摘要:

AbstractThis study examines the early hepatic biochemical and ultra‐structural responses to insulin replacement in streptozotocin‐diabetic rats and insulin withdrawal from insulin‐maintained diabetic rats. Insulin administration rapidly lowered plasma glucose and the elevated glucose‐6‐phosphatase (G‐6‐Pase) specific activity of the diabetic rats. However, hepatic glycogen did not increase until after 3 hr of insulin treatment. Hepatic ultrastructure responded to insulin replacement after the decline in glucose and G‐6‐Pase. This was seen in periportal hepatocytes as a reduction in the close association between smooth endoplasmic reticulum (SER) and glycogen particles in the diabetic animals. The treated rats showed hepatic SER restricted to the periphery of glycogen masses, as is characteristic of these cells from normal rats, in many cells by 6 hr and all cells by 18 hr. Insulin withdrawal from insulin‐treated diabetic rats elicited nearly a total reversal of the above events. Plasma insulin declined to a value half that of the normal rats by 6 hr after withdrawal; concurrently, plasma glucose rose sharply to hyperglycemic values as hepatic glycogen content dropped. Following the rise in plasma glucose and fall in glycogen content, G‐6‐Pase specific activity increased and by 16 hr reached the high values characteristic of the diabetic animal. Hepatic ultra‐structure was also changed as evidenced by an intrusion of elements of the SER into the dense glycogen masses; the result was dispersed glycogen closely associated with SER as seen in the diabetic animal. It is concluded that the hepatic response to insulin replacement in diabetic animals and diabetic onset in insulin‐withdrawn animals is rapid and oc

ISSN:0002-9106    

DOI:10.1002/aja.1001700202

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

年代:1984

数据来源: WILEY

摘要:

AbstractInvaginations of the sarcolemma that generate the transverse‐axial tubular system (TATS) of the ventricular myocardial cells have begun to develop in the mouse by the time of birth. The formation of the TATS appears to be derived from the repetitive generation of caveolae, which forms “beaded tubules”. Beaded tubules are retained in the adult, in which they frequently present a spiraled topography. Development of the TATS progresses so rapidly that complex systems are already present in the cardiac muscle cells of young mice; by 10–14 days of age, the ultrastructure is essentially identical to that of the adult. The mouse myocardial TATS is composed of anastomosed elements that are directed transversely and axially (longitudinally). Many tubules have an oblique orientation, however, and most elements of the TATS are highly pleiomorphic. In this respect the TATS of the mouse heart is relatively primitive in appearance in comparison with the more ordered TATS latticeworks typical of the ventricular cells of other mammals. Stereological analysis of the mouse TATS indicates that the volume fraction (VV) and surface density (SV) are considerably greater than previously reported (3.24% and 0.5028 μm−1, respectively). The most complex ramifications of the TATS are embodied in the subsarcolemmal caveolar system and the deeper tubulovesicular “labyrinths”, both of which can be found in early postnatal and adult ventricular cells. In atrial cells, TATS development is initiated several days later than in the ventricular cells. The TATS of adult atrial myocardial cells is less prominent than the ventricular TATS and consists largely of axial elements; the incidence of the TATS, furthermore, is more pronounced in the left than in th

ISSN:0002-9106    

DOI:10.1002/aja.1001700203

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe tridimensional structure of the Golgi apparatus of atrial muscle cells has been studied in thin and thick sections with low‐and high‐voltage electron microscopes. Cardiac tissue was inpregnated with osmium, stained to demonstrate phosphate activity (i.e., nicotinamide adenine dinucleotide phosphatase or NADPase; thiamine pyrophosphatase or TPPase; cytidine monophosphatase or CMPase) or postfixed and stained with potassium ferro‐cyanide‐reduced osmium. At low power, in thick (3–10 μm) sections, the cis‐osmiophilic element and the NADPase‐and the TPPase‐positive saccules each appeared as a continuous irregular ribbon that formed, at the two poles of the nucleus, two conical masses connected to each other by beltlike bands encircling the nucleus. At higher magnifications, the continuous Golgi apparatus showed saccular regions along its length connected by short intersaccular tubular regions. In the saccular regions, the following five superimposed elements formed a stack: (1) the cis‐osmiophilic network of anastomosed tubules; (2) a chromophobic, dilated saccule perforated with numerous pores; (3) a thin NADPase‐positive saccule showing few pores; (4) a thin TPPase‐positive saccule perforated with numerous minute pores; and (5) a CMPase‐positive trans‐element that showed saccular and tubular regions and was often partly separated from the overlying saccule. In the intersaccular tubular regions, membranous tubules connected and bridged saccules of two adjacent saccular regions. Secretory granules usually appeared in this region as dilations of the tubules connected to all elements of the Golgi stack except t

ISSN:0002-9106    

DOI:10.1002/aja.1001700204

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe present study describes a complex array of sensory nerve terminals in the human eyelid. In many respects this pattern of innervation resembles that previously described in the rhesus monkey, but in other respects it is unique to man. The most prominent nerve terminals are a complex array of lanceolate and circular Ruffini and free nerve endings that envelop the eyelashes. In addition, Merkel cells have not been conclusively identified to date in other nonhuman primate nonsinus hairs. The external root sheath collar contains Merkel cells, and dermal Merkel cells have also been identified close to the collar. The anterior cutaneous surface of the eyelid contains small vellus hairs with typical lanceolate, Ruffini, and free nerve endings resembling those of primate facial skin.Scattered Meissner and scant simple corpuscles as well as scattered free nerve endings (FNEs) can be identified on the occlusal surface of the eyelid. Intraepithelial as well as dermal FNEs were most easily identified in this region in areas lacking other corpuscular receptors. Corpuscular receptors are especially common at the occlusal/conjunctival angle.The inner or conjunctival surface of the eyelid appears to be a glandular epithelium, whereas in the rhesus monkey it is stratified squamous epithelium. This epithelium needs additional study.In summary, the present study confirms the unique sensory neural status of the human eyelid and verifies the presence of Ruffini nerve terminals by light and electron microscopy and of free nerve ending terminals at least by light microscopy, as well as a unique pattern of innervation of the human eyelash.

