摘要:

AbstractDevelopment of intrafusal and extrafusal fibers in the soleus and medial gastrocnemius muscles in kittens was studied in sections stained by van Gieson or histochemical procedures. Cross‐sectional areas of intrafusal and extrafusal fibers overlapped extensively in the two weeks following birth, with the means for intrafusal fibers in the medial gastrocnemius muscle being larger than those for the extrafusal fibers. A definite increase in extrafusal fiber size was seen at 20 days and in intrafusal fibers at 29 days. In the one mother cat studied, mean areas for soleus and medial gastrocnemius fibers were 12 and 59 times larger than those for a kitten sacrificed the day after birth, while the intrafusal fiber areas were 3.0 and 4.8 times greater. The equatorial region in nuclear bag fibers showed no significant growth in cross‐sectional area, but almost doubled in length. In a newborn kitten, all extrafusal fibers in the soleus and medial gastrocnemius demonstrated a high level of nicotinamide adenine dinucleotide diaphorase activity, but with the adenosine triphosphatase reaction, fibers had either low or high activity. After one month, soleus fibers with high adenosine triphosphatase activity were scarce, whereas in the medial gastrocnemius fibers with both low and high levels of activity were present. The intrafusal fibers at birth were already morphologically and histochemically differentiated into nuclear chain and bag fibers, and two varieties of the latter could be recognized in slides treated for adenosine triphosphatase activ

ISSN:0002-9106    

DOI:10.1002/aja.1001410202

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

年代:1974

数据来源: WILEY

摘要:

AbstractUltrastructural changes that occur in follicular cells of the bat thyroid gland just prior to, and immediately after arousal from hibernation are discussed in relation to the known changes which occur in thyroid function during arousal from hibernation. The most distinctive ultrastructural change that takes place just before emergence from hibernation is the occurrence, extracellularly, of concentrations of small vesicles lying in the colloid near the cell's apical plasma membrane. Similar accumulations of vesicles are absent in the apical cytoplasm of the follicular cell. Other principal changes from the early hibernating state found at this time are an increase in the number of apical vacuoles, dense granules and multivesicular bodies. These changes are followed at arousal itself by the appearance of large numbers of intracytoplasmic colloid droplets, often intimately associated with dense granules. An unusual feature of these follicular cells is that although they are rich in colloid droplets, apical pseudopods cannot be found.

ISSN:0002-9106    

DOI:10.1002/aja.1001410203

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

年代:1974

数据来源: WILEY

摘要:

AbstractTo determine if the penis of the rat is supplied by long or short adrenergic neurons, hypogastric and perivascular neurectomies were performed. Reserpine, a drug which depletes the store of norepinephrine from long adrenergic nerves more rapidly than from short adrenergic neurons, has also been used to aid in characterizing this innervation. Hypogastric neurectomy, with or without denervation of the common iliac vessels, had no effect on the density or fluorescence intensity of adrenergic fibers in the rat penis. The long adrenergic fibers to the atria did not fluoresce in reserpine‐treated rats; however, fluorescent adrenergic fibers in the penis and vas deferens remained visible. Reserpine depressed atrial levels of norepinephrine by 75%, while norepinephrine in the penis and vas deferens was reduced only by 32% and 29%, respectively. The absence of any effect of hypogastric neurectomy on the adrenergic fibers of the penis indicates that such fibers arise from neurons distal to the site of lesion of the hypogastric nerves. This result and the similar response of the vas deferens and penis to reserpine strongly suggest that the penis of the rat is supplied by short adrenergic neuron

ISSN:0002-9106    

DOI:10.1002/aja.1001410204

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

年代:1974

数据来源: WILEY

摘要:

