The in vivo effects of tetrahydrocannabinol on the activity of lactate and succinate dehydrogenases in rat preovulatory follicles

Summary The effects of ⁹-tetrahydrocannabinol on the activities of lactate and succinate dehydrogenases in the theca interna and membrana granulosa of rat preovulatory follicles have been analysed microdensitometrically using the same injection regime employed in a previous study on steroidogenic enzymes. A small but statistically significant (18%) decrease in succinate dehydrogenase activity was observed in the theca interna, but none in any region of the membrana granulosa. Lactate dehydrogenase activity was unaffected by THC administration. Thus, a dosage and regimen sufficient to cause significant decreases in the activities of steroidogenic enzymes had little effect on succinate and lactate dehydrogenases in rat preovulatory follicles.     

A quantitative cytochemical study of glucose-6-phosphate dehydrogenase and delta 5-3 beta-hydroxysteroid dehydrogenase activity in the membrana granulosa of the ovulable type of follicle of the rat

During the last four days of follicular development prior to ovulation, the activities of delta 5-3 beta-hydroxysteroid dehydrogenase (3 beta OHD) and glucose-6-phosphate dehydrogenase (G-6-PD) were quantified in cryostat sections of the rat ovary. The product of the enzyme reactions were measured using a scanning and integrating microdensitometer. The enzyme activity was measured in the peripheral region, the antral region and the cumulus of the membrana granulosa (MG) of these follicles on the morning of each of the four days of the estrous cycle. G-6-PD activity was measured in the presence and absence of an intermediate hydrogen acceptor, phenazine methosulphate, to provide a measure of the quantity of Type I and Type II Hydrogen (H) generated: Type I H is considered to be related to hydroxylating reactions such as those of steroids and Type II H to other general biosynthetic activities of cells. In all three regions of the MG of follicles of the ovulable type, 3 beta OHD activity was lowest in estrus and diestrus-1, increased on diestrus-2 and peaked in proestrus. In estrus and diestrus-1, the level of 3 beta OHD activity in the three regions was comparable. However, by diestrus-2, and even more conspicuously in proestrus, enzyme activity was significantly greater in the peripheral region than in the antral region or in the cumulus. During the same period, the level of enzyme activity remained comparable in the last two regions. Throughout the estrous cycle, both Type I and Type II H generation from G-6-PD was greatest in the peripheral region, less in the antral region and least in the cumulus. In the eripheral region, Type I H generation increased progressively after diestrus-1, to reach a maximum in prestrus. In the antral region, Type I H generation increased between diestrus-1 and diestrus-2 and then remained unchanged through proestrus. In the cumulus, Type I H generation remained at levels seen in estrus throughout the remainder of the cycle. Generation of Type II H, in the peripheral region was constant throughout the estrous cycle. In contrast, in the antral region and cumulus, Type II H generation was greater in diestrus-1 and diestrus-2 than on either proestrus or estrus.     

Immunolocalization of 3 beta-hydroxysteroid dehydrogenase in human ovary

Immunohistochemical localization of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) was performed in 55 cases of morphologically normal human ovaries by using a specific polyclonal antibody against purified human placental 3 beta-HSD. In small developing follicles, immunoreactivity was observed only in the theca interna but also became recognizable in the membrana granulosa with development of the follicle. At a late stage of folliculogenesis, the intensity of the 3 beta-HSD activity in the membrana granulosa was nearly equal to that of theca interna in 2 or 3 large follicles examined. One to several layers of theca interna cells just beneath membrana granulosa did not demonstrate any immunoreactivity of 3 beta-HSD or that of cytochrome P-450 17 alpha-hydroxylase. These unstained theca interna cells did not appear to be directly involved in ovarian steroidogenesis and might be designated as 'enzymically inactive theca interna cells.' Marked immunoreactivity was observed in luteinized theca and granulosa cells of the corpus luteum.     

