摘要:

AbstractIn all species studied, the upper two‐thirds of the third ventricle is lined by ependymal cells with a profusion of long cilia that extend into the lumen. In the rabbit, rat, and mouse, an abrupt transition to a sparsely ciliated ependymal surface occurs along the lower one‐third of the ventricular wall, at the level of the underlying ventromedial (VM) nucleus. Unique to the rat transition zone however, is a predominance of microvilli. In the human, a subtle transition to a sparsely ciliated ependymal surface occurs somewhat higher at about the level of the underlying dorsomedial (DM) nucleus. Along the upper expanse of the rabbit infundibular recess (IR) ciliary bundles are infrequent, although occasional solitary cilia are seen. The characteristic features of this region, however, are the non‐ciliated ependymal cells with their many irregular bleb or microvilli‐like surface protrusions. In contrast to the rabbit, the same region in the rat and mouse is distinguished by an irregular ependymal surface with stout bleb‐like protrusions and many single cilia. Similarly in the human, cilia become progressively fewer toward the IR. Although the non‐ciliated epen‐dymal surface in this region resembles that of the rabbit, the surface blebs and microvilli‐like protrusions are fewer in number and less prominent. The lateral walls of the third ventricle display a consistent regional variation in the morphology of the luminal ependymal surface in all species studied. Although it is not possible to establish unequivocally the nature or significance of these regional differences, the structural modifications of the ependymal surface in the region of the IR are entirely consistent with the secretory or absorptive function attributed to ependy

ISSN:0003-276X    

DOI:10.1002/ar.1091740402

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe pattern of arterial supply to the cat's lumbosacral spinal cord was examined in a dozen latex‐injected specimens with a view to determining what precautions might be taken in the procedure of rhizotomy to minimize embarrassment of the cord's circulation. The single ventral spinal artery was found to receive on an average 4.1 significant radicular contributions, of which one or two arteries at the fourth or third lumbar levels on the left were invariably of especially large size. Equal numbers, about six to eight, of contributions to the two dorsolateral arterial trunks were present. Anastomotic channels greater than 50 m̈ in diameter were rather poorly developed between dorsolateral and ventral arterial channels, especially across the middorsum. The dorsal radicular artery in 82 of 97 roots examined was seen to pierce the ventral root in order to reach a position along the ventral aspect of the dorsal root. In most cases this penetration occurred central to the ganglion. The bearing of this feature on reported differences in behavioral effects from rhizotomy by intradural section and by ganglionectomy is discussed, as well as other aspects of the effect of rhizotomy on cord criculati

ISSN:0003-276X    

DOI:10.1002/ar.1091740403

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

年代:1972

数据来源: WILEY

摘要:

AbstractBased on differences in light absorption the stages of the rat seminiferous epithelial wave were identified by a transillumination technique. The most marked difference was encountered in the boundary between stages VIII and IX where the mature spermatozoa are released into the tubular lumen. Other characteristic transitions were observed between stages VI and VII as well as stages XII and XIII. All stages could be divided into four major, easily recognizable zones. Within the zones the stages could be identified with an accuracy of ± 1 stage. The characteristic changes take place in the tubular center and are due to the development of the acrosome in the spermatid. The acrosome appears to contain material with a strong light absorption capacity.Based on these observations a method was developed to isolate identified fragments of the rat seminiferous tubule in native condition. These fragments were used to quantify the activity of three previously described enzymes: specific tubular acid phosphatase III and IV as well as aminopeptidase III.The tubular acid phosphatase IV showed a high activity in stages corresponding to the final maturation process of the spermatid, whereas acid phosphatase III was evenly active in the different stages. Also aminopeptidase III showed a peak of activity during stages V‐VII coincident with that of acid phosphatase IV, The possible role of these enzymes in the morphological maturation of spermatid and the destruction of the residual body is discuss

ISSN:0003-276X    

DOI:10.1002/ar.1091740404

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

年代:1972

数据来源: WILEY

摘要:

AbstractChronic hyperthyroidism was induced in radiothyroidectomized and surgically thyroidectomized adult male rats by feeding a diet of 0.3–0.4% desiccated thyroid for four to ten week periods. Short term hyperthyroidism was induced in intact rats by the intraperitoneal injection of 250 μg/day of sodium levothyroxine for ten days. Adrenal glands were fixed by perfusion with 3% phosphate buffered glutaraldehyde and post‐fixed in 1% osmium tetroxide. The zona fasciculata of the adrenal glands from experimental and control animals was examined in the electron microscope. Drastic mitochondrial alterations characterized the zona fasciculata of hyperthyroid rats. Initially, mitochondria became more nearly round and contained increased numbers of paracrystalline tubular inclusions of the type described by Kjaerheim ('67) and Wheatley ('68). In more altered states many mitochondria were filled with clusters of parallel tubular cristae of varying complexity which at times enveloped islands of mitochondrial matrix and fingers of cytoplasm which projected into the mitochondrion. Aggregations of numerous mitochondria occupied much of the cytoplasm of highly altered cells. Modifications of this nature have not been described following ACTH stimulation of the adrenal cortex. This raises the distinct possibility that thyroid effects on the adrenal cortex are not entirely ACTH medi

