摘要:

AbstractThe spatial distribution of twitch and tonic fibres in a snake muscle one myofibre thick (ventral costocutaneous) has been investigated. It was found that small groups of like fibres were favoured at the expense of larger groups when compared with sequences generated by a computer in which fibres were distributed randomly. The number of times that like fibres occurred next to one another was used as another measure of their spatial distribution. The number of adjacencies of like fibres was less than the expected number of adjacencies determined both by random sequences and by probability theory. The expected number of adjacencies determined by means of random sequences and a priori probability theory were almost identical. This dispersion of like fibres may reflect processes that occur during muscle development and may have functional implications.

ISSN:0003-276X    

DOI:10.1002/ar.1092170102

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

年代:1987

数据来源: WILEY

摘要:

AbstractA study of the isthmus and ligament in unionid mussels was undertaken employing methods specifically designed to preserve the in vivo relationships of these interrelated structures. Serial sections of the hard and soft tissues were used for two‐dimensional analysis. From these, a tridimensional computerized reconstruction was developed. Special dissections of the undisturbed isthmus were also utilized. By using such methodologies, a new description of the ligament has been developed employing such terminology as the foliated ligament and the posterior folding laminae. Similarly, for the isthmus, an anterior lyre, a pallial crest, a pallial peduncle, and a posterior lyre are described. Such entities are both morphologically and physiologically related to the shell and ligamen

ISSN:0003-276X    

DOI:10.1002/ar.1092170103

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe teeth of the filefish were investigated with light and scanning electron microscopy. Anterior and posterior rows of pleurodont teeth are present in the maxilla. The teeth in the anterior row possess a large labial and small lingual surface and the teeth in the posterior row possess a small labial and large lingual surface. The enameloid consists of three layers–the outer, middle, and inner layer. The outer layer consists of fine, parallel crystallites oriented perpendicular to the surface. They are similar to the crystallites in enamel derived from ectoderm. In the middle layer the crystallites form parallel bundles that are oriented in the same direction as that of the crystallites in the outer layer. In the inner layer bundles of crystallites interlace with each other. The tubular structures and the terminal branches of the dentinal tubules are located among the crystallites in the inner layer. In the dentine numerous dentinal tubules radiate from the pulp cavity toward the periphery and are seen to curve slightly in an S‐shaped course. At the occlusal tip the alternating parabolic layers are seen and these are considered to be mineralized lines. The openings of the dentinal tubules are round or oval, surrounded by interlacing fibrils. The teeth are tightly fixed to the jawbone by bundles of fibrils. At the lower part of the lingual surface of the teeth in the anterior row and the labial surface of the teeth in the posterior row the bundles of fibrils start at the dentine and some fibrils run through connective tissue, while others terminate in projections of the jawbones. These structures are discussed in comparison with those of other spec

ISSN:0003-276X    

DOI:10.1002/ar.1092170104

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

年代:1987

数据来源: WILEY

摘要:

AbstractEffects of pregnancy stimulation upon histochemically assessed myofibrillar ATPase and muscle fiber diameters were analysed in the rectus abdominis (RA) muscle of guinea pig. Samples of the muscle were taken at 30, 40, 50, 60, and 70 days of pregnancy and compared with samples of the same muscle taken from nonpregnant guinea pigs. Changes in muscle fiber proportions were noted through the course of pregnancy. Starting from 50 days of gestation an increase in type I fibers and a decrease in type IIB fibers were noted. Increase in muscle fiber diameters was also observed in type I, IIA, and IIB fibers. In addition, the RA muscle of the male guinea pig was compared with that of the female guinea pig and showed more type IIA and less type IIB fibers and all the three fiber types were larger than those of the female.