Quantitative and qualitative cytochemical analysis of changes in polysaccharides-proteins in rat ovulable and atretic ovarian follicles during the estrous cycle

Summary The glycosaminoglycan (periodic acid — Schiff, PAS) and hyaluronic acid (alcian blue) content of the membrana granulosa, zona pellucida and antrum of rat ovarian follicles was analyzed qualitatively and quantitatively during the estrous cycle in three types of follicles: ovulable, early atretic and late atretic. The qualitative analysis consisted of the conjunctive localization of PAS-reactive, fluorescent granules within the membrana granulosa. The quantitative analysis consisted of microdensitometric measurements of PAS and alcian blue staining within the zona pellucida and antrum of the ovulable and atretic follicles. For the localization of PAS granules within the granulosa cells, ovaries were removed on the day of proestrus, fixed in 6% paraformaldehyde, embedded in methacrylate and sectioned. Following the examination of the cells for fluorescence, the same section was stained with PAS and lead-hematoxylin. In ovulable follicles there was no fluorescence in the membrana granulosa while PAS granules occurred exclusively within the cells of the cumulus and corona radiata. In late atretic follicles, fluorescent-PAS reactive granules were located in the granulosa cells at the periphery of the follicle. During early atresia no fluorescence and very few PAS granules were observed in the granulosa cells. Since fluorescence is a marker for some lysosomes, these observations suggest that the PAS granules in the ovulable follicles may not be a type of lysosome. The amount of stain in the zona pellucida and antrum of the three follicular types was quantified using a scanning and integrating microdensitometer. On all days of the estrous cycle, PAS intensity was higher in the zona pellucida than in the antrum of the three follicular types. PAS staining in the respective antra was the same on all days of the estrous cycle. Intrafollicular PAS staining in the zonae pellucidae differed during the cycle. With respect to the zonae pellucidae, staining intensity in the three follicles was identical on estrus. On diestrus-1, staining intensity was the same in the ovulable and early atretic follicles and less in the late atretic follicle. By diestrus-2 and on proestrus, PAS intensity was highest in the zona pellucida of the ovulable follicle and less in the zona pellucida of both types of atretic follicle. In contrast to this pattern of staining, alcian blue staining intensity was identical in the zona pellucida of all follicles throughout the cycle. There was no difference in intra-antral alcian blue staining intensity on estrus and diestrus-2. On diestrus-1 and proestrus, staining intensity was greater in the antrum of the late atretic follicle than in the antra of the other follicular types. These studies indicate that glycosaminoglycan content is greater in the zona pellucida of the ovulable follicle of the rat on the last two days preceding ovulation than in the zona pellucida of either the early or late atretic follicles. In contrast, hyaluronic acid content remains constant in the zona pellucida of the three follicular types throughout the estrous cycle. These studies also give the first indication that, in the rat, the localization of PAS granules exclusively in the cumulus oophorus and corona radiata may be used to identify ovulable follicles.This work was supported by a research grant from the National Institute of Child Health and Human Development, HD-12684     

Distribution of delta-5 -3beta-hydroxysteroid dehydrogenase activity in the Graafian follicle of the sheep.

The localization of delta-5 -3beta-hydroxysteroid dehydrogenase (3 beta-HSD) has been examined in ovarian follicles in vivo and in vitro, and related to oestrogen and progesterone production. In vivo, during the oestrous cycle, enzyme activity was restricted to the theca interna of the one or two most advanced follicles in each animal, but was present only between Day 2 and 5 and between Day 13 and ovulation. High levels of oestrogen were found in the ovarian venous blood only when follicles containing 3 beta-HSD were present. When sheep were injected with PMSG, the theca interna in a number ofsmall follicles acquired 3 beta-HSD activity and began to secrete oestrogen within 12 hr of the injection. The enzyme was not detected in the membrana granulosa of any follicles before ovulation but within a few hours of ovulation, 3 beta-HSD activity was present in the granulosa lutein cells. In vitro, large activated follicles exhibited 3 beta-HSD activity in the theca interna and secreted high levels of oestrogen into the culture medium. When LH was added to the medium oestrogen secretion was inhibited; within 48 hr, the follicles were secreting high levels of progesterone, and 3 beta-HSD activity was present in both the membrana granulosa and the theca interna. Dibutyryl cyclic adenosine monophosphate mimicked the effect of LH in suppressing oestrogen secretiion, but did not induce production of progesterone; the distribution of 3 beta-HSD activity infollicles treated with this nucleotide was the same as in those cultured in control medium.     