ISSN:0002-9106    

DOI:10.1002/aja.1001700205

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe microvasculature of the eye of the duckling was studied with microcorrosion casting, scanning electron microscopy, and stereology. Most blood to the eyeball first passes through the arterial ophthalmic rete mirabile, a complex of small arteries which intermixes with a similar complex of veins (venous ophthalmic rete mirabile) at the ventrotemporal angle of the eye. The present study reveals the ultrastructural anatomy and the compact, three‐dimensional arrangement of vessels in this rete, which had been shown by previous investigators to function as a countercurrent heat exchanger. Vessels from this rete include the supraorbital and infraorbital arteries, which supply the eyeball anteriorly, and the ophthalmotemporal artery, which supplies the eyeball posteriorly. The internal ophthalmic and ethmoidal arteries, branches of the cerebral carotid artery, anastomose with the ophthalmotemporal artery posteriorly. Blood is distributed to the eyeball anteriorly by two ring arteries: the iridial ring artery, which circumscribes the iris and which receives blood from the long ciliary and infraorbital arteries; and the more peripheral, ciliary ring artery, which receives blood mostly from the infraorbital and ethmoidal arteries. Within the iris is a dense, freely anastomosing bed of capillaries which extends to the edge of the pupil and then loops back beneath the ciliary body. The vasculature of the ciliary body consists of radially arranged plates of anastomosing capillaries of irregular bore which mimic the contours of that organ, but permit changes in pupil diameter. The present study demonstrates the three‐dimensional anatomy of the very dense capillary net of the choriocapillaris deep to the retina and the capillary mass of the pecten, and thus supports the finding of earlier investigators that nutrients diffusing from these structures nourish the avascular retina. The pecten consists of a pleated sheet of freely anastomosing capillaries which protrudes into the vitreous body from near the optic nerve. The choriocapillaris and the pecten are supplied by branches of the ophthalmotemporal artery: the former by numerous short posterior ciliary arteries, the latter by two or three arteries which further divide into one or two smaller vessels for each of its folds. Veins of the choroid layer at the periphery of the anterior surface of the eyeball, and to some extent on its lateral walls, are revealed by the corrosion‐casting technique as unusual, flattened vessels of large caliber which lie in closely spaced parallel arrays. The large surface area thus created may function in heat dissipation. These veins join with others from the choriocapillaris to form a large dorsal and a large ventral posterior ciliary vein. Blood from the pecten and from the choriocapillaris in the nasal, central, and temporal regions of the posterior surface of the eyeball is drained by the ophthalmotemporal vein. Vascular casts of veins are often distinguishable from those of arteries by bore morphology and by the presence of valves, but also by the shapes of endothelialnuclear depressions left in the plastic. The high resolution obtained with the present technique reveals details of microvasculature and of vessel distributionin the avian eye not previously described. Names for some of these vessels are sugg

ISSN:0002-9106    

DOI:10.1002/aja.1001700206

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

年代:1984

数据来源: WILEY

摘要:

AbstractA morphologic and morphometric examination of the major cerebral blood vessels in the dog was carried out to determine whether there were vasa vasorum in these arteries and what features might be associated with them. True vasa vasorum confined to the media were not seen in any of the vessels examined. Microvessels confined to the adventitia, however, were found in the internal carotid and vertebral arteries but not in the basilar, middle cerebral, or anterior spinal arteries. Animal size, vessel size as determined by adventitial and medial area, and the number of smooth muscle cell lamellae were not associated with the presence of these adventitial vessels; they occurred only in arteries with both an intra‐ and extradural portion. It therefore appears that most canine cerebral arteries do not have vasa vasoru

ISSN:0002-9106    

DOI:10.1002/aja.1001700207

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

年代:1984

数据来源: WILEY

摘要:

AbstractIn the sheep conceptus, individual intraepithelial binucleate cells first appear at 14 days post‐coitum (d.p.c.); and by 16 d.p.c. they form 15‐20% of the trophectoderm where it is apposed to the caruncular sites of initial attachment to the uterine epithelium. These binucleate cells and their derivatives can be recognized in the placenta by electron microscopy after selective staining of their Golgi body and its products, the numerous characteristic granules. Between 16 and 24 d.p.c. the uterine epithelium transforms to syncytial plaques. Evidence from ultrastructure and serial semithin sections indicates that this transformation is initiated by migration of fetal binucleate cells up to the microvillar junction and their fusion with individual uterine epithelial cells, producing trinucleate fetomaternal hybrid cells. These cells then appear to release their granules to the endometrium. It is suggested that continued binucleate‐cell migration and fusion with the trinucleate cells, together with displacement and/or death of the remaining uterine epithelial cells, produces the plaques of syncytium that cover the entire caruncle by 20‐24 d.p.c. This caruncular syncytium, in which no nuclear division has been found, expands enormously in area during the formation and maintenance of the cotyledons, deriving its nuclei from binucleate mi

ISSN:0002-9106    

DOI:10.1002/aja.1001700208

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

年代:1984

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001700201

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

年代:1984

数据来源: WILEY