摘要:

AbstractThe maturation and mineralization of deer antler cartilage were investigated ultrastructurally by using enzymatic digestions and subsequent staining with ruthenium red (RR) or phosphotungstic acid (PTA).RR staining of matrix granules was observed in the immature prechondroblastic matrix and became more intense as the cartilage matured into a mineralized tissue. The granules got larger and more numerically dense in the mature matrix. There were matrix granules that coalesced around matrix vesicles or remnants of such in the mineralized zone. These granules were observed after demineralization, and they were RR and acidic PTA‐positive (they were not susceptible to hyaluronidase nor trypsin digestion, however). It appears that the granules were modified such that the matrix vesicle formed a centralized nidus for mineralization. The growth of hydroxyapatite crystals along matrix granules (which in this zone may or may not represent proteoglycan monomers) may have caused the coalescence.Microfibrils associated with matrix granules probably represented the hyaluronic acid core of the large proteoglycan complexes because of their susceptibility to hyaluronidase digestio

ISSN:0002-9106    

DOI:10.1002/aja.1001660102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractCarbonic anhydrase (CAH) activity was biochemically measured and histochemically localized (at both the light and electron microscope levels) in isolated opercular membranes from teleost fish,Fundulus heteroclitus, adapted to freshwater (FW), seawater (SW), and double‐strength seawater (2 × SW). The normal morphology of this membrane showed that its epithelial portion consisted of five cell types: (1) chloride cells, which have been previously implicated as responsible for the active chloride transport across the epithelium; (2) mucous cells; (3) pavement cells, which formed the major portion of the free epithelial surface; (4) supportive cells, which had an abundance of intermediate (10 nm)‐type filaments suggesting a structural role for these cells; and (5) vesicular cells, which were characterized by various types of membrane‐bound vesicles, including lysosomes, and numerous free ribosomes. Vesicular cells may be stem cells and/or endocrine cells. Hansson's histochemical method for CAH revealed cobalt sulfide reaction product confined to the following structures in fish from each environment: (1) chloride cells: throughout the cytoplasm and some nuclear staining; (2) mucous cells: throughout the cytoplasm, some nuclear staining, and some in mucous granules; (3) vesicular cells: confined to lysosomes, some of the vesicles, and nucleoli; (4) a small portion of the intracellular space between adjacent vesicular cells and supportive cells; and (5) supportive cells: in nucleoli and occasionally in larger membrane‐bound lysosomelike structures. Acetazolamide (10−5M) and potassium cyanate (KCNO) (10−1M) in Hansson's incubation medium completely inhibited the formation of reaction product. Biochemical determination of CAH activity on vascularly perfused, isolated opercular membranes showed no statistically significant difference in enzyme activity between environmental groups. The following units of activity/mg opercular membrane protein were measured: FW: 0.63 ± 0.02; SW: 0.43 ± 0.08; 2 ×

ISSN:0002-9106    

DOI:10.1002/aja.1001660103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractOvaries from 63 bandicoots (Isoodon macrourusandPerameles nasuta) were collected in order to obtain Graafian follicles close to ovulation for light and electron microscopy. During the first 42 days of lactation (lactation c. 60 days), the follicles were less than 1.0 mm in diameter, whereas from 43 to 52 days, some animals had follicles up to 2.0 mm in diameter, or ovulation had occurred and new corpora lutea were present. This ovulation was associated with the lactation estrus that occurred in some animals.In general, the largest Graafian follicles of the bandicoots were morphologically similar and resembled those of many other mammals. These follicles protruded from the surface of the ovary and revealed a conspicuous theca interna. The granulosa cells exhibited an unusual feature in that they contained masses of glycogen, often associated with lipid droplets and filaments.The oocytes were similar in size (diameter c. 150 μm) to those of some other marsupials and were surrounded by a zona pellucida and cumulus cells attached to the granulosa layer. The cumulus cells did not form a corona radiata as in eutherian mammals. The oocyte nuclei were somewhat flattened, peripherally located and similar in size (c. 40 × 19 μm) to those in other marsupials. These nuclei, which stained lightly with Azure A and were electron‐lucent and homogeneous, were unusually irregular in contour. The nuclei were unique in that nucleoli were always absent. Small cytoplasmic bodies which may have been extruded nucleoli were found in the oocytes ofI. macrourus, but not inP. nasuta.The cytoplasm in the bandicoot oocytes resembled that of other marsupials and some eutherians in that it was highly vacuolated with most of the organelles concentrated peripherally. Within the central region of the bandicoot oocytes there were crystalloids which were similar to those in oocytes of primordial follicles and in unilaminar blastocysts ofI. macro

ISSN:0002-9106    

DOI:10.1002/aja.1001660104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe contribution of the inferior endocardial cushion of the atrioventricular canal to cardiac septation and to the development of the atrioventricular valves was studied in the chick embryo by in vivo labelling techniques. The study was performed in White Leghorn chick embryos in which the dorsal cushion was labelled at stage 20‐21 (Hamburger and Hamilton, 1951), when the endocardial cushions were not yet fused. The embryos were sacrificed at stage 35 (mature heart).These experiments allow us to conclude that the inferior atrioventricular cushion gives origin to: (a) that part of the cardiac septum between the septal insertion of the antero‐septal leaflet of the mitral valve and the fibrous ridge which is the equivalent to the human septal leaflet of the tricuspid valve (atrioventricular septum); (b) the region of the interatrial and the interventricular septa adjacent to the atrioventricular septum; (c) the portion of the antero‐septal leaflet of the mitral valve which inserts into the septum; (d) the fibrous ridge corresponding to the septal leaflet of the tricuspid valve.Microdissection shows that, when they appear at stage 18, the superior and inferior endocardial cushions of the atrioventricular canal are in continuity, without boundaries, with both the interatrial and interventricular septa. Therefore, each atrioventricular orifice opens into its corresponding ventricle, there being no stage in the development of the chick embryo heart in which the atrioventricular orifices are connected to the left ventricle at the same time.The development of the atrioventricular canal is similar in the chick and