ISSN:0003-276X    

DOI:10.1002/ar.1092170105

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

年代:1987

数据来源: WILEY

摘要:

AbstractA qualitative and quantitative analysis of M. vastus lateralis fibers from 40 male sedentary subjects, ranging in age from 30 to 89 years, was carried out by light and electron microscopy and by an automatic Interactive Image Analysis System. Biopsies for enzyme histochemical and ultrastructural studies were taken from subjects subdivided into four age groups: 30–50, 60–70, 71–80, and 81–89 years. Attention was focused on the fiber type size and distribution, the size and the amount of mitochondria, and the amount of lipid droplets. Main changes observed in the four age groups are indicative of a sequence of events within senescent skeletal muscle fibers. With increasing age the enzyme histochemical reactions reveal changes in fiber type distribution characterized by decrease in muscle fiber diameter and by type I fiber predominance.Type II fiber atrophy is consistent. Type I fiber predominance seen in older subjects could be related to a selective decrease of type II fibers with age. It also suggests a possible conversion of type II fibers to type I fibers. Lipid droplet percentage per fiber area increases, while mitochondrial size and mitochondrial percentage per fiber area decrease with age. It is possible that energy requirements decline with age and that the decrease in mitochondrial size and percentage represents a response to a reduced metabolic

ISSN:0003-276X    

DOI:10.1002/ar.1092170106

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

年代:1987

数据来源: WILEY

摘要:

AbstractAfter fetal lungs are placed in organ culture, any macrophages arising in them must develop from precursors present at explantation. Whole pseudoglandular lungs from 20 litters of rats were set on an agar medium containing fetal bovine serum on the 14th prenatal day when the metamorphosing embryos do not yet have circulating monocytes. After a day in vitro, 10–30‐μm clusters of rounded cells began to appear in the pulmonary connective tissue. They increased in size, displayed mitotic figures, and were supplemented by additional clusters on succeeding days. Late in the second day, cells began to penetrate the visceral pleura and over the next week built up a large population outside. Histochemically, the intrapulmonary foci and emerging cells were reactive for naphthyl acetate esterase and acid phosphatase, and many were stainable for triglyceride. Within the lungs elevated acid phosphatase activity was first seen at 24 hours; it attained the level of activated alveolar macrophages 1–2 days later. After cells had been emerging 4–5 days, comparatively few clusters remained in the stroma, but some cells had crossed into the airway, to be swept along by ciliary currents. Some cultures were injected with submicronic iron oxide particles on the first day. The particles gradually concentrated within the stromal clusters, and a few emerging cells contained them. Emerged cells avidly ingested iron oxide and rhodamine‐coated latex microspheres. Cells adhering to the cultures were centers of rosette formation after exposure to sheep erythrocytes opsonized with rabbit antisheep IgG and complement factors. The explants evidently contained precursors of macrophages. Cultural conditions provoked them into dividing and exhibiting activation of lysosomes and capacity for directed migration; our experiments showed the transformed cells to be phagocytic and to have receptors associated with immune phagocytosis. The study indicates that macrophages directly derived from stem cells in embryonic lungs are similar in essentials to macrophages in adult lungs, and that this component of pulmonary immune defense is present in an occult form from almost the outset of d

ISSN:0003-276X    

DOI:10.1002/ar.1092170107

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe present work examines the ability of prolactin to enter the CNS of the rat and effect its feedback stimulation of dopamine release prior to the appearance of prolactin receptors in choroid plexus (i.e., 10 days postnatal). An inhibitor of tyrosine hydroxylase was used to allow the assessment of dopamine turnover separate from synthesis and transport of the amine. Chronic but not acute hyperprolactinemia resulted in increased dopamine release relative to vehicle‐treated controls, as shown by diminished fluorescence intensity in the median eminence. These results indicate that activation of the prolactin short‐loop feedback system occurs by 10 days postnatal, prior to the appearance of prolactin receptors at the choroid ple

ISSN:0003-276X    

DOI:10.1002/ar.1092170108

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

年代:1987

数据来源: WILEY

摘要:

AbstractRabbits were intravenously primed and boosted with trinitrophenyl‐keyhole limpet hemocyanin (TNP‐KLH) and human serum albumin (HSA); both antigens were injected simultaneously. The localization of anti‐TNP‐antibodyforming cells (AFCs) and anti‐HSA‐AFCs was determined in various lymphoid organs of the rabbit.In all lymphoid organs of primed rabbits anti‐TNP‐AFCs outnumbered anti‐HSA‐AFCs, with the exception of the thymus, in which neither of them was encountered. In the spleen the antibody‐forming cells were mainly situated in the periphery of the periarteriolar lymphocyte sheaths (PALS) and in the coaxial sheaths of lymphoid tissue surrounding the terminal arterioles. In the lymphoepithelial organs AFCs were almost exclusively situated in the interfollicular areas, and in the lymph nodes largely in the medulla.An intravenous booster injection led to a secondary immune response (i.e., increase of AFCs) in the spleen. No visible change in the number of specific AFCs was observed in the lymphoepithelial organs. However, in the mesenteric and popliteal lymph node the number of anti‐TNP‐AFCs h