Histochemical localization of 3 beta-hydroxysteroid dehydrogenase in marmoset ovaries during pro- and diestrus, with special reference to substrate specificity

We applied qualitative cytochemical procedures to investigate and compare the distribution of 3 beta-hydroxysteroid dehydrogenases (HSDH) in pro- and diestrus ovaries of sexually mature marmosets (Callithrix jacchus) using dehydroepiandrosterone or etiocholane-3 beta-ol-17-one as the substrate. During proestrus dehydroepiandrosterone dehydrogenase (3 beta-5 alpha-HSDH) activity was found in the theca of tertiary follicles and in atretic granulosa cells. In granulosa cells at advanced stages of degeneration, HSDH activity was distinctly higher than in thecal cells. The activity of etiocholane-3 beta-ol-17-one dehydrogenase (3 beta-5 beta-HSDH) exhibited a gradient in preovulatory follicles, ranging from high levels in granulosa cells adjacent to the basement membrane to low levels in cells bordering on the antrum and in cumulus oophorus cells. During diestrus 3 beta-5 alpha-HSDH activity was only detected in the corpora lutea; the level of 3 beta-5 beta-HSDH activity was unchanged in the theca of tertiary follicles and was high in the cells of the corpora lutea. HSDH activity was no longer detectable in atretic granulosa cells using either dehydroepiandrosterone or etiocholane-3 beta-ol-17-one as the substrate. Comparison of the distribution of HSDH during proestrus and diestrus revealed that steroidogenesis in marmoset ovaries occurs in follicular elements during diestrus and almost exclusively in the corpora lutea during diestrus. From this phase-dependent localization, it is possible to determine the stage of the estrous cycle. Furthermore, our findings indicate that the localization of HSDH is dependent on the conformational structure of the substrate used.     

Inhibition of some respiration and dehydrogenase enzyme systems in Escherichia coli NCTC 5933 by phenoxyethanol.

Low concentrations (less than 0.2% w/v) of phenoxyethanol stimulated both the rate of respiration and total oxygen uptakes of Escherichia coli NCTC 5933 suspensions with glucose and other substrates, whilst higher concentrations (0.2--0.6% w/v) although still below those showing significant bactericidal activity, produced progressive levels of inhibition. The degree of respiratory inhibition varied with different substrates in the order malate less than succinate less than pyruvate less than or equal to glucose less than lactate, and suggested appreciable inhibition at a point after malate in the tricarboxylic acid cycle. This suggestion was supported by the use of tetrazolium salts as alternative electron acceptors, and by cytochrome difference spectra, which together implicated malate dehydrogenase as the most likely site of action. Isolated dehydrogenase enzymes of the tricarboxylic acid cycle in cell-free preparations were unaffected by high concentrations of phenoxyethanol (0.8% w/v) with the exception of malate dehydrogenase which was inhibited in extracts to extents similar to those of malate oxidation by intact bacteria. Lineweaver-Burke plots for malate dehydrogenase activity in the presence of phenoxyethanol suggested a competitive inhibition of the oxaloacetic acid-limited reaction and a non-competitive inhibition of the NADH-limited reaction. Accordingly, Ki values were found to be low when the rate of reaction was limited by oxaloacetic acid concentration yet relatively high when NADH was rate limiting.     

3 Alpha-hydroxysteroid dehydrogenase and 3 beta-hydroxysteroid dehydrogenase in the ovary of young Mongolian gerbils

The ovaries of sexually mature, pregnant mare serum gonadotropin (PMSG) stimulated, 12 week old Mongolian gerbils were investigated morphologically and enzyme histochemically for the appearance of the 3 alpha-hydroxy-steroid and the 3 beta-hydroxysteroid dehydrogenase during the estrous cycle. Up to ovulation, on day 3 of the estrous cycle, the number of vesicular follicles increases continuously. Primarily atretic follicles can be seen on day 4. On day 5 corpora lutea appear, but they degenerate already by day 6. During the entire estrous cycle, 3 alpha-hydroxysteroid dehydrogenase and 3 beta-hydroxysteroid dehydrogenase activity can be found in the theca of tertiary follicles and in the interstitial cells, whereas the theca of secondary follicles and the granulosa of healthy follicles do not exhibit any enzyme activity. The activity decreases from day 1 till day 6. The granulosa of atretic follicles and the cells of corpora lutea show only weak activity. It may be significant that the intensity of enzyme activity in the ovary and the estrogen level in the plasma are differently correlated to the estrous cycle.     