AbstractWhen dinitrofluorobenzene (DNFB) is applied to the skin in mice, it induces a state of delayed hypersensitivity. During the three days following the application of this contact agent, lymphoblasts accumulate in the diffuse cortex of the lymph node draining the area of sensitization. This accumulation of blast cells – referred to as a blastogenic response – appears to be part of the induction phase of delayed hypersensitivity.This is an investigation into the origin of the cells of the blastogenic response. There is evidence from other studies that lymphocytes immigrate to the lymph nodes draining a site of sensitization. This paper provides complementary evidence that cellular proliferation in the diffuse cortex of the sensitized lymph node is another source for the accumulation of blast cells. This proliferation has been studied by counting mitotic figures, and by autoradiography after giving3H‐thymidine in order to determine the number of blast cells undergoing DNA synthesis and the duration of the various phases of the cellular reproductive cycle.The results show a high degree of correlation between mitotic figures and blast cells in the diffuse cortex of the sensitized lymph nodes, consistent with a population of dividing blast cells. Approximately 80 percent of the blast cells were in the DNA‐synthetic phase of the reproductive cycle at the peak of the blastogenic response, and the cells were dividing with approximately an eight hour generation time.These results can be interpreted to indicate that the cells of the blastogenic response, although accumulating initially by immigration to the draining lymph node, become a homogeneous, nondifferentiating population of blast cells, all proliferating at near maximal rate to provide the great numbers of blast cells seen three days after application of the sensitizin

ISSN:0002-9106    

DOI:10.1002/aja.1001410205

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

年代:1974

数据来源: WILEY

摘要:

AbstractFifty‐one temporomandibular joints (24 male, 27 female) obtained at autopsy were used in the study. Forty‐four specimens were younger than ten years while others ranged to 21 years. These joints were radiographed, sectioned sagittally or frontally, and slide‐mounted as decalcified and undecalcified sections using conventional histologic techniques. The slides were examined microscopically in whole, polarized, and ultraviolet light. Two of the specimens surveyed exhibited fluorescent labeling as a consequence of therapeutic tetra cycline application.Throughout the postnatal developmental period the articular tissue and disc consist of fibrous connective tissue. Cartilage cells were not observed in these structures at any time during the twenty‐one year age‐span studied. At birth the disc is flat and develops an accentuated S‐shaped profile as the articular tubercle develops.The articular tubercle is only a small elevation at birth and is formed by a combination of endochondral, immature, and ordinary intramembranous bone formation. The characteristic profile of the temporal portion of the joint is achieved during the first two or three years of life, after which gradual enlargement and compaction of bony structures occur.While the mandibular condyle grows in a constant posterior, superior, and lateral direction, it does not attain its mature contour until the late mixed dentition age. Condylar growth cartilage is approximately 1.5 mm thick at birth but it thins down in a short time to about 0.5 mm. During the first two years of life the growth cartilage is penetrated by vascularized connective tissue septa whose function appears to be nourishment of the cartilage. The growth cartilage does not show the columnar arrangement of chondrocytes seen in epiphyses, nor are isogenous groups observed. At 16 to 17 years, the growth cartilage becomes thinner and a closing plate of bone is beginning to coales

ISSN:0002-9106    

DOI:10.1002/aja.1001410206

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

年代:1974

数据来源: WILEY

摘要:

AbstractMapping of the peripheral specialized conducting system of the heart could contribute to an understanding of normal and abnormal impulse propagation. In this study, a sheep right anterior papillary muscle was sectioned serially and stained for Purkinje fibers with the periodic acid Schiff and hematoxylin procedure. The subendocardial Purkinje fibers entered the papillary muscle through its base and extended nearly to its apex. Except for one “mixed” fiber group, the subendocardial fibers did not connect to the deep Purkinje fibers, and both groups contained discontinuous Purkinje fibers. The fibers of the moderator band radiated in such a complex fashion that they could not be reconstructed exactly, but they generally disappeared in the ventricular wall through the base of the papillary muscle and false tendons. No direct connections between the subendocardial Purkinje fibers and those of the moderator band could be found within the boundaries of the papillary muscle, and this may form the basis for the relatively late activation of the papillary muscle as compared to the surrounding myocardial wall. The discontinuous fibers we observed are compatible with a current concept regarding the embryology of the ventricular specialized conducting system, and are not in conflict with normal impulse propagat

