摘要:

Bone remodelling of post-extraction socket was studied in the past by various methods. In the present work, the process was studied with the scanning electron microscope (SEM). The SEM is essential for a three-dimensional description, particularly when hard tissues are involved. Initiation of healing on the first week was characterized by formation of delicate spongy bone. The trabeculae were distributed in a centrifugal pattern around the interradicular bone. Socket healing on the second week consisted of thickened, regularly distributed trabeculae. This was accompanied by resorption and flattening of the peri-socket sharp ridges. The third and fourth weeks were characterized by small bone marrow spaces and a gradual transformation of the trabecular bone to one of cortical-compact nature. The typical characteristics of resorbing, resting and forming surfaces were detected in all phases of socket healing. Two major patterns of ossification could be shown: Firstly, calcification of collagen bundles in osteoblastic lacunae. Concentrations of such lacunae were related to periosteal activity and were also found in areas most probably occupied previously by blood vessels. Another pattern of mineralization was in the form of globular calcospherites and is reminiscent of calcification of ground substance.

ISSN:1422-6405    

DOI:10.1159/000144740

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The ventriculus mesencephali is localized in front of the cerebellum and forms a recessus of the dorsal wall of the aquaeductus mesencephali. The ependyma was found one-layered; in some places clusters of cubic or cylindrical ependymal cells occur. Some cells show basal processes. Supra-ependymally there are homogeneous globules and intraventricular nerve fibres. The occurrence of different types of ependymal cells indicates a morphological variability of ependyma even within this small part of the ventricle system of the brain.

ISSN:1422-6405    

DOI:10.1159/000144741

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The fine structure of the retinal epithelium, Bruch’s membrane and choriocapillaries has been studied by electron microscopy in the spectacled caiman (Caiman sclerops). The retinal epithelium throughout most of the retina is morphologically very typical of that described for other vertebrates. This typical appearance involves a single layer of pigmented cuboidal cells with extensive basal (scleral) infoldings and numerous apical (vitreal) processes enclosing photoreceptor outer segments. A semicircular area of the retinal epithelium in the superior fundus is, however, further specialized as a tapetum lucidum. The reflecting material consists of a large array of guanine, diffusely scattered within the epithelial cells. Centrally in the tapetal area, no melanosomes are found, indicating a non-occlusible tapetum. At the edge of the tapetum, however, both guanine crystals and melanosomes are found within the epithelial cells. In most other respects, the morphology of the epithelial layer in the tapetal region is not strikingly different from that in the non-tapetal area. Bruch’s membrane everywhere displays the typical pentalaminate structure described for most vertebrates. The choriocapillaris is also typical in that numerous fenestrations are present in the endothelium bordering Bruch’s mem

ISSN:1422-6405    

DOI:10.1159/000144742

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

In the lateral musculature of the axolotl tail a multipennate arrangement of muscle fibres is found in the 3rd postanal myomere and all following myomeres. This arrangement appears in larval stages as soon as the myomeres concerned are fully differentiated. Within a myomere a uniform degree of contraction of the muscle fibres may be achieved either by helical arrangement as seen in Teleosts, by diminishing fibre length in medial direction or by a combination of both phenomena. The relation between muscle fibre length and angle of insertion in the myomeres showing pennate arrangement is approximated by the Benninghoff and Roll-häuser equation but the values recorded deviated systematically from the values calculated. In the rather slender tail of the axolotl the transition from the helical or parallel fibre system into the pennate arrangement will be in favour of the development of relatively strong bending moments in the region concerned while a reasonable uniformity of the rate of contraction is maintained

ISSN:1422-6405    

DOI:10.1159/000144743

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The effect of denervation on △5-3β-hydroxysteroid dehydrogenase (3β-HSD) activity with pregnenolone as substrate was studied during pregnancy. The enzyme activity, that is interpreted as the capacity to secrete progesterone, was studied in both control and experimental pregnant rats. The ovaries of experimental rats were denervated 96 h prior to sacrifice. Denervation during early pregnancy did not affect 3β-HSD activity in the interstitial gland (IG) and corpus luteum (CL). However, denervation resulted in decreased activity in both the IG and CL on days 10, 14 and 18. This reduced activity is interpreted as a decreased capacity of denervated ovaries to synthesize progesterone at this time in pregn

