摘要:

AbstractThe morphological features of avian epiphyseal cartilage have been investigated by freeze‐fracture techniques. Progressive changes occurred in both the cells and the matrix during differentiation. Chondrocytes changed in shape from small flattened cells with few, short cellular processes, to enlarged ovoid cells with numerous long processes often associated with extracellular vesicles. In the matrix these vesicles appeared first in the cellular lacunae, then in the extralacunar matrix, becoming larger and more numerous. Large membrane‐associated particles (MAPS) were seen on thepfaces of the plasmalemma. These became progressively concentrated on and around the cellular processes, with few large MAPS being seen on theeface. Similar distribution of MAPS was seen in the matrix vesicles. Domains of hydrated proteoglycan aggregates were manifest as regular fracture patterns in the extralacunar matrix of the upper regions of the plate. Collagen fibrils progressively increased in size and state of aggregation, often being associated with matrix vesicles and in the end, with long plate‐like mineral crystals. These findings, while in basic agreement with patterns observed with TEM, reveal important new features concerning cellular and matrix structure during cartilage differenti

ISSN:0003-276X    

DOI:10.1002/ar.1091990402

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

年代:1981

数据来源: WILEY

摘要:

AbstractFibroblasts of the periodontal ligament (PDL) of the mouse exhibit a high degree of cytoplasmic and functional polarity. This polarity is dependent upon an elaborate system of microtubules. The location of the microtubular arrays and the observed effects of colchicine administration suggest that microtubules play an important role in maintaining the organization of the Golgi complex and its functional relationship to the rough endoplasmic reticulum. Smooth‐walled intermediate vesicles, apparently derived from the rough endoplasmic reticulum, are aligned along microtubules at the immature face of the Golgi apparatus, and mature secretory granules are closely related to microtubules at the mature face of the Golgi apparatus. In distal cell processes the granules are closely parallel to microtubules and on occasion bridge‐like attachments from granules to microtubules were noted. This relationship of secretory granules to microtubules, the lack of granule storage, and the effects of colchicine on granule secretion suggests that microtubules are part of a mechanism for collagen granule translocation from the Golgi complex to the cell periph

ISSN:0003-276X    

DOI:10.1002/ar.1091990403

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to assess the importance of the phagocytic mechanism of collagen resorption in the normal turnover and remodelling of soft connective tissues. Collagen phagocytosis by fibroblasts in rat skin, attached gingiva, and periodontal ligament was quantitated using the methodology of electron microscopic stereology. Periodontal ligament contained five and 15 times as much phagocytosed collagen as attached gingiva and skin respectively. Also, for each tissue examined, a positive correlation was observed between the amount of collagen phagocytosed and the known rate of mature collagen turnover.

ISSN:0003-276X    

DOI:10.1002/ar.1091990404

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe present study defined the ultrastructural features of peritubular capillary development. Two‐day‐old beagle puppies and adult dogs were perfused with 2.5% glutaraldehyde and routinely prepared for light and transmission electron microscopy. Some of the fixed tissue was subsequently used to make freeze‐fracture replicas.The outer cortex of the puppy kidney possessed large, thick‐walled vessels best termed sinusoidal capillaries instead of the small caliber vessels (peritubular capillaries) noted in the adult. These sinusoidal vessels showed extensive overlapping of the endothelium with isolated patches of fenestrae. Their luminal surfaces were irregular, owing to prominent ridges and sporadic bulges of endothelium. The basement membrane of most vessels was not present. Interstitial spaces were filled with mesenchymal cells and cells closely resembling pericytes. The diameter of the fenestrae of vessels throughout the cortex was similar; however, the number of fenestrae per micrometer of endothelium increased significantly from outer to inner cortex. Vessels of the inner cortex were also immature when compared to the adult. From these morphological findings, it was apparent that a true peritubular capillary system does not exist in the two‐day‐old puppy. Ultrastructural features of these vessels suggested reduced permeability char

