摘要:

AbstractThe present work reports a tridimensional reconstruction of the intratesticular seminal pathway in the hamster as studied with light microscopy of serial sections of the proximal pole of the testis. It has three portions: a “terminal segment” of the seminiferous tubules; the tubuli recti with three parts; and the rete testis with two parts, intratesticular and extratesticular.Experiments using ductuli efferentes ligation show a marked dilation of the rete testis and tubuli recti without a corresponding dilation of the seminiferous tubules. This may be due to a valve‐like action of the cells in the terminal segment of the tu

ISSN:0003-276X    

DOI:10.1002/ar.1091870102

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe interstitial tissue of the testis of the nine‐banded armadillo is composed of blood vessels, clusters of Leydig cells, the usual connective tissue elements, and a network of lymphatic sinusoids. The endothelial walls of the sinusoids are separated from the peritubular contractile cell layer surrounding the seminiferous tubules by a thin layer of collagen. The peritubular contractile cell is characterized by filaments and dense bodies within the cytoplasm, whereas the endothelial cells lack these structures. Within each cluster, several Leydig cells surround one or more blood vessels. Adjacent Leydig cells are joined by 2‐ to 3‐nm wide gap junctions and desmosome‐like specializations. The Leydig cell is polygonal in shape with an ovoid nucleus. The cell is characterized by an abundance of smooth endoplasmic reticulum which appears as sheets of membranes, concentric whorls around vacuoles, and a random tubular network. Only a few short cisternae of rough endoplasmic reticulum are observed. Centrioles are closely associated with the Golgi apparatus. Rod‐like mitochondria with tubular cristae are scattered throughout the cytoplasm. In addition, the cells contain vacuoles resulting from lipid extraction, filaments, microtubules, and glycogen. The surfaces of the cell exposed to the intercellular spaces exhibit numerous pinocytotic vesicles and cell processes which indicate active movement of material across the plasma membrane. In comparison to other mammalian species, the ultrastructural organization of the interstitium and the fine structure of the Leydig cell of the armadillo resemble those of the g

ISSN:0003-276X    

DOI:10.1002/ar.1091870103

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe spleens of rats were studied by light and electron microscopy during the course of an acute myelogenous leukemia, with special reference to infiltration of leukemic myeloblasts in the spleens and to the correlation of leukemic cell infiltration with splenic hematopoiesis and splenomegaly. Leukemic myelo‐blasts infiltrated the cordal space of the red pulp. Many of them appeared in groups. Even in spleens which were heavily infiltrated, leukemic myeloblasts did not penetrate the white pulp. Massive infiltration and proliferation of the leukemic myeloblasts in the red pulp resulted in splenomegaly. The spleen increased its he‐matopoietic activity, while the medullary hematopoiesis diminished due to the invasion of leukemic myeloblasts in the bone marrow. Compensatory splenic hemato‐poiesis occurred in most of the leukemic spleens, but diminished in spleens which were very heavily infiltrated with leukemic myeloblasts. Thus, the degree of splenomegaly and splenic hematopoiesis did not necessarily correspond to the percentage of leukemic myeloblasts in the bone marrow, but rather related to the number of leukemic myeloblasts present in the spleen. A possible role for the splenic sinus walls in promoting compensatory hematopoiesis in the spleen is discussed. A consistent association of type “C” virus particles with leukemic myeloblasts was

ISSN:0003-276X    

DOI:10.1002/ar.1091870104

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

年代:1977

数据来源: WILEY

摘要:

AbstractWe describe morphological sex differences in urinary bladders of the urodele amphibianNecturus maculosus. The mucosal epithelial cells of bladders from males were tall and contained considerable PAS‐positive material. In scanning electron micrographs of the mucosal surface, epithelial cells from male bladders were well demarcated and were capped with microplicae or with long cilia. The mucosal epithelial cells of bladders from females were low and contained only a small amount of PAS‐positive material; in scanning electron micrographs cell boundaries could not be distinguished and no cilia or microplicae were present. Bladders from males had higher transepithelial potential difference and lower water content than bladders from females. Urine analyses were not significantly different in the two sexes. It is suggested that response to androgens in the male accounts for the observed differen

ISSN:0003-276X    

DOI:10.1002/ar.1091870105

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

年代:1977

数据来源: WILEY

摘要:

AbstractDuring renewal of the enamel organ in the rat incisor cohorts of epithelial cells are transported sequentially through presecretory, secretory and maturation zones to the gingival margin where the life cycles of these cells terminate. This process was examined kinetically by determining the absolute flux of cells within each of these zones of amelogenesis. It was found that the efflux of ameloblasts, stratum intermedium and papillary layer cells from the presecretory zone was about equal to the efflux plus expected growth within the secretory zone. However, between the secretory and maturation zones about 50% more ameloblasts entered the maturation zone than were required to account for the egress at the gingival margin and the expected growth. Since there was no similar imbalance between these zones for papillary layer cells, it was concluded that this discrepancy must represent a 50% reduction in the size of the ameloblast population during the maturation stage of amelogenesis. It was calculated that a little over 25% of the loss occurred immediately at the start of maturation within the region of postsecretory transition and the remaining 25% of the loss occurred throughout the subsequent regions of the maturation zone. In addition to the kinetic analysis graphic reconstructions, orsurface maps, of ameloblast nuclei were prepared. These maps illustrated the characteristics of ameloblast nuclear packing within the three zones of amelogenesis and they provided quantitative confirmation that as ameloblasts progress through the maturation zone, there is a loss of cells in an amount predicted by the kinetic analysis.

ISSN:0003-276X    

DOI:10.1002/ar.1091870106

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe distribution of axons in the posterior articular nerves in rhesus monkey has been studied in terms of ratio of myelinated to unmyelinated fibers, and size of myelinated fibers. Conduction velocity measurements were also made. The nerves contained 2,000 to 2,200 unmyelinated fibers of 0.2 to 1.2 μm. diameter. They contained 399 to 478 myelinated fibers, varying in size from 1.4 to 12.3 μm. Thus 80 to 85% of fibers in these nerves were unmyelinated. The maximum conduction velocity of 70 to 80 meters per second corresponded to an initial small deflection, with most fibers conducting at slower rates. These results are compared to previous reports which severely underestimated the number of unmyelinated fibers because electron microscope counts were not utilized.It is suggested that pain fibers from the knee joint of monkey make up much of this large population of unmyelinated axons. An unknown number of post‐ganglionic sympathetic fibers is also included in the unmyelinated fiber gr

ISSN:0003-276X    

DOI:10.1002/ar.1091870107

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

年代:1977

数据来源: WILEY

摘要:

AbstractPresence of a ridge of fatty tissue running obliquely upwards and backwards over the left aspect of the pulmonary trunk was observed. It started from the left end of the infundibulo‐truncal junction and after running parallel adjacent to free anterior border of the left auricle, terminated into an expanded, oval and discoid structure, a little above the level of the tip of the left auricle. The structure was found to be of constant occurrence, position and form.A comparison between similar structure reported in relation with the aorta and the right auricle was attempte

ISSN:0003-276X    

DOI:10.1002/ar.1091870108

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

年代:1977

数据来源: WILEY

摘要:

AbstractIn this article a description of the process of spermatogenesis in the Chinese hamster is given.Spermiogenesis could be divided into 16 steps. The cycle of the seminiferous epithelium was divided into 12 stages, coinciding with the first 12 steps of spermiogenesis. The relative and absolute duration of the stages was determined. The duration of the cycle of the seminiferous epithelium was found to be 17.0 days.The morphology of the spermatogonia was studied in seminiferous tubules mounted “in toto.” Four classes of spermatogonia could be discerned: undifferentiated A spermatogonia (Ais, Apr, Aal), differentiated A spermatogonia (A1, A2, A3). In spermatogonia and B spermatogonia (B1, B2). It is interesting to note that the last generation of spermatogonia (B2) arises at the beginning of stage 7 and divides to give rise to primary spermatocytes in the second half of this stage; in most other species the last generation of spermatogonia arises in stage 4, giving rise to primary spermatocytes in stage 6.The undifferentiated A spermatogonia were counted in six stages of the cycle, together with the differentiated A, In or B spermatogonia present in the same stages. The results of these cell counts are discussed in detail. One of the conclusions that could be drawn about the behaviour of the Aisand Aprspermatogonia during the cycle of the epithelium was that there is mitotic activity in these cells in several stages of the cycle. It is suggested that this mitotic activity serves to generate the Aalspermatogonia, which after one or more divisions transform into A1spermatogonia between stages 2 an

ISSN:0003-276X    

DOI:10.1002/ar.1091870109

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

年代:1977

数据来源: WILEY

摘要:

AbstractIncubation of early embryos ofNothobranchius korthausaein sterile Tris‐buffered pronase with added salts and EDTA results in complete dechorionation, after which development proceeds normally and at the same rate as in control embryos. The time required for dechorionation varies according to the age of the embryo and the concentration of pronase employe

ISSN:0003-276X    

DOI:10.1002/ar.1091870110

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

年代:1977

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1091870101

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

年代:1977

数据来源: WILEY