Cytophotometric analysis of reaction rates of succinate and lactate dehydrogenase activity in rat liver, heart muscle and tracheal epithelium

Reaction rates of succinate and lactate dehydrogenase activity in cryostat sections of rat liver, tracheal epithelium and heart muscle were monitored by continuous measurement of formazan formation by cytophotometry at room temperature. Incubation media contained polyvinyl alcohol as tissue protectant and Tetranitro BT as final electron acceptor. Control media lacked either substrate or substrate and coenzyme. Controls were also performed by adding malonate (a competitive inhibitor of succinate dehydrogenase), pyruvate (a non-competitive inhibitor of lactate dehydrogenase), oxalate (a competitive inhibitor of lactate dehydrogenase) or N-ethylmaleimide (a blocker of SH groups). A specific malonate-sensitive linear test minus control response for succinate dehydrogenase activity was obtained in liver (1.6 mumol H2cm-3 min-1) and tracheal epithelium (0.8 mumol H2cm-3 min-1) but not in heart muscle. All variations in the incubation conditions tested did not result in a linear test minus control response in the latter tissue. Because the reaction was sensitive to malonate, it was concluded that the initial reaction rate was the specific rate of succinate dehydrogenase activity in heart muscle (9.1 mumol H2 cm-3 min-1). Test minus control reactions for lactate dehydrogenase activity were distinctly non-linear for all tissues tested. This appeared to be due to product inhibition by pyruvate generated during the reaction and therefore it was concluded that the appropriate control reaction was the test reaction in the presence of 20 mM pyruvate. The initial rate of the test minus this control was the true rate of lactate dehydrogenase activity. The lactate dehydrogenase activity thus found in liver parenchyma was 5.0 mumol of H2 generated per cm3 liver tissue per min.     

Oscillations in the activities of respiratory enzymes in synchronized Bacillus subtilis

Abstract The activities of NADH, succinate and lactate dehydrogenases have been measured during the cell cycle of Bacillus subtilis . All three enzymes showed an oscillatory pattern of activity expressed as two maxima and two minima per division cycle. For both succinate and lactate dehydrogenases the maxima occurred at approximately 0.2 and 0.6 of a cycle. The maxima of NADH dehydrogenase activity were out of phase at 0.4 and 0.9 of a cycle and occurred at the same time as the rises in respiratory activity previously reported for this bacterium.     

Enzyme histochemistry of the sheep uterus during the oestrous cycle

Enzyme histochemical techniques were applied to frozen sheep uteri from different stages of the oestrous cycle. The localization and activities of succinate, lactate, glucose-6-phosphate, and isocitrate (NADP+) dehydrogenases and acid and alkaline phosphatases were studied in the luminal and glandular epithelia, caruncle and myometrium. Enzyme activity in the sections was scored on a scale of 0--5. In general the enzyme activity in the uterine caruncles and epithelia was higher than in the myometrium. The myometrium did not show any alkaline phosphatase activity and isocitrate dehydrogenase (NADP+) activity was negligible. The low activities of acid phosphatase and lactate dehydrogenase and the moderate levels of glucose-6-phosphate and succinate dehydrogenases in the myometrium were constant. The caruncular tissue showed high levels of phosphatases and glucose-6-phosphate dehydrogenase, moderate levels of lactate and succinate dehydrogenases, and low levels of isocitrate dehydrogenase (NADP+) throughout the oestrous cycle. Much lower phosphatase and isocitrate dehydrogenase (NADP+) levels were found in the epithelium of deep glands compared with superficial glands. The high activity of acid and alkaline phosphatases in the luminal epithelium and the superficial glands was constant from mid-cycle to ovulation, but a significant decrease was observed immediately after ovulation. The level of dehydrogenases in epithelia was generally high and did not change during the oestrous cycle.     

