摘要:

Postnatal development of the sarcolemmal invaginations of right atrial cells of the rat has been studied using standard fixation combined with tannic acid mordanting. T tubules were seen to form at Z lines as simple tubular invaginations starting at the 14th postnatal day. T tubules were present in most cells by the 18th postnatal day but, as in the adult, were restricted to peripheral regions. Also, between the 16th and 18th postnatal day a proliferation of caveolae was seen, both as single vesicles and as complexes with up to a dozen caveolae sharing the same neck. The caveolar complexes persisted in the adult and did not seem to contribute significantly to the formation of the T tubules. Dyadic couplings were seen to become more abundant as T tubules and caveolae proliferated. These findings are discussed in relation to transsarcolemmal Ca2+ movements and excitation-contraction coupling during postnatal development.

ISSN:1422-6405    

DOI:10.1159/000145801

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The morphology and functional roles of the smooth-ended maturation ameloblasts (SAs) of rat incisors were examined by means of routine thin sections, tracer experiments, and freeze-fracture replication. SAs possessed two sets of junctional complexes consisting of tight junctions (fasiae occludentes) and gap junctions at the proximal and distal ends. Neither the proximal nor the distal junctional complex formed a complete barrier around the cell; intravenously injected horseradish peroxidase (HRP) reached the developing enamel surface through SAs extracellular spaces. SA supranuclear cytoplasm included such various cytoplasmic vesicles as the multivesicular body (MVB), large and small vacuoles, dense body, and coated vesicles. The HRP that reached the enamel surface was incorporated into some coated vesicles and small vacuoles via coated pits and membrane invaginations of the distal cell surface of SA. Then, in the process of time, it migrated into the MVB and large endocytic vacuoles. These results indicate that the SA layer forms an extracellular transfer route for metabolites between papillary layer and the enamel surface and that SAs absorb exogenous protein.

ISSN:1422-6405    

DOI:10.1159/000145802

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Mandibular shape was compared by the technique of medial axis transformation between four inbred strains of mice fed upon ‘hard’ and ‘soft’ diets. Multivariate analysis of component medial axis lengths showed the interstrain contrasts to be slightly greater between animals maintained on ‘hard’ as opposed to ‘soft’ diets. The mandibular shape contrasts primarily reflected differences of the ramus compared with the corpus, although the reasons for such changes have yet to be ful

ISSN:1422-6405    

DOI:10.1159/000145803

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The appendix epididymidis and aberrant ductules possessed similar morphological characteristics. The epithelium was 31 ± 3 µm in height and consisted primarily of ciliated and nonciliated cells, although a few lymphocytes were also present. The ultrastructure of major cell types showed most cell organelles in their cytoplasm. However, these organelles were poorly developed, suggesting that neither cell type performed either a secretory or an absorptive function. Although the vestigial organs and ductuli efferentes were similar in epithelial height and epithelial cell types, there were important morphological differences that were reliably used to differentiate between the two. First, the luminal diameter was significantly smaller in the vestigial organs (60 ± 12 vs. 146 ± 44 µm in the ductuli efferentes). Second, the nonciliated cells of the vestigial organs, unlike those of the ductuli efferentes, lacked both dense granules and vacuoles in the cytoplasm. Finally, the tubular cross-sections of the vestigial organs were closely packed and were located at the tip of the caput epididymidis in the case of the appendix epididymidis, and between the lobules of the ductuli efferentes in the case of the aberrant duct

ISSN:1422-6405    

DOI:10.1159/000145804

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Holtzman rats of both sexes were fed one of the following semisynthetic diets: 25% protein (control), 10% protein (slight malnutrition), 5% protein (medium malnutrition), and 2% protein (severe malnutrition). The skulls were cleaned and disarticulated with papain; they were defatted, dried, and the total weight (Tw) of each bone was determined. A gravimetric method of estimating bone protein-mineral ratio was performed. Following a decalcification with EDTA, the protein matrix was weighed (PMw). A protein-mineral index (PMI) was defined as: PMI = 100 (Tw-PMw)/Tw. The nutritional deficiencies imposed affected the protein and/or mineral contents of the bones according to three different patterns. The first pattern was followed by the bones of the vault and the facial region. The second one included the basicranial bones. The third one comprised the incisors. These patterns were associated with the histogenetic characteristics of the bones and teeth. A relationship between these findings and previously ascertained functional craniofacial variations in malnourished rats was found. From the differential behavior of the base, the vault, the masticatory apparatus and the incisors, it was inferred that each of these functional cranial components reacted to the experimentally unbalanced nutrition, according to a specific kind of adaptive mechanism.

