摘要:

AbstractAs an anatomical region the head combines great diversity of function with close integration of structure. Consequently no structural component has autonomy of form. There is a sequence of maturation of functions and their related structural components, and in this sequence the nervous system and its supportive structures mature first. The nasal airway matures next in response to increasing body mass, and the masticatory system constitutes the last major functional system to reach maturity. The later the maturation of the function, the greater is the requirement for its related morphology to adapt to preceding skeletal templates. These matters of developmental sequence, and extrinsic as well as intrinsic craniofacial functions, are paramount considerations in interpreting the form of any component of head anatomy.

ISSN:0003-276X    

DOI:10.1002/ar.1092180202

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe acinar and islet cells of the adult mouse pancreas were examined by radioautography after continuous infusion of3H‐thymidine, for periods varying from 1 to 60 days, to determine whether they behaved like renewing or expanding cell populations. The labeling of both cell types increased with the duration of the continuous infusion and reached 2.22% and 12.0%, respectively, after 60 days. The rate of acinar and islet cell labeling was estimated from the regression line of the labeling index versus time and given as 0.039% and 0.20% cells per day, respectively.The rate of cell labeling was relatively low in these acinar and islet cells in comparison to the relatively high rate in duct cells. Occasionally, acinar cell labeling was not uniform, showing high labeling in the outer peripheral region of a lobe and at the periphery of the islets. Both acinar and islet cells increased in number in the adult, and at a rate indicating they are expanding cell populations. Their doubling times were estimated as 2,564 days (7.0 years) and 500 days (1.3 years), respectively. Duct epithelial cell populations were dividing at a rate indicating that they are renewing cell population

ISSN:0003-276X    

DOI:10.1002/ar.1092180203

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

年代:1987

数据来源: WILEY

摘要:

AbstractIsoflurane is an inhalational anesthetic agent associated with no known hepatic toxicity. Despite this fact, isoflurane has not been widely utilized as an anesthetic agent in studies of liver structure and function in experimental animals. For this reason, livers from rats treated with pentobarbital or diethylether were compared to those from rats treated with isoflurane to determine differences in biochemical and morphologic parameters.Liver from pentobarbital‐treated rats showed a significant decline in glutathione‐S‐transferase activity compared to liver from isoflurane/O2or ether‐treated rats. Liver microsomes from isoflurane/O2‐treated rats retained more cytochrome‐C(P450)‐reductase activity than did those from pentobarbital‐treated, ether‐treated, or decapitated rats. Despite these biochemical alterations, morphometric analysis of liver from isoflurane/O2and pentobarbital‐treated rats showed no quantitative or qualitative differences in liver structure or organelle volume densities. Neither were differences detected in uptake and distribution of125I‐epidermal growth factor when analyzed by electron microscopic autoradiography. These data show that isoflurane with supplemental O2has no effects on hepatic structure and fewer effects on hepatic function than other anesthetics and may be a better experimental anesthetic than

ISSN:0003-276X    

DOI:10.1002/ar.1092180204

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

年代:1987

数据来源: WILEY

摘要:

AbstractDuring enamel maturation in rodents, an iron‐containing pigment is deposited into the surface layer of the enamel. Maturation zone ameloblasts presumably are responsible for this deposition. The presence of large amounts of ferritin in the cytoplasm of these cells suggests that they receive iron, presumably from circulating transferrin. An in vivo radioautographic binding assay using iodinated transferrin was used to determine if indeed maturation ameloblasts possess transferrin receptors at their cell surfaces. Experimental rats received systemic injections of labeled transferrin while control rats received injections of labeled transferrin plus a large excess of unlabeled transferrin in order to complete with the labeled transferrin for available specific receptors. Light microscope radioautography showed that ruffle‐ended ameloblasts (RAs) of the enamel maturation zone had a high density of specific receptors for transferrin relative to smooth‐ended ameloblasts (SAs). Electron microscopy and energy‐dispersive X‐ray spectroscopy confirmed the presence of ferritin and iron, respectively, within these cells. It is postulated that the iron responsible for enamel pigmentation is transported by transferrin to maturation ameloblasts and is bound to specific transferrin receptors found mostly on RAs and that the modulation of these cells into SAs results in a loss of most of these

ISSN:0003-276X    

DOI:10.1002/ar.1092180205

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

年代:1987

数据来源: WILEY

摘要:

AbstractA cryostat retrieval method and combined adenosine triphosphatase (ATPase) and acetylcholinesterase (AChase) method were used to study the ultrastructure and innervation of histochemically identified skeletal muscle fibers in different pigeon muscles. The Z‐line structure and volume percentage sarcotubular system were analyzed from different muscles selected for their composition by fiber type. Histochemically, three main fiber types were investigated: slow tonic fibers with a moderate ATPase activity after preincubation at acid or alkaline pH; fast‐twitch fibers that had high activity after alkaline treatment and low activity after acid preincubation; and a type considered to be slow‐twitch that had low activity after alkaline, and high after acid preincubation. Both the slow tonic and slow‐twitch fibers had multiple, en grappe innervation, while the fast‐twitch fibers had robust, single end plates. The Z‐line of the fast‐twitch and slow‐twitch fibers had a regular square lattice pattern, in contrast to the granular, nonlattice structure of the slow tonic Z‐line. The volume percentage sarcotubular system of the slow‐twitch fibers was intermediate between and significantly different from that of the fast‐twitch and slow tonic fibers. These correlative analyses suggest that the avian muscles contain not only the fast‐twitch and slow tonic fibers previously known, but also a slow‐twitch fiber that appears to be intermediate between the tonic and the mammalian slow‐twitch fiber type. Based on the abundance of the sarcotubular system, this fiber type appears to be fast‐contracting and ‐relaxing, in spi

ISSN:0003-276X    

DOI:10.1002/ar.1092180206

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe distribution of fiber types in selected leg and thigh muscles of three male Cynomolgus monkeys were determined. Almost all fibers could be classified as fast‐glycolytic (FG), fast‐oxidative glycolytic (FOG), or slow‐oxidative (SO) according to the qualitative histochemical staining scheme described by Peter et al. (1972). Most muscles showed regional variations in fiber‐type distributions, i.e., the percent SO was higher and the percent FG was lower in the deep, compared to the superficial, regions of the muscle. Exceptions were the soleus and plantaris muscles, which contained similar distributions of fiber types throughout their cross sections. In the extensor compartment of the leg, a layering of fiber types from deep to superficial were evident in the triceps surae and plantaris complex with the deepest muscle, the soleus, having primarily SO fibers. A similar layering arrangement was observed in the extensor compartment of the thigh, with the deepest muscle, the vastus intermedius, having a much larger proportion of SO fibers than the other muscles in the quadriceps complex. These results indicate that Cynomolgus monkey hindlimb muscles, unlike human leg muscles (Saltin and Gollnick: Handbook of Physiology, L.D. Peachey, ed. American Physiological Society, MD, pp. 55–631, 1983) have a regional distribution of fiber types similar to that observed in many subprimate mammals. Further, the presence of compartmentalization of fiber types within the cross section of several of the muscles studied is suggestive of structure‐function interrelationships related to mo

ISSN:0003-276X    

DOI:10.1002/ar.1092180207

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

年代:1987

数据来源: WILEY

摘要:

AbstractArticular cartilage is known to have limited ability to heal once injured, and attempts to heal lesions in cartilage have yielded equivocal results. The following experiments were performed to investigate healing in cartilage following transplantation of chondrocytes grown in vitro. The knee joint of the New Zealand White rabbit was used as the experimental model. An initial baseline study was made to determine the intrinsic capability of cartilage for healing defects that do not fracture the subchondral plate. A second experiment examined the effects of autologous in vitro grown chondrocytes on the healing rates of these defects. The results were evaluated by qualitative and quantitative light microscopy.In control defects not grafted with chondrocytes, 6 weeks after the initial defect was created, there was little repair. Macroscopic and histological findings were consistent with an osteoarthritic pathology such as synovitis and “cell nests.”Macroscopic results from grafted specimens displayed a marked decrease in synovitis and other degenerative changes. Defects which had received transplants had a significant amount of cartilage reconstituted (82%) compared to ungrafted controls (18%). Controls showed a healing rate comparable to that obtained in the initial baseline st

ISSN:0003-276X    

DOI:10.1002/ar.1092180208

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

年代:1987

数据来源: WILEY

摘要:

AbstractA light and electron microscope study of the small intestine of the little brown bat,Myotis lucifugus, was carried out at several stages in the animal's annual life cycle. An unusual morphological observation was the presence of cells in the lamina propria of the small intestine which were packed with a conspicuous basophilic granular material that appeared crystalline. Moreover, such cells were present only during the hibernation period and were therefore called “hibernation crystalloid” (HC) cells. By light microscopy, the crystal‐like material was not sudanophilic, did not stain for nucleic acids, and did not contain acid phosphatase; it did show reactivity when stained by the periodic acid–Schiff procedure. By electron microscopy, the crystal‐like material was found to be present in smooth, membrane‐enclosed vacuoles along with an amorphous, dense granular substance. The crystal‐line material occasionally formed rigid‐appearing rods that reached lengths of 10 μm. The crystal‐containing cells were contacted by axonal varicosities. It is suggested that these innervated HC cells represent a unique cell type with a gastrointestinal function, yet to be determined, that may be rela

ISSN:0003-276X    

DOI:10.1002/ar.1092180209

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe cardiac atria are known to play a role in blood volume homeostasis, secreting a peptide that induces a potent natriuresis and diuresis. This peptide is atrial natriuretic factor (ANF), and its primary site of storage is within atria‐specific granules found in atrial cardiocytes.Since salt loading results in an increase in circulating levels of ANF, our aim was to determine if the atria‐specific granule population in the cardiocytes of Dahl rats would decrease accordingly. To this end, the fractional volume of the atria‐specific granules was determined by ultrastructural morphometric analysis in the Dahl salt model of hypertension. This analysis was performed on the right atria of Dahl salt‐resistant (DR) and salt‐sensitive (DS) rats fed either a low‐salt (0.4%) or high‐salt (8%) diet for 12 weeks prior to sacrifice. DR and DS rats fed a low‐salt diet had significantly reduced plasma sodium levels and osmolalities, and a significantly lower mean arterial blood pressure than did rats fed a high‐salt diet. The fractional volume of atria‐specific granules was significantly lower in salt‐loaded DR (P<0.01) and DS (P<0.025) rats than in their respective low‐salt controls. This significant decrease in atrial granules corresponds to the reported decrease in the storage of atrial ANF in salt‐loaded rats, and provides a morphological verification of the biochemical studies. Moreover, these results, in combination with a growing body of physiological data, lend support to the hypothesized role of ANF in the regulation of water–electrolyte balance, which may play an important role in cardiovascular pathophysiological sta

ISSN:0003-276X    

DOI:10.1002/ar.1092180210

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

年代:1987

数据来源: WILEY

摘要:

AbstractTritiated thymidine accumulated in pial surface structures 1–10 days after interruption of the right middle cerebral artery (MCA) in the rat. Essentially no radioactive marker was present in the underlying cortical territory of the interrupted MCA other than at the operation site. Control meninges, cortex contralateral to the operated MCA, and structures proximal to the operation site were without appreciable accumulation of3H‐thymidine. Thus, the marked cellular proliferative response to MCA interruption was localized to structures of the pia‐arachnoid overlying the cortical territory of the interrupted MCA. The data suggest that after MCA occlusion a cellular proliferative response contributes to the expansion of preexisting pial surface collateral vessels and that the expansion does not extend into the paren

ISSN:0003-276X    

DOI:10.1002/ar.1092180211

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

年代:1987

数据来源: WILEY