ISSN:0003-276X    

DOI:10.1002/ar.1092170109

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe mechanisms whereby the normal pattern of muscles within the developing chick limb bud is generated are largely unexplored. It has been proposed that the muscle pattern is established independently of the pattern for the limb skeletal elements to which the muscles normally attach (Shellswell and Wolpert: “The Pattern of Muscle and Tendon Development in the Chick Wing.” In:Vertebrate Limb and Somite Morphogenesis. Cambridge University Press, Cambridge, pp. 71–86, 1977). To further examine this possibility we studied the formation of the proximal wing muscles in normal andwinglesschick embryos. The muscles of the shoulder region (including the pectoralis) arise as part of the dorsal and ventral premuscle masses of the developing limb bud. These secondarily migrate out of the limb to take origin from the pectoral girdle while inserting onto the humerus (Sullivan:Aust. J. Zool., 10:458–516, 1962). With rare exceptions,winglessembryos have complete absence of wing skeletal elements, but they may possess more than 40% of the normal volume of wing‐bud‐derived muscles. The muscles that remain inwinglessembryos are primarily shoulder muscles, and to a varying extent, the pectoralis. The question we sought to answer was whether inwinglessembryos the proximal wing muscles could form a normal pattern in the absence of the humerus and distal wing skeletal elements. By examining three‐dimensional reconstructions of the proximal wing region in normal andwinglessembryos, we found that the initial subdivision of the dorsal and ventral premuscle masses proceeded normally in the absence of the wing skeleton. This resulted in a grossly normal pattern of proximal wing muscles despite the absence of wing skeletal elements. However, some subsequent cleavages of individual muscles within premuscle mass divisions did not occur inwinglessembryos. This suggests that the skeleton may be required for this step in muscle morphogenesis to occur. We also observed that the wing‐budderived muscles inwinglessembryos were nearly always anchored to the pectoral girdle at both ends. Sometimes this resulted in muscles making abnormal tendonous fusions with other muscles derived from the opposite (i.e., dorsal or ventral) premuscle mass. Therefore, attachment to the skeleton may be important for some facet of muscle development. Finally, the supracoracoideus muscle was absent in all but onewinglessembryo we examined in the present study. In that one, it was substantially reduced in volume compared to normal. Despite the absence of this muscle, the space normally occupied by the supracoracoideus was maintained beneath the pectoralis. This observation suggests that the form, or shape, of a muscle may be established within the connective tissue in the absence of th

ISSN:0003-276X    

DOI:10.1002/ar.1092170110

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

年代:1987

数据来源: WILEY

摘要:

AbstractLight microscopic morphometric procedures were used in order to examine the effects of propylthiouracil (PTU) on the development of the mesencephalic nucleus of the trigeminal nerve in the duck. A single vascular injection of a 0.2% solution of PTU was administered at a dosage of 2 μl/gm embryo weight on embryonic day nine (E9). Control embryos received a similar dose of Ringer's solution. The following parameters of cytodifferentiation of cells of the mesencephalic nucleus of V were studied: somal area profiles, nuclear area, and nuclear cytoplasmic ratios. In addition, the frequency of beak clapping was recorded from E16. Significant differences were observed in somal area profiles in the experimental group at E16 and E18 and in nuclear area profiles from E16 through hatching. Beak activity in the experimental embryos was drastically reduced. It is concluded that PTU induces a retardation in the differentiation of cells of the mesencephalic nucleus of V which may lead to behavior deficits as evidenced by reduction of beak activity. These observations provide a basis for the study of interactions between thyroid hormone and specific neuronal systems in the emergence of an adaptive function

ISSN:0003-276X    

DOI:10.1002/ar.1092170111

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

年代:1987

数据来源: WILEY