ISSN:1422-6405    

DOI:10.1159/000145805

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Daily subcutaneous injections of glucocorticoid preparations have been shown to produce clinical signs of hyperadrenocorticism which resulted in interference with the growth of rats, shown by measurements both of body weight and of the length of long bones. The purpose of this study was to see if increased, intermittent, compressive forces, produced by experimental bipedalism, would mitigate the negative effects of cortisone injections on long bone growth and if there would be a difference in reaction between male and female rats. Male and female Sprague-Dawley rats were used for control, cortisone-injected, and cortisone-injected plus bipedal groups. Experimental bipedalism was produced at 10 days of age; cortisone injections began at 30 days of age; all animals were sacrificed at 65 days of age. Tibial and femoral lengths were measured. The results do not support the hypothesis that bipedalism can be instrumental in mitigating the effects of hyperadrenocorticism on hindlimb long bone growth.

ISSN:1422-6405    

DOI:10.1159/000145806

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The minor active component of bee venom was applied to mouse neuroblastoma cultures. The cytological changes observed are reported. After 8–10 h of incubation with 5 µg/ml of apamin in the culture medium, considerable retractions of the processes are apparent. Electron microscopically, the alterations seen are predominantly found in the subcellular organelles. The peculiar configuration of the endoplasmic reticulum (ER) is striking. Concentric whorls of cisternae seem to engulf the remaining ground substance. Following a 24-hour incubation with 5 µg/ml of apamin, the cell membrane disintegrates. A deeply infolded nucleus, vacuoles and remnants of cell organelles are present. The previously intact synapses are totally degenerated. Similar experiments using lower concentrations of apamin do not depict any apparent changes either light or electron microscopica

ISSN:1422-6405    

DOI:10.1159/000145807

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The secretion of insulin in response to glucose and the changes in the B cell at the ultrastructural level were studied in rat pancreas perfused at pH 7.4 and 7.8 with different concentrations of glucose. Raising the extracellular pH from 7.4 to 7.8 significantly inhibits glucose-induced insulin secretion. Coincidently, morphometric studies showed significant evidences of low secretory activity in B cells from pancreas submitted to high glucose stimulation under alkalosis, namely lower number of emiocytotic figures and microtubules as well as a decrease in the volume density of the granular endoplasmic reticulum and the Golgi complex. On the other hand, a significant increment in the number of images of granulolysis was also demonstrated. These secretory and ultrastructural results confirm the inhibitory effect of pH 7.8 upon B cell secretory activity induced by glucose. Moreover, they lend further support to the role of intracellular hormone degradation as a regulator of B cell insulin content.

ISSN:1422-6405    

DOI:10.1159/000145808

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The findings in a cadaver demonstrated: (a) an aberrant retroesophageal right subclavian artery (RRSA); (b) a thoracic duct (Th.d.) terminating at the junction of the right internal jugular and subclavian veins (‘venous angle’), and (c) a left vertebral artery (LVA) of aortic origin. The origin of the RRSA from the aortic arch was distal and medial to the left subclavian artery and it reached the upper extremity by crossing posterior to the esophagus. The Th.d. ran a normal retroesophageal course in the mediastinum, until it was intercepted by the anomalous subclavian artery. At this level the Th.d. was deflected towards the right and, accompanied by the anomalous artery, reached the right venous angle. The LVA arose from the aortic arch between the left common carotid and the left subclavian arteries, and ascended to the transverse foramen of C6. The practical importance of associations in general is discussed, and the special diagnostic and surgical significance of the RRSA and Th.d. is stres

ISSN:1422-6405    

DOI:10.1159/000145809

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The retromolar mucosa of the rat, mouse and golden hamster was observed by light and scanning electron microscopy. Numerous taste bud papillae, each of which formed a low round eminence containing one to several taste buds, were present in the posterior region of the retromolar mucosa, and were especially concentrated in the vicinity of the orifices of the molar glands. This topographical coincidence suggests that the retromolar mucosa of these animals has a functional role as a taste organ. Microridges, arranged in various patterns and small pits, were observed on the surface of the keratinized epithelium of the rat and mouse retromolar mucosa. It appears that the development of numerous microridges is adapted for varied stimuli in the oral cavity.

ISSN:1422-6405    

DOI:10.1159/000145810

出版商:S. Karger AG    

年代:1983

数据来源: Karger