprinkles of reaction product in the second lamella. Considering that TPPase is a marker of the trans Golgi lamella and hepatocyte Golgi stacks contain usually 2-4 lamellae, our observations suggest that beta-NADPase is localized in the trans as well as in the intermediate Golgi lamellae of liver parenchymal cells. In Kupffer cells, the reaction product for both beta-NADPase and TPPase was found in some but not in all cells. The enzyme beta-NADPase was localized in the rigid lamella and the tubulovacuolar system of GERL. This pattern differed significantly from that for TPPase, which was found in 2-3 cisternae at the trans aspect of the Golgi complex in Kupffer cells. These observations demonstrate the difference in the localization of beta-NADPase in hepatocytes and Kupffer cells. Such differences should be taken into consideration in studies of Golgi fractions, when phosphatase reactions are used as specific markers of Golgi components.

Cytochemical and ultrastructural changes in aflatoxin-induced injury to rat liver cells

Young male Sprague-Dawley rats were injected intraperitoneally with a single dose of aflatoxin B1 (AFB1, 3 mg/kg). At 3, 6, 12, and 24 hours and 1, 2, and 5 weeks, the rats were killed and liver samples were taken for examination of sequential ultrastructural changes and localization of acid phosphatase (AcPase), thiamine pyrophosphatase (TPPase) and glucose-6-phosphatase (G6Pase) activity. At 3-6 hrs of AFB1 treatment, the nucleoli became compacted and the network forms of nucleolonema disappeared. Parallel arrays of rough ER encountered in normal liver cells became deranged. Smooth ER increased to form groups of SER anastomosis or vesicles near the golgi area. At 12-24 hours, disruptions of nucleoli, ER systems, and polysomes became more evident. Parallel arrays of ER membranes, forming whorls in the cytoplasm as well as in the cytoplasmic patches (CP), were G6Pase-positive, although the CP were AcPase-negative. The TPPase reaction in bile canaliculi was frequently diminished, but was present in some measure in the Golgi saccules. By 1-2 weeks, most of the injured cells had recovered gradually. The CP disappeared and parallel arrays of RER were observed again in most parenchymal cells. At 5 weeks, the appearance of the nucleoli was normal, as was that of the other organelles. We concluded that the hepatic parenchymal cells had serious lesions at 12 and 24 hours of AFB1 treatment and then recovered nonsynchronously. The response, resistance, and ability to recover from the toxicity of AFB1 varied among the parenchymal cells. The three marker enzymes persisted throughout all regimens of AFB1 treatment.

Effect of monensin on the Golgi apparatus of absorptive cells in the small intestine of the rat. Morphological and cytochemical studies

The effect of short-time treatment with the ionophore monensin, administered intraluminally at concentrations of 5 and 10 microM, was studied on the Golgi apparatus of absorptive cells in the small intestine of the rat. At 2-3 min after treatment most of the Golgi stacks exhibited dilated cisternae. At 4-5 min stacked cisternae were absent; they were replaced by groups of smooth-surfaced vacuoles. Dilatation and vacuolization occurred in the entire stacks without preferential effect on any particular Golgi subcompartment. Monensin did not influence the cytochemical Golgi reaction of thiamine pyrophosphatase and acid phosphatase. The characteristic staining pattern of these two enzymes in all Golgi cisternae of absorptive cells in the proximal small intestine, and the reactivity restricted to trans cisternae in distal segments of the small intestine, were unchanged after treatment with monensin. In the distal small intestine, the cytochemical pattern allowed the monensin-induced vacuoles to be attributed to the former cis- or trans-Golgi face. Further, the cytochemical results demonstrate that vacuolization is not restricted to the stacked cisternae, but includes the trans-most cisterna. The latter, usually located at some distance from the Golgi stacks, has been defined as belonging to the GERL system in several types of cells. The clear response to monensin, an agent that selectively affects the Golgi apparatus, indicates common properties between trans-most and stacked Golgi cisternae.