ISSN:1422-6405    

DOI:10.1159/000144744

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The distribution of autonomic nerves was studied at the ultrastructural level in guinea pig, hamster, mouse and rat parotid glands employing the potassium permanganate fixation/staining technique. In the periacinar connective tissue numerous unmyelinated nerves were observed in all the glands examined. Two types of axonal enlargements were encountered, one contained small, dense-cored vesicles (500–600 Å in diameter) as well as a few large (∼ 1,000 Å in diameter), the other exhibited numerous agranular vesicles (500–600 Å in diameter). In all glands, axons devoid of Schwann cell investment were visualized at the base of the acinar cells, inside the basement membrane and in intimate contact with gland cells. In addition, axonal enlargements of both types were encountered in the intervening space between neighbouring acinar cells. Whereas nerve terminals within the gland epithelium were extremely common in the rat, mouse and hamster, their frequency was much lower in the guinea pig. In addition, only parenchymal varicosities of the adrenergic (dense-cored vesicles) type were encountered in the latter species. No intraepithelial nerves were observed in the striated ducts. However, axonal enlargements were present in the subepithelial connective tissue and were most numerous in the hamster parotid gland. The above findings confirm the dual innervation of the serous acinar cells of the guinea pig, hamster, mouse and rat parotid glands by both parasympathetic and sympathetic nerves. Furthermore, there exists a close membrane-to-membrane contact between autonomic nerves and salivary gla

ISSN:1422-6405    

DOI:10.1159/000144745

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Methylazoxymethanol (MAM) causes a reduced development of cerebellum and medulla oblongata in rats. To study the effect of external factors on growth of the spheno-occipital synchondrosis, four litters of rats each of five animals were treated with MAM within 12 h after birth and sacrificed after 30 days. A similar number od control rats were sacrificed at the time when their skull length was equal to that of the experimental rats. Microradiographical and histological investigations showed that the cranial base lordosis was more pronounced in the MAM rats than in the controls, and that the width of the spheno-occipital synchondrosis was reduced mainly due to reduction in the central zone.

ISSN:1422-6405    

DOI:10.1159/000144746

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The ninth nerve was severed and the rat carotid body studied in the light and electron microscopes and after formaldehyde-induced fluorescence for its catecholamine content from 3 weeks to 13 months after operation. Minimal changes in the carotid body were observed. Hyperthrophy of the capsule cell was noticed up to about 2 months, after which time these cells appeared normal. Lysosomes in the capsule cells occurred more frequently and were larger than in normal carotid bodies. Discernible pathological alterations did not occur in the glomus cells, despite the absence of afferent terminals upon them. Atrophy of the carotid body was not noticed. The catecholamine content of the denervated carotid body was comparable to its innervated control and no nerve terminals were found on the glomus cells. Autonomic ganglion cells intrinsic to the carotid body varied in number from 1 to 8 and in location. The glomus cells do not receive any significant autonomic innervation, and the ganglion cells in the carotid body, perhaps sympathetic, probably innervate blood vessels. It is concluded that deafferentation has minimal morphological effects on the carotid body. The reactions of other receptor cells to deafferentation are compared with those of the glomus cells.

ISSN:1422-6405    

DOI:10.1159/000144747

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Two old conceptions on the development of the human lung, one of ‘stem and branch’, and the other of ‘eparterial’, do not seem to be reasonable to the present author. The lingual segment of the upper lobe of the left lung must be a portion corresponding to the middle lobe of the rig

ISSN:1422-6405    

DOI:10.1159/000144748

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The distal diaphyseal shafts of the rat tibia and fibula fuse postnatally, a process initiated by the seventh day with the formation of secondary cartilage that is subsequently replaced by endochondral ossification. The histological appearance of this fusion process is described. A homologous process occurs postnatally in the mouse. An analysis of some of the pertinent recent developmental, comparative and paleontological data indicated that extrinsic, bio-mechanical factors probably played a significant causal role in tibia-fibula fusions. The production of secondary cartilage is evoked by extrinsic forces, and these fusions were analyzed within the present concepts of intrinsic and extrinsic factors in skeletogenesis. It was concluded that the fusions currently reported fit well within the hypothesis of the functional matrix and that, such fusions between skeletal tissues are secondary, compensatory and mechanically obligatory responses to the prior demands of functionally related nonskeletal tissues and organs.

ISSN:1422-6405    

DOI:10.1159/000144749

出版商:S. Karger AG    

年代:1977

数据来源: Karger