ISSN:0003-276X    

DOI:10.1002/ar.1091990405

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

年代:1981

数据来源: WILEY

摘要:

AbstractA study of the circadian rhythm in the mitotic index (MI) of the corneal epithelium was completed in non‐tumor‐bearing mice and in mice bearing the Ehrlich ascites carcinoma (EAC). All mice were standardized to a light‐dark cycle with 12 hours of light from 0600 to 1800 CST alternating with 12 hours of darkness from 1800 to 0600 CST. Treatments included injection with saline (SAL) or hydroxyurea (HU) at different circadian times. This investigation demonstrated that: (1) Data from untouched animals cannot serve as proper controls because treatment with SAL altered the level of the MI, but only during the diurnal, not the nocturnal, phase of the circadian cycle; (2) the presence of the EAC depressed the level of the MI, but this inhibition was only detected during the diurnal period; (3) treatment with 500 mg/kg HU injected at 0500 caused more perturbation in this rhythm than did treatment with 500 mg/kg HU at 1700; (4) when 500 mg/kg HU was given at 2000 and 0100 and 0500, the perturbation of the rhythm was greater than when 500 mg/kg HU was given at 0900 and 1400 and 1700; (5) when 3000 mg/kg HU was given at 1700 and compared to 500 mg/kg HU at 1700, little difference in the overall circadian profiles of these rhythms was observed, indicating that the circadian control mechanisms operating on the MI exerted a greater influence than did a dosage change from 500 to 3000 mg/kg HU; and (6) a comparison of the practice of plotting experimental and control data as “hours after treatment” versus using a “time of day” plot for the same data demonstrated that the “hours after treatment” plot is very misleading because it fails to account for the significant circadian oscillation in

ISSN:0003-276X    

DOI:10.1002/ar.1091990406

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

年代:1981

数据来源: WILEY

摘要:

AbstractTwo mice with an XXY karyotype and cryptorchid testes appeared spontaneously in a colony. The animals were H‐Y antigen‐positive, and had elevated serum levels of follicle‐stimulating (FSH) and luteinizing (LH) hormones. Testes of the affected mice were atrophic, containing a few solid seminiferous cords surrounded by vast amounts of compact interstitial material. The cords were delimited by a broad tunica propria in which the basal lamina was irregularly thickened and stratified into a number of alternating dense and less dense layers. Most sex cords were populated by mature Sertoli cells and small pleomorphic elements resembling monocytic‐derived macrophages. Within some cords, the macrophages aggregated into a central mass with which identifiable Sertoli cells and (PAS) periodic acid Schiff‐positive fragments of basal lamina were associated. In more severely damaged cords, the basal lamina and peripheral carpet of Sertoli cells were totally missing. Such cords were populated only by the central macrophages with fragments of basal lamina and degenerating Sertoli cells. Finally, a few collapsed remnants of cords contained compact nodules of macrophages surrounded by what appeared to be the outer part of the tunica propria. The interstitial area, as well as the outer walls of the seminiferous cords were also heavily infiltrated by macrophages. Overall, the morphological picture was one of severe immunological injury. We do not know what role, if any, the genetic constitution and/or intra‐abdominal environment may play in the expression of these bizarre pathologies. However, such severe changes have not been reported in either Klinefelter's syndrome or the undescended testes of any human or subprim

ISSN:0003-276X    

DOI:10.1002/ar.1091990407

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe Weddell seal cow possesses two subcutaneous, ellipsoidal, abdominal mammary glands with a volume of two to three liters when lactating. Corrosion casts reveal that approximately ten large ducts radiate from a gland cistern at the base of the nipple, and end in a complex system of terminal branches. Each gland has a separate arterial supply, mostly from the caudal deep epigastric with a minor contribution from the deep circumflex iliac. Histologically, lactating, nonlactating (resting), and immature glands resemble those of other eutherians. Sinusoidal blood vessels, not observed in the mammary glands of other mammals, are present within lactating but not in resting lobules in the seal. The terminal pouch and lactiferous sinuses possess circular smooth muscle and elastic fibers in the walls, and accumulations of lymphocytes immediately beneath the epithelium. Sebaceous and sweat glands open into the walls of the nipple and the apex of the terminal pouch. There are extensive networks of blood vessels and longitudinal smooth muscle and elastic fibers in the walls and base of the nipple. The possible functions of these morphological observations are discussed.