Topography of cerebroside sulfotransferase in Golgi-enriched vesicles from rat brain

Cerebroside sulfotransferase (CST) catalyzes the final step in the synthesis of sulfatide (sulfogalactocerebroside) by transferring the sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to galactocerebroside. Orientation of CST was studied in vesicles enriched in this enzyme obtained from 21-d-old rat brain. Several lines of evidence indicate that CST is located on the luminal side of these vesicles. (a) Sulfation of endogenous galactocerebroside occurred in vesicles only in the presence of a detergent to render the membranes permeable to exogenous PAPS. (b) There is a pool of latent enzyme within the vesicle, which is released by Triton X-100. (c) CST is not destroyed by trypsin unless the vesicle membranes are first made permeable by Triton X-100. (d) Glycolipid substrate, when covalently attached to agarose beads, was not sulfated unless the enzyme was solubilized. These results are similar to those obtained with thiamine pyrophosphatase, which is known to be located within the lumen of the vesicles. This study establishes that an enzyme synthesizing a complex glycolipid is localized within Golgi-enriched vesicles. Since the product of the CST reaction must also be localized to the luminal side of the vesicles, it is most likely that sulfatide is located at the intraperiod line (outer layer) of myelin. The orientation of CST within the vesicle provides a mechanism for the asymmetrical assembly of glycolipids in bilayers.

Enzyme modulation of the Golgi apparatus and GERL: a cytochemical study of parotid acinar cells

The distribution of thiamine pyrophosphatase (TPPase) and acid phosphatase (AcPase) has been examined in resting parotid acinar cells as well as during decreased and increased secretory granule production. In resting acinar cells, TPPase activity was restricted to the trans Golgi saccules and AcPase activity was localized in GERL and immature secretory granules. Although secretory granule production is diminished during ethionine intoxication, no significant alteration in the distribution of either TPPase or AcPase was noted. However, marked changes in enzyme localization, especially of TPPase, occurred during accelerated secretory granule production. The alterations were essentially the same for all of the conditions studied (recovery from ethionine treatment, recovery from a protein depletion diet, secretory stimulation with isoproterenol, and postnatal maturation of the parotid gland). During maximal secretory granule production, TPPase activity was localized not only in the trans Golgi saccules, but also in GERL-like cisternae and immature secretory granules. The immature secretory granules were often in continuity with the GERL-like cisternae. At the same time that the TPPase activity was increased, the AcPase activity was frequently diminished. These modulations in enzyme activity provide evidence that GERL is derived from the trans Golgi saccule.

A cytochemical study of acid phosphatase, thiamine pyrophosphatase and horseradish peroxidase in the Golgi-GERL complex of hepatoma ascites cells

Data from studies of ascitic cells of Chang hepatoma have shown that acid phosphatase (ACPase) can be localized simultaneously within the trans portion of the Golgi apparatus and in tubules of the Golgi-endoplasmic reticulum-lysosome (GERL) system. Reaction products of thiamine pyrophosphatase (TPPase) were also present consistently within trans elements of the Golgi apparatus and within GERL tubules. These new findings indicate that a close physiological association may exist between the Golgi apparatus and GERL, a concept that is consistent with previous observations of fibroblasts. When horseradish peroxidase (PO) is injected intraperitoneally into ascites-bearing rats and the ascitic cells withdrawn at different time intervals, PO could be localized within vesicles and tubules in the GERL region but could not be detected within the Golgi apparatus. Bulk-phase endocytosis requires a long time and a high concentration of PO to occur. The presence of PO within GERL indicates that this organelle may play a role in transporting or processing of certain exogenous proteins.