ISSN:0003-276X    

DOI:10.1002/ar.1091740405

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

年代:1972

数据来源: WILEY

摘要:

AbstractMacrophages associated with the subarachnoid space have fine structural characteristics which distinguish them from macrophages found elsewhere. The specific location of a macrophage in this area influences its morphology. Macrophages found in the subarachnoid space characteristically have a highly vacuolated cytoplasm. When cells of the pia mater separate the macro‐phage from the subarachnoid space, the extreme vacuolization is not present and a more compact cytoplasm prevails. Frequently macrophages found in the median longitudinal fissure contain compound reticulated inclusions. Extracellular bodies resembling compound reticulated inclusions have been observed.The presence of lobulated nuclei, lysosome‐like inclusions, phagosomes, and other characteristics of these cells is reported. The possible origin and function of subarachnoid space macrophages is discus

ISSN:0003-276X    

DOI:10.1002/ar.1091740406

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe fine structure of the rat testis was studied at intervals of up to nine months after bilateral vasectomy, unilateral vasectomy, or a bilateral sham operation. Objectives were to determine whether the fine structure of the testis is altered as a result of vasectomy and to determine if any of the sperm produced after vasectomy are retained and disposed of within the testis. Attention was directed toward the ultrastructure of developing spermatids, the cytology of Sertoli cells, and the structural relationships between Sertoli cells and germ cells. No alterations in these features were detected, and it was concluded that the fine structure of the rat testis remains normal after vasectomy. Factors are discussed which may qualify this conclusion, such as the structural complexity of developing germ cells and the multiplicity of stages in the cycle of the seminiferous epithelium. Sertoli cells contained residual bodies after vasectomy, but there was no evidence that phagocytosis by Sertoli cells increased, suggesting that the main site of disposal of sperm after vasectomy lies distal to the seminiferous tubules.

ISSN:0003-276X    

DOI:10.1002/ar.1091740407

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

年代:1972

数据来源: WILEY

摘要:

AbstractThis paper considers the sampling precision of a systematic sampling method for estimating total number of nerve fibers exposed on cross section of a nerve trunk. The mean square error (MSE) associated with systematically selecting every Kth grid square (traversing the section in a serpentine pattern) was determined in each of nine nerve fiber populations and compared to the MSE obtained using a completely random selection of grid squares.For both sampling methods sampling errors of approximately 10% could be achieved by counting in 10% (K = 10) of the available grid squares. To reduce the MSE to 5% or less necessitated, for both methods, counting approximately 50% (K = 2) of the cross sectional area.Although the results of this investigation are based on the study of but one class of nerve fiber population (cervical sympathetic nerve trunks), the authors believe that certain of the results will have practical application in similar quantitative studies. More important, it is hoped that this study will motivate further investigations into the precision of sampling methods currently employed (and others which may be proposed) in the quantitative study of the nervous system.

ISSN:0003-276X    

DOI:10.1002/ar.1091740408

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

年代:1972

数据来源: WILEY

摘要:

AbstractHistochemical and autoradiographic studies using35S‐sulfate indicate that the majority of the cartilage cells in the developing mandibular condyle of the young mouse are active, vital cells. Concomitant with the increase of hypoxic conditions within the deeper layers of the cartilage, an increase in sulfated glycosaminoglucuronoglycans synthesis takes place. Hypertrophic chon‐drocytes in the premineralized and mineralized zones reveal marked35S‐sulfate uptake in comparison with the less differentiated cells in the chondroblastic and perichondrial zones. These observations of radiosulfate activity support the concept that calcification processes in the condylar cartilage are not necessarily accompanied by degeneration and death of the hypertrophic chondrocytes. The radiosulfate activity of the surviving chondrocytes in the vicinity of the ossification front indicates possible modulation into osteoprogenitor

ISSN:0003-276X    

DOI:10.1002/ar.1091740409

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

年代:1972

数据来源: WILEY

摘要:

AbstractElectron microscopic observations are reported which demonstrate that ribosomes are extruded during the final stages of maturation in erythroid cells of rats and guinea pigs. Concentration of ribosomes in the cytoplasm, formation of a membrane bounded vesicle containing these ribosomes and extrusion of the vesicle are described and discussed.

ISSN:0003-276X    

DOI:10.1002/ar.1091740410

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

年代:1972

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1091740401

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

年代:1972

数据来源: WILEY