Delta 5-3 beta-hydroxysteroid dehydrogenase, succinate dehydrogenase and glucose-6-phosphate dehydrogenase in the bovine corpus luteum of estrous cycle: a quantitative histochemical study

Genital organs and blood were obtained from dairy cows at a local abattoir. 3 recently ovulated follicles and 20 corpora lutea of estrous cycle (CLC) were used for the quantitative enzyme histochemical demonstration of delta 5-3 beta-hydroxysteroid dehydrogenase (3 beta-OHSDH), succinate dehydrogenase (SDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) activity, employing a computerized microscope photometer. Progesterone was determined in blood serum by radioimmunoassay. Luteal tissue was grouped into several stages of development according to micromorphological criteria. Activities per volume unit of 3 beta-OHSDH and SDH in large luteal cells (LLC), as well as in small luteal cells (SLC), and luteal tissue (LT), relative amounts of the 3 beta-OHSDH-positive tissue fraction (PLCC), and progesterone concentrations in blood serum exhibited a significant pattern corresponding to the morphological development of the endocrine gland. G-6-PDH showed an increase in activity per volume unit during tissue development lasting until the beginning of regressive changes, and as significant in LLC and LT. Activities per volume unit of 3 beta-OHSDH (p less than or equal to 0.001) and SDH (p less than or equal to 0.01) were higher in LLC than in SLC, indicating superior steroidogenic capacities, while G-6-PDH activity was distinctly higher in the latter (p less than or equal to 0.001). Almost all parameters tested were correlated positively. 3 beta-OHSDH and SDH exhibited a significantly positive correlation in LLC (p less than or equal to 0.01) and LT (p less than or equal to 0.001) during periods of measureable progesterone secretion. In SLC this correlation was nonsignificant (p greater than 0.05). G-6-PDH showed a relative poor correlation to 3 beta-OHSDH (LLC, p less than or equal to 0.05; LT, p less than or equal to 0.01) and SDH (LT, p less than or equal to 0.05). Enzyme activities in LLC as well as in SLC were generally positively correlated (p less than or equal to 0.001). All enzymes tested exhibited a significantly positive correlation with progesterone concentrations in blood serum. This was significant for SDH only during measurable progesterone secretion, and less marked for G-6-PDH.     

Ultrastructure of the theca interna of ovarian follicles in sheep

Summary The theca interna of non-atretic ovarian follicles from 2.0 mm in diameter up to the stage shortly following ovulation was studied by light and electron microscopy.In follicles <3.0mm in diameter, the theca interna consisted of about 8–12 layers of flattened cells, together with many capillaries and small bundles of collagen. Two main forms of cellular differentiation were seen. These were towards either fibroblast-like cells or presumed steroidogenic cells whose cytoplasm contained large amounts of predominantly smooth tubular endoplasmic reticulum, to which some ribosomes were attached. The majority of cells were of relatively undifferentiated or intermediate structure.In larger follicles up to the early stages of oestrus the theca interna cells became larger and less flattened, and cells rich in tubular endoplasmic reticulum became proportionately more numerous. By 18 h after the onset of oestrus the theca interna was oedematous, and many cells possessed pseudopodia. Many cells also contained numerous lipid droplets, but there were no signs of thecal cell degeneration or death. Shortly after ovulation the basal lamina of the membrana granulosa was incomplete, and it became more difficult to distinguish between theca and granulosa layers. Structural heterogeneity, with two major cell types and cells of intermediate structure, was present at all stages.It was concluded that: (1) the theca interna of 2.0–2.9 mm follicles contained many cells whose structure was compatible with a steroidogenic capacity; (2) changes in the differentiated thecal cells up to the early stages of oestrus were quantitative rather than qualitative, and suggestive of an increased steroidogenic capacity; (3) the accumulation of lipid in many cells of the theca interna by 18 h after the onset of oestrus probably reflected a reduction in steroidogenic activity; and (4) there was no evidence of any structural specialization to facilitate the transport of steroids from the theca interna to the membrana granulosa.     

