摘要:

In order to establish the mechanisms underlying the morphogenesis of the so-called ‘elongated styloid process’, a comparative microradiographic and histological study was performed on 19 long and short processes. Some morphological differences between short and long processes are noticed. Numerous partially calcified cartilaginous islets are observed within the trabecular bone of very long styloid processes or covering their tip. Calcified fibrous tissue or calcified fibrocartilage sometimes contributes to the thickening of enlarged styloid processes. But the growth of the process does not seem to be due either to calcification or to ossification of the stylohyoid ligament, as thought in the past. Mechanical stresses stretching the second branchial arch during the fetal development probably induce a variable involvement of the different parts of Reichert’s cartilage in the morphogenesis of the styloid process. The so-called ‘elongated styloid process’ should thus be congenital. However, a further growth is still possible through the activity of the cartilaginous cap o

ISSN:1422-6405    

DOI:10.1159/000146753

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Whether secondary cartilage develops in the mammalian clavicle has been a matter of controversy. This study documents, in the embryonic mouse: (a) the onset of clavicular osteogenesis at 14 days of gestation (Theiler stage 22); (b) the appearance of secondary cartilage at 16 days of gestation (Theiler stage 24) and its persistence as a prominent cartilage until 18 days of gestation; (c) that the relative growth rate of the clavicle is much higher (0.097 mg/g body weight/day) between 16 and 17 days of gestation than at later ages (mean of 0.005 mg/g/day between 17 days of gestation and 4 days postnatally), and (d) that secondary cartilage failed to form in clavicles from 15-day-old embryos maintained in vitro. We conclude that secondary cartilage is a feature of the developing mouse clavicle, that it arises when the relative growth rate of the clavicle is highest, and that the most likely stimulus for differentiation of this cartilage is mechanical, muscle-based and associated with rapid relative clavicular growth.

ISSN:1422-6405    

DOI:10.1159/000146754

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Cortical explants from lamb kidney have been maintained in organ culture for up to 12 days. Early in culture, the tissue showed limited necrosis, but most tissue elements, especially those closest to the medium, significantly recovered by day 5. Glomerular peripolar cells were present for at least the first 3 days of culture. Neotubular formation was noted by day 5, often appearing as cyst-like structures. Glomerular podocytes lost their foot processes early in culture but apparently remained viable throughout the total culture period.

ISSN:1422-6405    

DOI:10.1159/000146755

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

A study of human cadaveric glenohumeral joints was undertaken to investigate the mechanism of external rotation during abduction. Previously explored extra-articular influences such as the coracoacromial arch and the rotator cuff muscles were removed from the specimens. A specially designed device was used to measure abduction in the scapular plane as well as any rotation of the humerus.The findings show that external rotation is a consistent feature of passive abduction in the plane of the scapula and could take place in the absence of extra-articular influences. The mechanism appears to lie either in the nature of the capsule or of the articular contours. A role for the intra-articular part of the long head of the biceps cannot be excluded.

ISSN:1422-6405    

DOI:10.1159/000146756

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Crystalloid inclusions were observed within nongranulated, folliculostellate pituitary cells 72 h after estrogen was withdrawn from primed male rats. Like crystalloid inclusions in macrophages reported by others, those observed in this study were associated with structures that appeared to be lysosomes. We suggest that crystalloid inclusions may be the result of phagocytosis, a function of folliculostellate cells proposed by us in a previous study.

ISSN:1422-6405    

DOI:10.1159/000146757

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The myosin isozyme distribution in the left ventricle and in the interventricular septum of rabbits was studied after 3 7,11,14 and 21 days of L-thyroxine (500 µg/kg/day) administration. Histochemical procedures were employed to identify V1 and V3 by their Ca2+ ATPase activity and their proportions were quantified through polyacrylamide gel electrophoresis. In the left ventricle, the subepicardium was the first to show the shift fromV3 to V1 followed by the subendocardium. The intermediate region became heterogeneous by 11 days and remained so until 21 days. The right subendocardial and the intermediate regions of the interventricular septum were heterogeneous in the normal rabbit and hyperthyroidism resulted in a shift from V3 to V1 in both the right and left subendocardial regions of the septum. Like the left ventricle, the intermediate region of the interventricular septum remained heterogeneous. Localized accumulations of collagen were seen in all regions of the left ventricle and interventricular septum. From these results we conclude that in thyrotoxic myocardial hypertrophy the isozymic shift from V3 to V1 is progressive, region-specific and is directly correlated with the period of hyperthyroidism in the first 2 weeks. Prolonged hyperthyroidism results in localized accumulation of collagen which does not exhibit any regional specificity

ISSN:1422-6405    

DOI:10.1159/000146758

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Directionally arranged dense connective tissue fibres were investigated in 21 specimens of the major duodenal papilla. Specimens were examined using a stereoscope, polarization microscopy and serial histological sections at three different planes. Directionally arranged dense connective tissue fibres spread in a deltoid pattern from the orifice of the major duodenal papilla and its intraduodenal part to the circular duodenal musculature. Connective tissue fibres crossing at different angles form a texture from the orifice of the major duodenal papilla to the distal choledochal duct. The functional significance of the dense connective tissue fibres, e.g. for the muscular system in the investigated area, is discussed as well as possible reasons for gallstone impactions.

ISSN:1422-6405    

DOI:10.1159/000146759

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The aim of this study is to demonstrate a case of a cadaver in which both left and right vertebral arteries had an abnormal origin. On the left, the artery arose directly from the arch of the aorta. On the right, a double-originating vertebral artery was seen. The literature on the variations of the artery is reviewed and a detailed morphometric study of the artery was carried out because of its importance for neurosurgeons.

ISSN:1422-6405    

DOI:10.1159/000146760

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

This study describes the general distribution of putative elastic fibers in the connective tissues that comprise the articular disk and some of the adnexal tissues of the rabbit temporomandibular joint. Joints were removed en bloc and processed for light-microscopic study. The fibroelastic tissues of the bilaminar zone of the articular disk and the various attachments of the disk to the mandibular condyle contained numerous elastic fibers. Since these morphologic data indicate the presence of many elastic fibers, we suggest that the rabbit temporomandibular joint may serve as a model system to study the functional consequences of selectively altering the quality or quantity of elastic fibers in these tissues.

ISSN:1422-6405    

DOI:10.1159/000146761

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

A study of the anatomy of the recurrent laryngeal nerve was made on 106 post-mortem cases and fixed dissecting-room cadavers. The usual position of the nerve was inthe tracheo-oesophageal groove. The nerve lay posterior to the inferior thyroid artery on the left side in most cases, while its relation was very variable on the right side. The inferior cornu of the thyroid cartilage was the best guide to the site of entry of the nerve into the larynx.

ISSN:1422-6405    

DOI:10.1159/000146762

出版商:S. Karger AG    

年代:1989

数据来源: Karger