ISSN:0002-9106    

DOI:10.1002/aja.1001660105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractFollowing total thyroidectomy, a small quantity of thyroid tissue was transplanted to the spleen in order to study thyroid tissue subjected to chronically elevated levels of endogenous thyrotropin (TSH). Plasma thyroxine (T4) and TSH levels were monitored and correlated with ultrastructural studies of the tissue over a 32‐week experimental period. The effects of administration of an iodine‐poor diet, an exogenous acute dose of TSH, and suppression of endogenous TSH through thyroxine administration were studied in order to evaluate the plasticity of the experimental model.Plasma T4decreased after the first week and remained at approximately one half of the initial value until 12 weeks. Plasma TSH increased to a high of 6,220 ng/ml after 6 weeks and gradually declined to one half of that value. The transplanted tissue remained functional throughout the experimental period. The number of pseudopods decreased, and irregularly shaped, dense bodies increased from the time of surgery until 12 weeks later. Administration of an acute dose of TSH at this time resulted in obvious mitotic activity and the formation of numerous pseudopods. The tissue also maintained the ability to take up radioactive iodine and to iodinate thyroglobulin. Inhibition of TSH secretion through T4administration from the time of surgery did not affect viability. Some cellular hypertrophy persisted after 32 weeks although TSH and T4had returned to normal.This study has shown that thyroid tissue remains viable, functional, and experimentally alterable throughout an extended period of chronic stimulation by endogenous TSH, and that it has the reserve capacity to secrete normal levels of T4at the end of this experimental per

ISSN:0002-9106    

DOI:10.1002/aja.1001660106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of a single diabetogenic dose of alloxan on the ameloblasts of enamel secretion was investigated in rat incisor teeth prior to the onset of diabetes mellitus. This was compared with tissue from animals that were sacrificed at the onset of diabetes, and with tissue from animals that had been diabetic for 1 month. Male Sprague‐Dawley rats were given a single subcutaneous injection of alloxan at a dose of 150 mg/kg body weight; and the animals were sacrificed at 45 minutes, 2 hours, 24 hours, 48 hours and 29 days after injection. At the electron microscope level the following changes were observed. There was an early accumulation of secretion granules in the vicinity of the Golgi apparatus and within the proximal portion of Tomes' process. These accumulations were present at the onset of diabetes, 24 hours later. At 2 hours after injection a space appeared between the plasma membrane around Tomes' process and the interrod material. This space widened with time, and at 24 hours after injection it became continuous with enlarged intercellular spaces between the proximal portions of Tomes' processes. The widening of the intercellular space was restricted to the area above the distal cell web. At the onset of diabetes this compartment of the cells was similar to that of the control samples. Extracellular material which appeared to be the secretory product of the ameloblast was observed at two sites. On one occasion this material was seen in the wide intercellular spaces between the proximal portions of Tomes' processes 24 hours after injection. It was also seen at the onset of diabetes in the intercellular space at the level of the Golgi apparatus. The changes in the animals that had been diabetic for 1 month were a scarcity of secretion granules within Tomes' processes and an abnormal accumulation of secretion granules within the supranuclear and infranuclear compartents.This study has shown that the toxic effect of alloxan persists up to the time of onset of diabetes mellitus. However, since different morphological changes were observed during diabetes mellitus, it is suggested that the changes caused by diabetes are a separate entity, initially superimposed on and later replacing the acute, toxic effect of the dru

ISSN:0002-9106    

DOI:10.1002/aja.1001660107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractUnlike the mandibular condyle, the temporal component of the temporomandibular joint (TMJ) has been the object of relatively few investigations concerning its growth and remodeling. This report provides qualitative and quantitative documentation of microanatomical changes in the mandibular fossa and articular eminence during growth of the rhesus monkey (Macaca mulatta). The thickness of the fibrous articular tissue and the presence of cartilage cells in its deeper layers were examined histologically in 43 rhesus monkeys at five maturational levels (neonate, infant, juvenile, adolescent, and young adult). Absolute thickness of the articular tissue increased with maturational level in all areas studied, with the increase somewhat more pronounced on the posterior slope and crest of the articular eminence than in the roof of the mandibular fossa. Relative to condylar size, an increase in articularlayer thickness characterized the first three maturational levels, and was followed by a decrease during adolescent and young‐adult stages. Articular tissue in the fossa roof constituted a steadily decreasing fraction of the total articular‐tissue thickness with age, while relative thickness of the tissue on the posterior slope and crest of the eminence increased with age. These results parallel those obtained for the mandibular condyle, and they are best interpreted to indicate that forces delivered to the joint become directed more anteriorly with age. The overall pattern of topographical variation in articular‐tissue thickness and cartilage‐cell distribution suggests that greater loading of the lateral aspect of the TMJ, postulated in the human TMJ by various workers, may not be as pronounced in the

ISSN:0002-9106    

DOI:10.1002/aja.1001660108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001660101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY