摘要:

AbstractThe sequence of events in the development of the brain in human embryos, already published for stages 8‐17, is here continued for stages 18 and 19. With the aid of a computerized bubble‐sort algorithm, 58 individual embryos were ranked in ascending order of the features present. The increasing structural complexity provided 40 new features in these two stages. The chief characteristics of stage 18 (approximately 44 postovulatory days) are rapidly growing basal nuclei; appearance of the extraventricular bulge of the cerebellum (flocculus), of the superior cerebellar peduncle, and of follicles in the epiphysis cerebri: and the presence of vomeronasal organ and ganglion, of the bucconasal membrane, and of isolated semicircular ducts. The main features of stage 19 (approximately 48 days) are the cochlear nuclei, the ganglion of the nervus terminalis, nuclei of the prosencephalic septum, the appearance of the subcommissural organ, the presence of villi in the choroid plexuses of the fourth and lateral ventricles, and the stria medullaris thal

ISSN:0002-9106    

DOI:10.1002/aja.1001820402

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to determine histologically the distribution of microspheres (MSs) (14 μm), and hence the relative distribution of blood flow, in rat plantaris muscle relative to the fiber types (fast‐twitch‐oxidative‐glycolytic [FOG], fast‐twitch‐glycolytic [FG], and slow‐twitch‐oxidative [SO]). Three conditions were investigated: (1) preexercise standing; (2) treadmill locomotion at 15 m/min (fast walking); and (3) treadmill locomotion at 60 m/min (moderate galloping). The MS suspension (containing 1 × 106MSs) was infused into the ascending aorta via a catheter in the carotid artery under each of the 3 conditions so that MSs were distributed to the tissues in proportion to their respective blood flows. Sections (20 m̈m) of the plantaris muscle were cut and assayed for reduced nicotinamide adenine dinucleotide tetrazolium reductase (NADH‐TR) and myofibrillar adenosine triphosphatase (ATPase) activities so the fibers could be typed as SO, FOG, or FG. MSs were located in the NADH‐TR sections, and the fibers next to the MSs were classified and counted. The observed numbers of fibers of each type in each condition that were adjacent to MSs were compared to the predicted number of adjacent fibers based on the assumption the MSs were randomly distributed in the tissue. This analysis demonstrated that MSs (and blood flows) were preferentially distributed to SO fibers during preexercise, to SO and FOG fibers during slow locomotion, and to FOG fibers during fast locomotion. The data support the contention that blood flow is distributed in muscles of conscious animals as functions of fiber type an

ISSN:0002-9106    

DOI:10.1002/aja.1001820403

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

年代:1988

数据来源: WILEY

摘要:

AbstractPrimary olfactory and central projections of the nervus terminalis were investigated by injections of horseradish peroxidase into the olfactory epithelium in the African lungfish. In addition, gonadotropin‐releasing hormone (GnRH) immunoreactivity of the nervus terminalis system was investigated. The primary olfactory projections are restricted to the olfactory bulb located at the rostral pole of the telencephalon; they do not extend into caudal parts of the telencephalon. A vomeronasal nerve and an accessory olfactory bulb could not be identified. The nervus terminalis courses through the dorsomedial telencephalon. Major targets include the nucleus of the anterior commissure and the nucleus praeopticus pars superior. Some fibers cross to the contralateral side. A few fibers reach the diencephalon and mesencephalon. No label is present in the “posterior root of the nervus terminalis” (=“Pinkus's nerve” or “nervus praeopticus”). GnRH immunoreactivity is lacking in the “anterior root of the nervus terminalis”, whereas it is abundant in nervus praeopticus (Pinkus's nerve). These findings may suggest that the nervus terminalis system originally consisted of two distinct cranial nerves, which have fused–in evolution–in most vertebrates. Theories of cranial nerve phylogeny are discussed in the light of the assumed “binerval origin” of the

ISSN:0002-9106    

DOI:10.1002/aja.1001820404

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

年代:1988

数据来源: WILEY

摘要:

AbstractMorphological changes in skeletal muscle related to lenghening (eccentric) contractions have been noted by several laboratories. However, a systematic examination of skeletal muscle following repetitive ecentric ontractions is lacking. This study was undertaken to study lesions and determine their relative densities in rat soleus muscle 30 min following level or downhill treadmill exercise. Following fixation in situ by vascular perfusion, toluidine‐blue‐stained 1‐μm sections of the muscle samples selected at 73‐μm intervals were scanned with a light microscope. Three types of lesions were noted: focal disruptions in the A‐band, localized dissolution of Z‐lines, and clotting of muscle fibers. Soleus muscle from the caged controls and the tibialis anterior muscle from downhill‐exercised rats were essentially free of lesions. Eighty‐nine percent of the soleus m. lesions in the downhill runner group and 97% of those in the level runner group were A‐band disruptions. A‐band lesion density was significantly higher in the soleus muscle of the downhill runners compared to level runners with the highest incidence in the distal half. A‐band lesion density was lower in soleus muscles from level runners; however, the highest intramuscular incidence was in the proximal rather than the distal end. The results indicate that a disruption of the A‐band is a principal change within some skeletal muscle fibers 30 min following repetiti

ISSN:0002-9106    

DOI:10.1002/aja.1001820405

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

年代:1988

数据来源: WILEY

摘要:

AbstractDiethylstilbestrol (DES) treatment of a male Syrian hamster resulted in the development of a renal tumor and its widely scattered scrosal metastases. Cells in both the primary tumor and metastatic nodules contained secretory granules. The tumors were transplanted serially into DES‐supported and non‐DES‐supported host hamsters until DES‐independent tumors developed. Rabbit antiserum to mouse salivary renin and rabbit antiserum to rat kidney resin were reacted with sections of the primary tumor, metastatic nodules, and all transport tumors. The sections were stained by the PAP and Vector‐ABC‐AP procedures. Renin‐positive material was observed in all tumors. Plasma renin activity (PRA) was determined for the host hamsters carrying the renal tumor transplants and compared to the PRA values that had been determined for normal non‐DES‐treated male and female hamsters. It was found that the average PRA values of host hamsters carrying the tumor transplants were significantly higher than the

ISSN:0002-9106    

DOI:10.1002/aja.1001820406

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

年代:1988

数据来源: WILEY

摘要:

AbstractInnervation of the ultimobranchial glands in the chicken was investigated by immunohistochemistry, fluorescence microscopy and electron microscopy. The nerve fibers distributed in ultimobranchial glands were clearly visualized by immunoperoxidase staining with antiserum to neurofilament triplet proteins (200K‐, 150K‐ and 68K‐dalton) extracted from chicken peripheral nerves. The ultimobranchial glands received numerous nerve fibers originating from both the recurrent laryngeal nerves and direct vagal branches. The left and right sides of the ultimobranchial region were asymmetrical. The left ultimobranchial gland had intimate contact with the vagus nerve trunk, especially with the distal vagal ganglion, but was somewhat separated from the recurrent nerve. The right gland touched the recurrent nerve, the medial edge being frequently penetrated by the nerve, but the gland was separated from the vagal trunk. The left gland was innervated mainly by the branches from the distal vagal ganglion, whereas the right gland received mostly the branches from the recurrent nerve. The carotid body was located cranially near to the ultimobranchial gland. Large nerve bundles in the ultimobranchial gland ran toward and entered into the carotid body.By fluorescence microscopy, nerve fibers in ultimobranchial glands were observed associated with blood vessels. Only a few fluorescent nerve fibers were present in close proximity to C cell groups; the C cells of ultimobranchial glands may receive very few adrenergic sympathetic fibers.By electron microscopy, numerous axons ensheathed with Schwann cell cytoplasm were in close contact with the surfaces of C cells. In addition, naked axons regarded as axon terminals or “en passant” synapses came into direct contact with C cells. The morphology of these axon terminals and synaptic endings suggest that ultimobranchial C cells of chickens are supplied mainly with cholinergic efferent type fibers. In the region where large nerve bundles and complex ramifications of nerve fibers were present, Schwann cell perikarya investing the axons were closely juxtaposed with C cells; long cytoplasmic processes of Schwann cells encompassed large portions of the cell surface. All of these features suggest that C‐cell activity, i.e., secretion of hormones and catecholamines, may be regulated by ne

ISSN:0002-9106    

DOI:10.1002/aja.1001820407

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe secretory pathway of clentin phosphoproteins in rat incisors was studied by electron microscopic radioautography after the injectionof3H serine, and the results were compared with those using3H‐proline as a tracer.Five min after injection of3H‐serine, radioactivity was found in the rough endoplasmic reticulum. At 10 min, silver grains were observed over the spherical portions of the cisface of the Golgi apparatus. At 20 min after injection, silver grains were seen over the cylindrical portions of the transface of the Golgi apparatus. The secretory granules showed the strongest reaction from 20 min to 1 hr. At 45 min, a significant labeled band appeared at the mineralization front. At 1 hr, the labeling at the mineralization front began to appear in the mineralized dentin, and after 12 hr this labeled band was located within the mineralized dentin.The pathway of3H‐proline was essentially the, same The pathway of H‐proline movedmrore slowly as that of3H‐serine,3H‐proline than3H‐serine, especially in transit from the rough endoplasmic reticulum to the Golgi apparatus. Secretory granules were heavily labeled from 30 min to 1 hr after injection of3H‐proline; no labeling was found at the mineralization front at 45 min. The labeling seen initially over the predentin was over the mineralized dentin no earlier than 6 hr after injection.The labeling pattern with3H‐serine is closely related to the localization of phosphoproteins, whereas the pattern with3H‐proline reflects the production of collagen rather than of phosphoproteins. The present radioautographic results indicate that dentin phosphoproteins are related to secretory granules and are secreted by Odontoblasts at the mineralization front and also that phosphoproteins are involved in the process of mineralization of the

ISSN:0002-9106    

DOI:10.1002/aja.1001820408

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis study addressed the problem of how growth of Craniomandibular muscles, tendons, and bones influences the acquisition of oromotor skills and biomechanics of feeding in the laboratory rat (Rattus norvegicus). Rats representing a 6.6‐fold size range were dissected, and muscles, tendons, and mandibles were weighed. Cross‐sectional areas of tendons and bones providing attachment surfaces for muscles were estimated. Ontogenetie scaling of Craniomandibular muscles, tendons, and bones was described by using linear regression models, and departures from size‐required compensations were used to characterize changes in oromotor function. A two‐dimensional model was developed which permitted calculation of mechanical advantages of four masticatory muscles; the model was used to show how mandibular growth and tooth eruption influence the biomechanics of rat feeding. Relative to mandible weight, most jaw muscles scaled either isometrically or positively, tendon cross‐sectional areas scaled isometrically or negatively, and bone surfaces scaled negatively. With the exception of the superficial masseter and internal pterygoid muscles, mechanical advantages did not change significantly during mandible growth. Growth patterns of Craniomandibular muscles, tendons, and bones contribute significantly to changes in morphology and oromotor

ISSN:0002-9106    

DOI:10.1002/aja.1001820409

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

年代:1988

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001820401

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

年代:1988

数据来源: WILEY