Stage-dependent enzymatic activities in spermatogenesis of mice with the standard karyotype and of chromosomal variants with impaired fertility

The enzymatic activities of thiamine pyrophosphatase (TPPase), acid phosphatases (ACPases), alkaline phosphatases (APases) and steroid-3 beta-ol dehydrogenase (beta-HSDH) in different germ cells and somatic cells in the testis of three cytogenetically determined states of fertility (i.e. normal, impaired fertility and sterility) were studied histochemically in the mouse. The TPPase, ACPases and APases activities showed a characteristic stage dependent pattern when the activities were related to the typical twelve stages of the seminiferous epithelium in the mouse, according to Oakberg (1956). Comparing the enzymatic patterns of the activities in the normal spermatogenic process versus the impaired and sterile conditions, the following conclusions can be drawn: even in impaired and sterile conditions the enzymatic activity patterns retain their characteristic stage dependence; the pattern of beta-HSDH and ACPases is not altered in the impaired and sterile conditions; TPPase and APases patterns are modified in impaired and sterile mice. It is concluded that the kinetics of the enzyme activities can serve as a useful marker for characterizing pathological spermatogenic processes.

Histochemical studies on the distribution of thiamine pyrophosphatase and enzymes related to carbohydrate metabolism in the intercalated neurons of the rat supraoptic nucleus

Histochemical studies have been conducted by applying hexokinase (HK), aldolase (AD), glyceraldehyde-3-phosphate dehydrogenase (G3), succinate dehydrogenase (SDH), glucose-6-phosphate dehydrogenase (G6PD), and thiamine pyrophosphatase (TPPase) methods, as well as Nissl staining and Gomori's chrome-alum-hematoxylin-phloxine (CHP) methods to intercalated neurons of the supraoptic nucleus (SO) on Wistar strain rats. Intercalated neurons reacted weakly to the AD, G3, G6PD, and SDH tests, indicating that they belong to the category of ordinary neurons with low carbohydrate metabolism. Many fibrous astrocytes showing strong HK reactions surround neurosecretory neurons. However, they do not surround intercalated neurons with mild HK activity. These results indicate that the latter receive a poor supply of energy from glucose in the circulating blood in contrast to the former. Intercalated neurons are very rich in Nissl substance but lack CHP-positive material. They may have a high potential for synthesizing protein. The principal morphological features of the TPPase-positive Golgi material are peculiar and heterogeneous shape and poor development. These findings together with mild G6PD activity suggest that intercalated neurons are very likely to have poor synthesizing activity.

Localization of vasoactive intestinal polypeptide- and avian pancreatic polypeptide-like immunoreactivity in the Golgi apparatus of peripheral neurons

Using the indirect immunofluorescence technique of Coons and collaborators, vasoactive intestinal polypeptide (VIP)-like immunoreactivity (VIP-LI) and avian pancreatic polypeptide (APP)-like immunoreactivity (APP-LI) was observed in certain neurons of the peripheral nervous system of the cat. In the cell bodies in the cat sympathetic ganglia a strong to very strong VIP-LI or APP-LI was observed with a distribution resembling that of the Golgi apparatus. In addition, a weaker immunoreactivity was seen diffusely in the cytoplasm. After photography, the sections processed for immunohistochemistry were stained with the thiamine pyrophosphatase technique of Novikoff and Goldfischer. The latter technique is assumed to be a specific marker for the Golgi complex. In all cases it was found that the strong peptide immunoreactivity and the thiamine pyrophosphatase activity had an identical distribution. Thus, one pool of these peptides appears to be localized to the Golgi apparatus. Yet another pool is localized to other components, such as vesicles.

Studies on vinblastine-induced autophagocytosis in mouse liver. IV. Origin of membranes

The origin of the limiting membranes of autophagic vacuoles (AV) in mouse hepatocytes was studied by cytochemical techniques. Autophagocytosis was induced by an intraperitoneal injection of vinblastine (50 mg/kg). The marker enzymes used were adenosine triphosphatase for the plasma membrane, glucose-6-phosphatase for the endoplasmic reticulum and thiamine pyrophosphatase for the Golgi apparatus and the endoplasmic reticulum. All the three enzymes showed a characteristic localization in both control and vinblastine-treated hepatocytes. The space between the limiting membranes of a few apparently newly formed AV's showed weak glucose-6-phosphatase activity. Neither adenosine triphosphatase nor thiamine pyrophosphatase activities were observed on or between the AV membranes. It was suggested that endoplasmic reticulum membranes may be used as a source of AV membranes in hepatocytes. The lack of glucose-6-phosphatase activity in the limiting membranes even of most of the newly formed AV's suggests a transformation process of the membranes destined to form AV, during which the enzyme activity characteristic for endoplasmic reticulum may disappear from them.