Association between the alpha-ketoglutarate dehydrogenase complex and succinate thiokinase

The kinetic parameters of the individual reaction of pig heart alpha-ketoglutarate dehydrogenase complex, succinate thiokinase and the alpha-ketoglutarate dehydrogenase complex-succinate thiokinase coupled system were studied. The KCoAm of alpha-ketoglutarate dehydrogenase complex and the K-succinyl CoAm of succinate thiokinase decreased in the coupled system when compared to those of the individual enzyme reactions. This phenomenon can be explained by the interaction between the alpha-ketoglutarate dehydrogenase complex and succinate thiokinase. By means of poly(ethylene glycol) precipitation, ultracentrifugation and gel chromatography we were able to detect a physical interaction between the alpha-ketoglutarate dehydrogenase complex and succinate thiokinase. Of the seven investigated proteins only succinate thiokinase showed association with alpha-ketoglutarate dehydrogenase complex. On the other hand, succinate thiokinase did not associate with other high molecular weight mitochondrial enzymes such as pyruvate dehydrogenase complex and glutamate dehydrogenase. On this basis, the interaction between succinate thiokinase and alpha-ketoglutarate dehydrogenase complex was assumed to be specific. These in vitro data raise the possibility that a portion of the citric acid cycle enzymes exists as a large multienzyme complex in the mitochondrial matrix.     

The acinar heterotopy of phosphoenolpyruvate carboxykinase activity in rat liver under the influence of the oestrous cycle

The acinar localization of phosphoenolpyruvate carboxykinase was investigated in livers from untreated female rats during the 4-day oestrous cycle. The results were correlated with plasma levels of insulin, glucagon and oestrogens. Total activity was highest in dioestrus and lowest in metoestrus. The highest activities were present in the periportal zone and decreased continuously towards the perivenous zone in all four phases of the cycle. This general pattern was modified under the influence of the cycle. The periportal-perivenous gradient was subject to cycle dependent changes, being steepest in proestrus. In addition to oestrogens the concentrations of plasma insulin also varied during the female cycle. Insulin was highest in oestrus and lowest in proestrus. Glucagon showed only minor variations. Oestrogen concentrations increased continuously from low values in oestrus to high values in proestrus. These changes were directly related to the changes in the slope of the activity gradient.     

A quantitative cytochemical study of glucose-6-phosphate dehydrogenase and Δ 5-3β-hydroxysteroid dehydrogenase activity in the Membrana granulosa of the ovulable type of follicle of the rat

Summary During the last four days of follicular development prior to ovulation, the activities of ⁵-3-hydroxysteroid dehydrogenase (3OHD) and glucose-6-phosphate dehydrogenase (G-6-PD) were quantified in cryostat sections of the rat ovary. The product of the enzyme reactions were measured using a scanning and integrating microdensitometer. The enzyme activity was measured in the peripheral region, the antral region and the cumulus of the membrana granulosa (MG) of these follicles on the morning of each of the four days of the estrous cycle. G-6-PD activity was measured in the presence and absence of an intermediate hydrogen acceptor, phenazine methosulphate, to provide a measure of the quantity of Type I and Type II Hydrogen (H) generated: Type I H is considered to be related to hydroxylating reactions such as those of steroids and Type II H to other general biosynthetic activities of cells.In all three regions of the MG of follicles of the ovulable type, 3OHD activity was lowest in estrus and diestrus-1, increased on diestrus-2 and peaked in proestrus. In estrus and diestrus-1, the level of 3OHD activity in the three regions was comparable. However, by diestrus-2, and even more conspicuously in proestrus, enzyme activity was significantly greater in the peripheral region than in the antral region or in the cumulus. During the same period, the level of enzyme activity remained comparable in the last two regions. Throughout the estrous cycle, both Type I and Type II H generation from G-6-PD was greatest in the peripheral region, less in the antral region and least in the cumulus. In the peripheral region, Type I H generation increased progressively after diestrus-1, to reach a maximum in proestrus. In the antral region, Type I H generation increased between diestrus-1 and diestrus-2 and then remained unchanged through proestrus. In the cumulus, Type I H generation remained at levels seen in estrus throughout the remainder of the cycle. Generation of Type II H, in the peripheral region was constant throughout the estrous cycle. In contrast, in the antral region and cumulus, Type II H generation was greater in diestrus-1 and diestrus-2 than on either proestrus or estrus.This work was supported by research grants from the National Institute of Child Health and Human Development (# HD-12684) and (# HD-09542) and from the Rockefeller Foundation     

Fibre-optic spectrophotometry of immature bovine skeletal muscles and the cellular distribution of myoglobin and succinate dehydrogenase

Summary Samples of diaphragm and pectoralis profundus were taken from nine calves with a range of blood haemoglobin levels of 4 to 8.5 g/100 ml. In both muscles, fibres with strong succinate dehydrogenase activity contained myoglobin, but in the pectoralis there were many fibres with strong alkaline ATPase activity and weak succinate dehydrogenase activity that had low or undetected levels of myoglobin. The whole cross-sectional area of individual fibres was scanned to map the distribution of succinate dehydrogenase activity. Among fibres with similar levels of ATPase activity, those from the diaphragm had greater succinate dehydrogenase activity than those from the pectoralis. Subsarcolemmal succinate dehydrogenase activity was greater than the axial succinate dehydrogenase activity, and radial gradients of succinate dehydrogenase activity were steepest in the diaphragm. For pectoralis fibres with weak ATPase, the mean and the axial succinate dehydrogenase activities were correlated with blood haemoglobin levels (r=0.62 and r=0.61, respectively;P<0.05 with a Student'st-test). Muscle colour was measured directly by fibre-optic spectrophotometry and correlations of absorbance with succinate dehydrogenase activity were obtained. Absorbance at 620 nm 24 h post-mortem was correlated with succinate dehydrogenase activity in pectoralis fibres with weak ATPase (r=0.81;P<0.005).     

Effect of vagotomy on glycogen content, succinate dehydrogenase, cytochrome-c-oxidase and lactate dehydrogenase activities in myocardium in experimental aortostenosis

The glycogen contents, succinate dehydrogenase, cytochrome-c-oxidase and lactate dehydrogenase activities in tissues of cardiac left cavity of vagotomized and nonvagotomized rabbits were studied two days and two weeks after aortostenosis and false operation. It is established that in vagotimized rabbits the prolongation of the hyperfunction period causes a less pronounced decrease in the glycogen level and a higher level of the succinate dehydrogenase and cytochrome-c-oxidase activities. A conclusion is drawn that heart hyperfunction under conditions of vagotomy is accompanied by a less pronounced inhibition of aerobic and insignificant intensification of anaerobic oxidation processes as compared to their changes in rabbits with the heart maintained innervation.     

The dynamics of the histochemical activity of the oxidoreductases in the myocardium of mature and old rats undergoing whole-body gamma irradiation at a dose of 1 Gy

The effect of gamma radiation (1 Gy) on redox enzyme activity in heart cells of adult and old rats was studied during a month following the exposure. It was shown that the activity of diaphorases and succinate dehydrogenase decreased whereas that of other tricarboxylic acid cycle enzymes and lactate dehydrogenase underwent phase changes.     

The fine structure of the cumulus oophorus during follicular development in sheep

Summary The cumulus and membrana granulosa of non-atretic ovarian follicles from primordial up to a stage shortly before ovulation were studied by electron microscopy.The follicular cells of primordial follicles were undifferentiated and rested on a thick basal lamina. In secondary follicles the endoplasmic reticulum had proliferated forming an anastomosing network. In early antral and antral follicles (0.5–2.0 mm dia.) the ER was composed of short cisternae, the mitochondria had elongated and gap junctions were first observed. In late antral follicles (3.0–5.9 mm dia.) gap junctions were frequent. In the cumulus the glycogen was associated with electron lucent areas whereas in the granulosa it was invariably associated with membranes. In large antral follicles large membrane bound bodies were present in the basal cells of the cumulus. At early oestrus a distinctive mitochondrial morphology was noted in the granulosa but not elsewhere in the follicles. At mid oestrus numerous annular nexuses were present in the granulosa but not in the cumulus. At late oestrus numerous lipid droplets were formed in both cumulus and granulosa, the boundary with theca interna became indistinct and the basal lamina became incomplete.Deceased