摘要:

AbstractPopulations of “synaptic” ribbons (SR) in pinealocytes of the rat pineal gland at various ages from the neonatal period through early adulthood were analyzed morphometrically. Diurnal and nocturnal numbers of SR were small on day one but had increased dramatically by the end of the first week and beginning of the second week. By day 10, numbers of SR had peaked. Thereafter nocturnal numbers of SR demonstrated no significant increases or decreases. However, between days 10 and 19, diurnal numbers of SR decreased precipitously, appearing to have leveled off at the onset of puberty to levels observed in adults. SR were never scarce or absent in any age group studied.The neonatal appearance of large numbers of SR coincides developmentally with the initial sympathetic innervation of pineal parenchyma. Circadian rhythm in numbers of SR begins shortly thereafter. It is suggested (1) that circadian rhythm in numbers of SR is initiated and regulated or modified by sympathetic innervation of pinealocytes containing SR, and (2) that SR formation may be related to the intracellular flow of membrane relative to the transport and release of specific pineal produ

ISSN:0002-9106    

DOI:10.1002/aja.1001570403

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

年代:1980

数据来源: WILEY

摘要:

AbstractTo identify intracellular calcium pools that may be involved in the secretory process in prolactin (PRL) cells, hemi pituitaries were incubated in medium containing 10−6M dopamine, 5 mM cyclic cAMP (experimentals), or in medium alone (controls) and then processed for electron microscopy using potassium pyroantimonate to localize intracellular calcium. PRL in the medium was measured by radioimmunoassay. The concentration of antimonate associated with mitochondria, Golgi saccules, and secretory granules was estimated. Dopamine inhibition of PRL secretion (>80% at 1, 2, 3 h) resulted in accumulation of secretory granules in all stages of maturation and dilation of Golgi saccules at 2 and 3 h, accompanied by increased mitochondrial antimonate and increased Golgi‐associated antimonate. Cyclic AMP stimulation of secretion (635% at 5 min., declining to 34% at 1 h) resulted in marked exocytosis at 5 and 15 min., declining after 30 min. Mitochondrial antimonate decreased after 30 min. Stimulated cells exhibited numerous coated membrane structures at or near exocytotic pits and an amassing of microvesicles at the margin of the Golgi apparatus. Although some secretory granules consistently exhibited reactivity to antimonate (unchanged by inhibition or stimulation), plasma membrane, and granule membrane translocated to the plasma membrane during exocytosis, were not react

ISSN:0002-9106    

DOI:10.1002/aja.1001570404

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

年代:1980

数据来源: WILEY

摘要:

AbstractGlutaraldehyde‐fixed testes were impregnated with the Ur‐Pb‐Cu technique of Thiéry and Rambourg (′76) or postfixed in ferrocyanide‐reduced osmium (Karnovsky, ′71). Thin and thick (0.5 μm) sections were examined with a Philips 400 electron microscope at 80 or 100 kv. Stereopairs were prepared from pictures of the same field after tilting the specimen every 6° from the −45 degree to the +45 degree position of EM goniometric stage. The cortex of the compact hemispherical Golgi apparatus of young spermatids (steps 2–8) was found to be composed of saccular and intersaccular regions similar to those described in the Golgi apparatus of Sertoli cells (Rambourg et al., 1979). In the saccular region, the stacks were composed of three to nine parallel saccules perforated with pores of various dimensions. On the mature or trans‐face of the stack, one or two membranous elements with a wider lumen were either closely applied to the overlying saccules or were separated from them and intermixed with the vesicular components of the medulla. On the forming or cis‐face of the stack, three or four saccules were frequently interrupted by gaps in register from one saccule to another. In three dimensions, these gaps appeared as pan‐shaped spaces or “wells,” often containing a few vesicles. Immediately overlying the first saccule on the cis‐face, a regular network of anastomotic tubules was present, corresponding to the cis‐osmiophilic element observed in other cell types. In the intersaccular region, membranous tubules connected to the edges of the saccules branched, intertwined, anastomosed, and bridged adjacent stacks of saccules. Such membranous tubules bridged saccules with the cis‐osmiophilic element or saccules of the same stack. Between the ER cisternae capping the surface of the Golgi apparatus and the cis‐network of anastomotic tubules, there was a space called the peripheral Golgi region containing small vesicles and membranous tortuous tubules. The vesicles were frequently arranged in clusters that were capped by an ER cisterna and displayed a size gradient from the periphery to the center of the cluster. Thus, although there were similarities between the three‐dimensional architectures of the Golgi apparatus in Sertoli cells and young spermatids (e.g., saccular and intersaccular regions), several structural features disting

ISSN:0002-9106    

DOI:10.1002/aja.1001570405

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe permeability of the normal muscle spindle capsule to the entrance of an exogenous protein tracer was assessed by the use of horseradish peroxidase (HRP). Adult mice were injected intravenously with a solution of HRP (MW 40,000). After varying intervals, ranging from two to 240 minutes, animals were perfused aortically with fixative, and anterior tibialis muscles were removed, processed, and examined. The results were evaluated by electron microscopic cytochemical techniques, and attention was directed to the movement of tracer and its relationship to the outer and inner capsule of the muscle spindle.HRP was first demonstrated in cytoplasmic vesicles crossing the continuous capillary endothelium supplying the muscle spindle, and was then detected in the interstitial space surrounding the outer capsule. In polar regions, HRP had entered the periaxial space by two minutes, and it was seen in cytoplasmic vesicles of the attenuated outer capsule. Later, HRP abutted the sarcolemma of intrafusal fibers, and by 12.5 minutes there was evidence of tracer in T‐tubules of these muscle cells. Whereas at no time was tracer observed traversing any of the numerous intercellular junctions of the capsule, it appeared that polar regions were leaky and open‐ended at their distal portions.The sensory equatorial zone was considerably less permeable to the entrance of tracer. Whereas HRP was visible initially in cytoplasmic vesicles of the subjacent capillary endothelium, it was not until 12.5 minutes that tracer could be demonstrated within some vesicles of equatorial outer capsule cells. At later times, a small amount of HRP was observed in the equatorial periaxial space, where it was phagocytosed and finally sequestered by cells of the inner capsule as membrane‐bound lysosomal deposits. Consequently, at no time was tracer incorporated into either intrafusal fibers or their sensory nerve terminals.Thus, in contrast to polar regions, the muscle spindle capsule in the equatorial zone appears to be effective in preventing the indiscriminate penetration of HRP from the bloodstream. This suggests dissimilar paths of tracer movement from the microvasculature into sensory and non‐sensory regions of the muscle

ISSN:0002-9106    

DOI:10.1002/aja.1001570406

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe interosseous, lumbrical, and extensor digitorum communis muscles of the human hand constitute a complex apparatus that acts to move and stabilize the fingers during grasping and manipulation. A telemetered electromyographic study of these muscles in chimpanzees was undertaken to determine whether use of the hand in locomotion and to maintain postures might be associated with functional roles different from those in humans. The manual interossei of chimpanzees are recruited in metacarpophalangeal flexion and in rapid interphalangeal joint extension. Slow digital extension can be accomplished solely by the extensor digitorum communis and lumbricals. The highly variable activity of the interossei during knuckle‐walking is compatible with their roles as ab/adductors and rotators, but such movements could not be accurately assessed. It is concluded that the generalized suspensory and specialized terrestrial locomotion of the chimpanzee is not associated with major changes in the function of the manual interossei and lumbrical

ISSN:0002-9106    

DOI:10.1002/aja.1001570407

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

年代:1980

数据来源: WILEY

摘要:

AbstractFixed vomeronasal and olfactory epithelia from normal adult garter snakes were microdissected, fractured, and examined with a scanning electron microscope. The method permits a detailed comparative study of the structural organization and morphological characteristics of the constituent cells of the vomeronasal and olfactory epithelia. Despite similarities in the nomenclature of the constituent cells in both epithelia, significant differences exist in their surface morphology. A unique columnar structure composed of non‐neuronal elements is present in the vomeronasal epithelium. These columns house the bipolar neurons and undifferentiated cells. Such a columnar organization is absent in the olfactory epithelium. In the vomeronasal epithelium the bipolar neurons possess microvillous terminals at their dendritic tips, while the dendritic tips of the bipolar neurons of the olfactory epithelium possess cilia. Vomeronasal supporting cells are covered with microvilli, while olfactory supporting cells are covered with cytoplasmic protuberances in addition to the microvilli. In the vomeronasal epithelium the pear‐shaped neurons have a grossly smooth surface and are organized into clusters, while in the olfactory epithelium the elliptical bipolar neurons are spinous, aligned side‐by‐side and interdigitate. The basal (undifferentiated) cell layer in the vomeronasal epithelium has a high packing density and is composed of several layers of irregularly shaped cells. In the olfactory epithelium the basal cell layer is loosely organized and composed of a single layer of oval cells. This information on the three‐dimensional cell structure of both epithelia provides a basis for experimental observations on changes in morphology of the bipolar neurons during genesis, development, maturation, degeneration, and regeneration in postnatal, adul

ISSN:0002-9106    

DOI:10.1002/aja.1001570408

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

年代:1980

数据来源: WILEY

摘要:

AbstractAge‐dependent changes in splenic megakaryocytopoiesis of Wistar rats, 1 hour to 60 days old, were investigated using autoradiograms of semithin sections. The highest values for3H‐thymidine labeling and mitotic indices were observed immediately after birth, whereas the maximal concentration of megakaryocytes was seen on the 14th day after birth. The transit time of megakaryocytes in newly born rats was 34.5 hours and, thus, much shorter than in adult anim

ISSN:0002-9106    

DOI:10.1002/aja.1001570409

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

年代:1980

数据来源: WILEY

摘要:

AbstractAdult male albino rats were assigned randomly to control (CON) and weight‐lifting (WL) groups. The WL rats were subjected to a progressive weight‐lifting program against high resistance for 8 weeks. During the last 2 weeks, each WL rat lifted a load equal to 130% of its body weight. The mean weight of the adductor longus muscle was significantly increased in the WL group (p<0.05). This increased muscle weight was shown to be due to an increase in the number of fibers per unit cross‐sectional area (p<0.05), and the mean sizes of both fast‐twitch oxidative glycolytic and slow‐twitch oxidative fibers were significantly smaller in the WL rats than in the CON rats (p<0.05). Light and electron microscopic examination showed that five out of eight WL rats exhibited longitudinally split muscle fibers, while only one CON rat had a few centrally placed nuclei. The splitting process appeared as either a “pinching‐off” of a small segment from the parent fiber or an invagination of the sarcolemma deep into the muscle fiber in a plane parallel to the sarcomeres. There were preliminary indications that this work‐induced fiber‐splitting process may be a physiological adaptation of muscle to the

ISSN:0002-9106    

DOI:10.1002/aja.1001570410

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

年代:1980

数据来源: WILEY

摘要:

AbstractHuman fetuses, 11.5 to 16.8 weeks' gestational age, were perfused with silicone rubber compound to study the hypothalamo‐hypophyseal portal system. Impregnated vessels were observed throughout the median eminence, infundibular stalk, pars tuberalis and both lobes of the pituitary gland in all specimens. The data suggest that an intact portal system for the transport of hypothalamic releasing factors to the pituitary gland is established as early as 11.5 weeks' gestatio

ISSN:0002-9106    

DOI:10.1002/aja.1001570411

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe PAP method was applied to adrenomedullary cells to demonstrate the subcellular localization of ELI. The labeled cell‐groups were identified from flat‐embedded virbratome sections by light microscopy. Electron microscopy showed that the precipitate was associated with the storage granules of the cells. The number of labeled granules varied greatly from cell to cell. In cells corresponding to those showing heavy staining by light microscopy, all the granules were stained with precipitate. It is suggested that the peptide responsible for the ELI might be released together with the catecholami

ISSN:0002-9106    

DOI:10.1002/aja.1001570412

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

年代:1980

数据来源: WILEY