摘要:

AbstractFresh pullet eggs (White Leghorn) were incubated for 36 to 48 hours. The blastoderms were exposed to cytochalasin B (CB), 10 or 40 μg/ml, for 2, 5, and 15 minutes prior to fixation by immersion in buffered chick Ringers solution containing CB, previously dissolved in dimethysulfoxide (DMSO), or by sub‐blastodermic injection. Controls fixedin ovopossess relatively flat surfaces with bulges due to uptake of yolk. Numerous microappendages (blebs, microvilli and ruffles) are present, especially at cell margins. DMSO‐controls present a similar cell surface except that small blebs are more prominent. The plasmalemmas of CB‐treated endodermal cells possess numerous large blebs (2‐10 μm in diameter), smaller blebs (0.2 μm) and microvilli. Cell dissociation occurs in selected areas resulting in rounded cells, devoid of microappendages, with peripheral processes. Transmission electron microscopic preparations of tissues similar to those used for scanning electron microscopy reveal that large blebs are filled with membranous material. Microfilaments are present but lack their normal subplasmalemmal arrangement. Microtubules and other cell organelles are apparently unaffected by CB. Evidence in this study supports the concept that cytochalasin B exerts its influence through alteration of the p

ISSN:0002-9106    

DOI:10.1002/aja.1001510202

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe morphology and vascular relations of tanycytes in the walls and floor of the third ventricle (3rd V) of neonatal rats (4–10 days of age) were studied with a modification of the rapid Golgi method (Valverde, '70). Serial frontal sections through the infundibular recess revealed that tanycytes may be assigned to two distinct populations based on location and structure. Tanycytes in the ventral one third of the walls as well as the floor of the third ventricle comprise the first group. The cell body of these tanycytes was subependymal in location and possessed two main processes. A centrally directed short neck‐process abutted upon the ventricular lumen and often exhibited one or more protrusions extending into the cerebrospinal fluid (CSF). Issuing from the opposite pole of the cell body, a second smooth, relatively unbranched tail process either projected directly to the ventral surface of the brain or terminated in contact with capillaries of the median eminence. A second group of tanycytes was located more dorsally in the walls of the third ventricle. The somatic apical surface of this group generally abutted directly upon the ventricular lumen and exhibited protrusions of diverse configuration projecting into the ventrical lumen. Tanycytes of the latter group were also characterized by a tortuous tail‐process which arched laterally and ventrally to terminate either in the adjacent neuropil or at the surface of the brain. Unlike those of the ventral group, these processes exhibited numerous appendages, varicosities and side branches, many of which ended as expansions in direct contact with blood vessels. In addition, segments of beaded afferent fibers of fine caliber were often seen to contact processes of both groups of tanycytes. The observed relationships between CSF, tanycytes and blood vessels support recent hypotheses of tanycyte involvement in neuroendocrine regulation, CSF composition and neuronal metab

ISSN:0002-9106    

DOI:10.1002/aja.1001510203

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe endoplasmic reticulum (ER) was stained selectively by a sequence of uranyl acetate, lead and copper citrate, according to the method of Thiéry and Rambourg ('76), and then investigated in 0.5 to 2.0‐μm‐thick sections with the transmission electron microscope. Examination of photographic stereopairs allowed a three‐dimensional visualization of the ER at various steps of spermiogenesis.During the Golgi and cap phases of spermiogenesis (steps 1–7, classification of Leblond and Clermont, '52a), the ER is distributed throughout the cytoplasm as a three‐dimensional network of spherical and tubular cisternae connected by narrow tubules. In addition, a close network of tubular cisternae is located along the convex surface of the Golgi apparatus and lines the plasma membrane. Where the cell membrane joins that of another spermatid to form an intercellular bridge, this network extends across the bridge.During the acrosome phase (steps 8–14), the cytoplasm contains an abundant ER that shows the following modifications: (A) Along the inside and outside of the caudal tube the cisternae form long tubes or plates which run adjacent and parallel to the microtubules. These cisternae are connected by delicate lateral anastomoses; (B) Along the flagellum the ER forms a “fenestrated sleeve” made up of a close network of tubular cisternae; (C) Similar networks are organized as “fenestrated spherules” enclosing large vesicles seen throughout the cytoplasm; (D) At a short distance from the flagellum, the ER cisternae are continuous with a stack of annulate lamellae and an aggregate of radially arranged collapsed cisternae called the “radial body”.During the last or maturation phase (steps 15–19), the ER regresses. Thus, during the final steps in the formation of the flagellum, the ER network fragments and then most of the cisternae disappear from the cytoplasm. The “radial body” is the last element of the ER to be dissolved. Thus the ER undergoes extensive structural modifications during spermiogenesis, suggesting an active contribution of this organelle to the differentiation of th

ISSN:0002-9106    

DOI:10.1002/aja.1001510204

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

年代:1978

数据来源: WILEY

摘要:

AbstractTwo months after blinding hamsters, the seminiferous epithelium had undergone pronounced involution. Spermatogonia were the only germ cells consistently present in the seminiferous tubules, although some tubules also contained primary spermatocytes. The peritubular tissue in the blinded hamster had undergone marked distortion. Irregular projections extended from the myoid cells and protruded toward the seminiferous epithelium. All layers of the peritubular tissue developed irregular contours and underwent thickening. The myoid cell nuclei were highly infolded, giving the nucleus a lobulated appearance. Golgi stacks often occupied recesses in the cytoplasm created by nuclear folding. Numerous vesicles were located at the poles of the Golgi stacks and were scattered between the Golgi stacks and the plasmalemma. Vesicles were also observed fusing with the plasmalemma. Alkaline phosphatase was localized cytochemically in the Golgi apparatus and the myoid cell vesicles. The appearance of the myoid cells in the involuting testes was similar to that of contracting smooth muscle; therefore, we postulate that the cytological alterations observed in the myoid cells may be a result of myoid cell contractions. Myoid cell vesicles have previously been thought to selectively take up substances at the interstitial surface of the myoid cell, transport the material across the cytoplasm and release their contents at the surface adjacent to the seminiferous epithelium. The findings reported in the present investigation indicate that some of these vesicles are involved in exocytosis of substances synthesized in the myoid cell. It appears that myoid cell exocytosis may be involved in formation of the alkaline phosphataserich basal laminae of the peritubular tissue.

ISSN:0002-9106    

DOI:10.1002/aja.1001510205

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

年代:1978

数据来源: WILEY

摘要:

AbstractPeyer's patches in normal adult mice, neonatally thymectomized mice and mice injected with hydrocortisone were studied qualitatively and quantitatively by light microscopy. The patch was divided into germinal center, follicular area, parafollicular area and dome area. In normal mice, the volumetric ratio of the germinal center to the entire patch was 30.9%; that of the follicular area, 33.3%; that of the parafollicular area, 27.7%; and that of the dome area, 8.2%. Thymus‐dependent small lymphocytes were 40% of small lymphocytes in the patch. Out of the total thymus‐dependent small lymphocytes in the patch, 13% were included in the germinal center; 19%, in the follicular area; 62%, in the parafollicular area; and 6%, in the dome area. Hydrocortisone‐sensitive small lymphocytes were 65% of the total small lymphocytes in the patch, the germinal center contained 9%; the follicular area, 84%; the parafollicular area, 2%; and the dome area, 5%. The epithelium over the dome area was invaded by numerous small lymphocytes. Forty‐eight percent of lymphocytes within the epithelium over the dome were thymus‐dependent and 67% were hydrocortisone‐sensitive.It is concluded that Peyer's patch may be considered as a peripheral lymphatic tissue, functionally as well as morp

ISSN:0002-9106    

DOI:10.1002/aja.1001510206

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe blood vessels in the gill filaments of lamprey,Lampetra japonica, were studied with an electron microscope. Each gill filament is supplied by an afferent filament artery (afa) flanked by a pair of filament veins (fv), along the outer border of the axial plate, and an efferent filament artery (efa) along the inner, free border. Between these arteries are interposed the cavernous body and the blood lacunae. The marginal channel arises from the cavernous body, which leads to the afa, runs along the free border of the secondary lamella collecting oxygenated blood from the lamellar blood lacunae, and finally joins efa. This channel is considered to play an important role in the gill circulation as a bypass between afa and efa. Pillar cells were found only in the blood lacunae of the axial plate and the secondary lamellae. The basal lamina is generally absent on the vascular wall, but only a small amount of dense material could be seen on the basal surface of endothelial cells of afa and fv: this is regarded as an anchoring device between the cell and connective tissue fibrils. Fenestrations are generally absent in the endothelial layer but numerous gaps were seen in the wall of fv. Arterio‐venous anastomoses were found between afa or the cavernous body and fv, and between efa or the collecting arteries of the efferent branchial artery and the peribranchial venous sinus. The anastomosing channel consists of the inner endothelial layer and the outer smooth muscle layer, which is thicker in the intermediate portion of the channel. The endothelial cells called “AVA cells” here are characterized by (1) dense cytoplasm, (2) apical microvilli and (3) basal cytoplasmic processes closely associated with smooth muscle

ISSN:0002-9106    

DOI:10.1002/aja.1001510207

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe gastroesophageal region was reconstructed from the histological analyses of five human newborn infants. In addition, the musculature of eight (3 newborn and 5 adult) human stomachs obtained from autopsies, with the lower one‐third of the esophagus attached, was dissected with the aid of a binocular dissecting microscope.The muscularis mucosae, in the region of the gastroesophageal junction, exhibited no increase in thickness, nor was there any indication of special mucosal folds. In addition, the gastroesophageal junction contained no morphologic evidence that would support the existence of an anatomic sphincter (a localized thickening of circular muscle fibers). However, the obliquely arranged inner circular muscle fibers of the esophagus separated into fascicular bundles below the esophageal opening. Some of the fasciculi, as they descended, again became circular in shape and continued into the stomach, forming the middle circular muscle layer, while other fasciculi maintained their oblique course toward the left surface of the esophagus. These fasciculi, coursing on the anterior and posterior surfaces of the esophagus, crossed and interdigitated along the left surface of the esophagus in the region of the incisura cardiaca. After crossing, the oblique fasciculi descended into the stomach forming the inner oblique muscle layer. Based upon this description of crossing and interdigitating fasciculi, it is suggested that closure of the gastroesophageal junction may be due to contraction of spirally arranged muscle. Since the term “sphincter” generally implies a circular structure, it is proposed that the term “spiral constrictor” be considered in naming this anatomical ar

ISSN:0002-9106    

DOI:10.1002/aja.1001510208

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe hypophysial portal vessels and anterior pituitary gland of adult male Wistar rats were exposed surgically. A hypophysial portal vessel was cannulated and infused for one minute with saline or thyrotrophin (TRH). Anterior pituitary glands were collected at 1, 5, 15, 30, or 60 minutes after cessation of infusion, for light and electron microscopic examination. Before and immediately after cannulation of a portal vessel, a 1‐ml sample of blood was collected at 1, 5, 15, 30, or 60 minutes, from the femoral vein for radioimmunoassay (RIA) of growth hormone. Thyrotrophs from anterior pituitary glands of rats infused with TRH displayed emiocytic activity at all time‐periods studied. Rough endoplasmic reticular (RER) cisternae were dilated at 15 minutes following infusion and remained dilated at 30 and 60 minutes. TRH was observed to stimulate emiocytic activity in most pituitary cell‐types. Extensive dilations of RER cisternae were also observed in mammotrophs and gonadotrophs, but were not observed in somatotrophs or adrenocorticotrophs. The demonstration that thyrotrophs, mammotrophs, somatotrophs, and gonadotrophs respond to TRH suggests that some common features may be shared by these cells. Preliminary analysis of the RIA data show that TRH was potent in elevating radioimmunoassayable growth hormone levels. Significant increases (p<0.02) in plasma GH levels were present at the earlier time periods studied (1, 5, and 15 minutes) following the infusion of TRH, but not at 30 or 60 minutes. These findings provide additional support for the non‐specific action of TRH upon the various adenohypophysial cell types, and demonstrate that TRH stimulates these cells by a direct action on the adenohyp

ISSN:0002-9106    

DOI:10.1002/aja.1001510209

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

年代:1978

数据来源: WILEY

摘要:

AbstractMandibular bone from eight patients who had received therapeutic radiation (6,000–7,200 rads) for intra‐oral cancer was obtained at surgery (1 month to 9 years after radiation) and compared histologically with non‐irradiated mandibular bone from five subjects. Measurements made on the nternal remodeling process of cortical bone included the extent of internal surface and the fraction indicating resorption, and the proportions of osteones which were incomplete (less than 3/4 filled with matrix), complete, and plugged. Appreciable differences were observed in all parameters except plugged osteones. The findings suggested early cessation of osteogenesis, and somewhat later cessation of resorption, without subsequent resumption of either process. The histologic appearance of the osteoblasts, osteoclasts, and osteones was in accord. Microfractures found in the irradiated bone were not seen to have healed. Radiation damage to the osteoprogenitor cells is postu

ISSN:0002-9106    

DOI:10.1002/aja.1001510210

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

年代:1978

数据来源: WILEY

摘要:

AbstractFour of the five kinds of cells constituting the walls of thyroid cysts can be identified in the SEM. These are cuboidal cells, mucous cells, cells with large granules and ciliated cells. A correlation between SEM and TEM observations is attempted.

ISSN:0002-9106    

DOI:10.1002/aja.1001510211

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

年代:1978

数据来源: WILEY