ISSN:0002-9106    

DOI:10.1002/aja.1001410207

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe chorioallantoic placenta from six crabeater seals (Lobodon carcinophagus) with fetuses from 15–180 mm crown rump length (CRL), and two leopard seals (Hydrurga leptonyx) with fetuses 76 and 86 mm CRL was lobulated, zonary, labyrinthine and endotheliochorial. The fine structure of the placenta was essentially similar in both species. Maternal capillaries of the labyrinth had attenuated endothelial cells unlike the fissiped carnivores. They were surrounded by an outer syncytiotrophoblast, incomplete inner cytotrophoblast, and a core of mesenchymal tissue containing fetal vessels. In general, the cytotrophoblastic cells were less electron‐opaque than the syncytium; the former possessed abundant free ribosomes, while the latter had many nuclei, mitochondria, and numerous strands of rough endoplasmic reticulum. Mitotic figures were observed only in the cytotrophoblast. Plasma membranes between the trophoblastic layers had interdigitating processes which showed many desmosomes along the intercellular spaces, whereas membranes surrounding the maternal capillaries were usually smooth. In the limb‐bud stage embryo, the syncytiotrophoblast had thick and thin areas which became progressively attenuated in older fetuses. Instances of intratrophoblastic fetal capillaries were observed in seals with fetuses of 40 mm CRL and older, with consequent greatly thinned placental barriers. By Perl's reactions, Turnbull's method, and electron microscopy, rows of granular bodies positive for iron were demonstrated along the basement membrane of the trophoblastic cells and in the mesenchymal cells of the crabeater seals, but not the leopard seals. Furthermore, it is suggested that the deposits of granular bodies show the sites of iron storage in the placentas. In the limb‐bud stage embryo the hematome borders and isolated pouches of the central hematome were observed. The central hematome was antimesometrial. The hematomes were lined by columnar cytotrophoblastic cells which phagocytized extravasated maternal blood and absorbed histiotrophic m

ISSN:0002-9106    

DOI:10.1002/aja.1001410208

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

年代:1974

数据来源: WILEY

摘要:

AbstractThis study is concerned with the passage of carbon particles through the sinusoidal lining cells of bone marrow and embryonic liver of the rat. A carbon suspension (Pelikan C11/1431A, Günther Wagner, Hanover) diluted 1:1 with double strength Tyrode solution, was administered through the aorta for the bone marrow studies and through the umbilical vein for observations on the embryonic liver. The carbon particles have a diameter ranging from 220 to 380 Å with a mean diameter of 280 Å. Within three minutes after the injection, the particulate was present in the extravascular spaces. Neither the sinusoidal walls of the bone marrow nor of the embryonic rat liver prior to 16 days gestation have preformed apertures. In both cases, the carbon particles enter the extravascular space through fenestrae with diaphragms. No carbon particles occur in the junctional spaces between the lining cells. The temporary pores caused by diapedetic blood cells maintain a tight seal and no particulate was observed leaving the vascular space at these sites. At 17 days of gestation, open gaps develop in the endothelial lining of the embryonic rat liver and particulate material leaves the vascular lumen through these openings. The presence of bristle‐coated vesicles containing particulate material at the abluminal side of the lining cells is interpreted as a retrograde uptake by these phagocytic cells rather than as evidence for vesicular transmural trans

ISSN:0002-9106    

DOI:10.1002/aja.1001410209

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

年代:1974

数据来源: WILEY

摘要:

AbstractCytochalasin‐B (CB) induces cells to contract. This contraction is biphasic. The rapid response peaks in 30 minutes and is followed by a slower contraction that leads to the “arborized” configuration. If fully arborized cells are removed from CB and exposed to colcimide they are induced to form twisting, birefringent bands. These bands consist of massive numbers of 100 Å fil

ISSN:0002-9106    

DOI:10.1002/aja.1001410210

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

年代:1974

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001410211

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

年代:1974

数据来源: WILEY