摘要:

AbstractThe postnatal differentiation of acinar cells in rat submandibular gland was studied by staining with periodic acid‐thiosemicarbazide‐silver proteinate to identify carbohydrate‐containing macromolecules in the electron microscope. This method revealed glycogen particles and internal substructure in the secretory granules of developing acinar cells. On the basis of morphologic and histochemical criteria three phases of acinar cell development were defined. In the pro‐acinar phase, during the first week after birth, pro‐acinar cells and terminal tubular cells were the main components of the terminal tubules in the rudimentary gland. The secretory granules of the pro‐acinar cells contained speckled or rod‐like substructures which stained intensively for carbohydrates and were digested by proteolytic enzymes. During the second to third week after birth, which is the immature‐acinar‐cell phase, thread‐like substructures were seen in the secretory granules. These structures, which were not digested by proteolytic enzymes, disappeared gradually. The acinar cells of 4‐week‐old or older rats displayed no particular substructure in the secretion granules and represented the final, matu

ISSN:0002-9106    

DOI:10.1002/aja.1001460302

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe dog and cat are useful experimental animals, and information regarding their cerebrovascular patterns and the source of blood supplying their brains is important. Blood vessels to brains and heads of cats and dogs were injected with various contrast media. Extracranial and intracranial arteries were studied grossly and in cleared sections.The proximal part of the internal carotid artery is small in the dog and nonfunctional in the cat. The largest single source of arterial blood supplying the brains of these species comes from the maxillary artery over an anastomotic ramus leading to an internal rete mirabile enmeshed in the cavernous sinus. The distal segment of the internal carotid arises from this anastomosis. The brainstem of both animals is supplied by C1branches of the vertebral arteries, and in the dog an occipital ramus makes a large contribution to it. In addition to an internal rete mirabile, the cat possesses a large external rete mirabile surrounding the maxillary artery and giving rise to all branches in the area. It is functionally equivalent to the ramus anastomoticus in the dog.Arterial patterns over brains of Carnivora are similar. They resemble those of lower mammals more than those of primates. Extensive extracranial arterial anastomoses located in the orbit, retia mirabilia and neck musculature are significant and make it difficult to render the brains ischemic.

ISSN:0002-9106    

DOI:10.1002/aja.1001460303

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

年代:1976

数据来源: WILEY

摘要:

AbstractThis investigation describes the differentiation of the type I pneumocyte from undifferentiated pulmonary epithelium. Cells lining subpleural alveolar septa were photographed from serial sections with the electron microscope and a three dimensional representation of each cell was obtained by transferring the contours of the cell membranes from micrographs to transparent plastic sheets which were then spaced to scale and stacked. The results of this study indicate that: (1) the only reliable criterion for differentiating between type I and type II cells is the commencement of attenuation of the type I cell; (2) differentiation of the type I cell occurs via the formation of one or more cytoplasmic attenuations that eventually fuse peripherally, thereby surrounding the unattenuated cell soma; (3) with respect to individual cells, blood‐air barriers tend to form in distal areas of the attenuating cytoplasm before proximal areas; (4) both type I and type II pneumocytes retain certain characteristics that reveal their common origi

ISSN:0002-9106    

DOI:10.1002/aja.1001460304

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

年代:1976

数据来源: WILEY

摘要:

AbstractVascular casts of the pituitary‐median eminence complex from seventeen adult female rabbits were examined with the scanning electron microscope. The results of this study confirm the presence of a single capillary bed common to the entire neurohypophysis. Arterial supply to the rabbit pituitary is only to the neurohypophysis. A direct supply to adenohypophysis was not found.Within the median eminence there are an external and internal capillary plexus. The internal capillary plexus is directed toward the infundibular recess of the third ventricle. It does not receive a direct arterial supply but derives its blood supply from the external plexus before draining to the adenohypophysis.Vessels of the posterior median eminence are confluent with vessels of the infundibular stem.On the basis of these studies, it is proposed that the entire neurohypophysis, not simply the median eminence, serves as the final common pathway to the glandular pituitary. It is also proposed that in the median eminence, vessels are organized to deliver blood containing hypothalamic releasing and inhibiting hormones as well as posterior lobe neural hormones (antidiuretic hormone and oxytocin) to the ventricular surface for subsequent transport to cerebrospinal fluid and distribution to the brai

ISSN:0002-9106    

DOI:10.1002/aja.1001460305

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

年代:1976

数据来源: WILEY

摘要:

AbstractPrenatal development of the eye in golden hamsters is described at the light microscopic level as twelve periods based on salient morphological features.Period oneincludes shallow and deepened optic sulci in the cephalic neural plate and closing prosencephalon.Period twoshows V‐shaped prosencephalic evaginations, andPeriod three, bulbous vesicles. Contact of the retinal disc and lens placode atPeriod fourprecedes presumptive retinal invagination and lens pit formation duringPeriod five. DuringPeriod sixan open lens vesicle, precociously expanded dorsal and lateral optic cup regions and widespread optic fissure margins are evident. A spherical lens lumen, deepened optic cup and narrow optic fissure characterizePeriod seven. AtPeriod eightposterior lens fibers are elongated, the optic cup is expanded ventrally, and optic fissure margins are juxtaposed or fusing. ByPeriod ninethe lens lumen is nearly or completely occluded, the optic fissure is essentially fused and axonal fibers are exiting from the globe. DuringPeriod tencorneal components are associated, axonal processes extend to the diencephalon, and lid folds cover more than half of the cornea. ByPeriod eleveneyelids are fused. Anteriorly the pigmented epithelium is thickened and densely pigmented; outer and inner neuroblastic retinal layers are clearly distinguishable.Period twelveis marked by conspicuous anterior folds of pigmented epithelium; a relatively anuclear zone virtually separates outer and inner neuroblastic layers of the retin

ISSN:0002-9106    

DOI:10.1002/aja.1001460306

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

年代:1976

数据来源: WILEY

摘要:

AbstractTendrils have been reported to radiate from luminal surfaces of proximal tubules in rat kidneys by Andrews and Porter ('74) using scanning microscopy, but they were not seen by Bulger et al. ('74). In this study, the perfusion procedure of Andrews and Porter was re‐investigated. Tendrils were found only in regions which had characteristics of poor fixation. They were especially prominent if the perfusion pressure was purposely allowed to fall and subsequently increased to re‐expand the tubules. The tendrils could then be seen in all portions of the proximal convoluted tubule and not exclusively in the initial portion as previously repor

ISSN:0002-9106    

DOI:10.1002/aja.1001460307

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

年代:1976

数据来源: WILEY

摘要:

AbstractOsteopetrosis iniarats has been cured by combining whole‐body irradiation with infusion of spleen cells from a normal littermate. The cure, first seen radiographically and histologically as areas of resorption below the epiphyseal plates of long bones, progressed to produce marrow cavities of normal proportions. Treatment ofiarats with either radiation or normal spleen cells alone was not successful. Furthermore, osteopetrosis was induced in normal littermates when radiation was combined with infusion of mutant (ia) spleen cells. These results show that spleen cells contribute to the resorbing capacity of the skeleton and suggest that osteoclasts might have a hematogenous origi

ISSN:0002-9106    

DOI:10.1002/aja.1001460308

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

年代:1976

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001460301

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

年代:1976

数据来源: WILEY