ISSN:0003-276X    

DOI:10.1002/ar.1091990408

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

年代:1981

数据来源: WILEY

摘要:

AbstractFluorescence microscopy of thymus and spleen from four strains of mice (C3H and ICR controls, AKR spontaneously leukemic and NZB autoimmune) revealed varicose noradrenergic (NE) fibers in perivascular and parenchymal regions of both organs. Thymic innervation was largely perivascular, but isolated islands and strings of free NE fibers were noted among thymic parenchymal cells. A morphological proximity between NE fibers in the thymus and mast cells was noted in all strains studied, but was exceptionally prominent in the NZB thymus. Perivascular plexuses within the splenic white pulp sent single NE fibers between the surrounding lymphocytes. Catecholamines and histamine have been shown to modulate lymphocyte development and activity in vitro. The present study provides morphological evidence that both NE and histamine are available to lymphocytes in thymus and spleen, and thus provides morphological evidence for neurla modulation of immune activity in vivo.

ISSN:0003-276X    

DOI:10.1002/ar.1091990409

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the albino rat embryo pineal gland was studied from day 13 of development through birth. In the first stages (13–16.5 days of development) the pineal evagination presents a barely differentiated epithelium. From 17 days onward the transformation of the pineal gland from a tubular evagination into a compact organ occurs. The obliteration of the recess takes place by means of two mechanisms: (a) multiple foldings of the epithelium which determine an approximation and fusion of the walls of the recess, and (b) occupation of the lumen by cells extruded from the pineal epithelium. Embryos of 18–21 days of gestation still show remains of the pineal recess.Frm day 16.5 onward elements of the pineal parenchyma have been found outside the pineal epithelium contour. They contact with the mesenchymal cells without a basal lamina separating both elements.Day 20 marks the beginning of recognizable differentiation of pineal cellular types. However, in the newborn rat these types are not yet clearly establis

ISSN:0003-276X    

DOI:10.1002/ar.1091990410

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

年代:1981

数据来源: WILEY

摘要:

AbstractLarval lampreys (Lampetra japonica) 13 and 21 mm in body length were examined by serial section electron microscopy and it was found that the young 13‐mm larvae which was 26 days old had no nerves to, and in, the heart. However, the heart of 21‐mm larval lampreys had two sets of nerve fibers entering the heart. One of the nerve fibers entered the heart via the porta venosa, ran along the vena jugularis impar, and ended in the sinus venosus. The other nerve entered with the porta arteriosa and terminated in the proximal region of the bulbus cordis. Two characteristic types of nerve endings were observed. One type of nerve ending contained numerous, small, clear vesicles about 40 nm in diameter. These endings were found only in the walls of the vena jugularis impar and the sinus venosus. The second type of ending characteristically contained distinctive large‐cored vesicles 60–130 nm in diameter mixed with numerous small, clear vesicles. These endings were present in the walls of the vena jugularis impar, the sinus venosus, and the bulbus cordis. It should be emphasized that the bulbus contained only the second type of nerve ending. The nerves in the heart were confined to specific regions and those from the two sources remained separate. Furthermore, the atrium, ventricle, ducts of Cuvier, and hepatic veins were completely devoid of nerves. There were no ganglion cells in any region of th

ISSN:0003-276X    

DOI:10.1002/ar.1091990411

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

年代:1981

数据来源: WILEY