Histoenzymatic and morphometric changes occurring in nerve cells of gyrus cinguli following treatment of young rats with vincristine

The effect of treatment with vincristine on nerve cells of gyrus cinguli was studied. Wistar rats aged 1, 3, 7, 14, 21 and 28 days were given single intraperitoneal injections of vincristine (0.01 mg/kg body weight). All experimental animals were decapitated at the age of 29 days and their brains subjected to histoenzymatic and morphometric examination. The control group consisted of untreated rats aged 29 days. The activity of phosphatases and esterases of the cingulum was evaluated histochemically and the morphometric parameters of pyramidal cells in this region were determined by means of a computer microscope "Morphoquant" (VEB Carl Zeiss JENA). The results of this study have shown that administration of therapeutic doses of vincristine to young rats brings about a drop of the neuronal AChE and NsE activity, contrary, to this, TPPase and acP activities of the pyramidal cells are enhanced by this treatment. Morphometric determinations have revealed elongation of the neuronal perikaryons along with an increase of indices of the cytoplasmatic area and volume of pyramidal cells. The observed alterations are considered to reflect degenerative processes of moderate intensity.

Morphological studies on neuroglia. V. Microglial cells in the cerebral cortex of the rat, with special reference to their possible involvement in synaptic function

Electron-microscopic survey of selectively stained microglial cells in the cerebral cortex of the rat reveals that the processes of this cell type often encircle axo-dendritic synapses. Enzyme-histochemical methods for thiamine pyrophosphatase (TPPase) or nucleoside diphosphatase (NDPase) were used for the selective marking of the microglial cells; TPPase and NDPase activities were observed in the plasma membrane of microglial cells. The synapses encircled by microglial processes displayed presynaptic structures containing round clear vesicles (50 nm in diameter) and a prominent thickening of the postsynaptic membrane. In vitro, the above-mentioned enzymatic activities were completely suppressed by neuroactive agents such as catecholamines and phenothiazine derivatives. Examination using enzyme-histochemical techniques suggests that a single enzyme may be responsible for both microglial cells in the normal central nervous tissue is discussed.

Ultrastructural study of enzymes in reactive astrocytes: clarification of astrocytic activity

Enzymes in reactive of the cerebral cortex were examined at the ultrastructural level in an attempt to resolve some conflicting aspects of astrocytic activity. Correlations between morphological and enzyme changes after injury established that the apparent increase in oxidative enzyme activity was exclusively mitochondrial and not an artefactual reaction product resulting from anoxic cellular damage. Pronounced glucose-6-phosphatase activity within cisternae of an increased amount of the granular endoplasmic reticulum was related to increased glycogen. Further evidence from acid phosphatase activity indicated that astrocytes played a minimal role in phagocytosis.

The localization of thiamine pyrophosphatase activity in Meckel's cartilage cells during endochondral ossification

The cytochemical distribution of thiamine pyrophosphatase (TPPase) activity in Meckel's cartilage cells of the mouse embryo has been studied during the endochondral ossification. All the cartilage cells contain reaction product within the Golgi apparatus. In immature chondrocytes, at the reserve cell zone, TPPase activity is restricted to several inner cisternae of independent Golgi apparatus. In mature cells at the proliferative cell zone, several Golgi complexes form a Golgi network connecting with each other by the TPPase positive tubular stalks. Golgi cisternae, condensing vacuoles and vesicles also contain reaction product. In the hypertrophic chondrocytes located in the calcifying zone, their disorganized Golgi apparatus still retain reaction product. Some chondrocytes, even those located within calcified or opened lacunae, exhibit intact structures and normal cytochemical enzyme distribution. These data indicate the possibility that some chondrocytes may survive and contribute the formation of mandible.