摘要:

An account of the early development of the human brain has been prepared from the data available for the Carnegie Collection, as well as from published information from other sources. Although the site of the neural plate can be discerned at stage 7, the first visible indication of the nervous system is the neural groove in certain embryos of stage 8, in which the embryonic disc measures more than 1 mm and the notochordal process at least 0.3 mm. The progressive fusion of the neural folds during stage 10, and the closure of the rostral and caudal neuropores at stages 11 and 12, respectively, are detailed with further precision than hitherto. It is emphasized that the major subdivisions of the human brain do not begin as vesicles, but as enlargements of the open neural folds at stage 9. The relationships of the neuromeres to the otic region, the somites, and the neural crest are clarified and illustrated. The early appearance of the telencephalon medium (before cerebral vesicles have formed) is stressed, and the terminological implications for the subdivisions of the brain are discussed.

ISSN:1422-6405    

DOI:10.1159/000145061

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The brains of young adult male and female Sprague-Dawley rats were studied with the electron microscope to determine the full ultrastructural picture of two types of perivascular granular cell. One of these, referred to here as the type I cell and described by both light and electron microscopy by several authors, including ourselves, has been reported to be a mast cell (MC) almost identical to MCs outside the CNS. The other, referred to here as the type II cell and described by many authors under almost as many names, was dealt with fully by Ibrahim in several reports and regarded by him as a type of MC. It is felt that the results warrant the conclusions that the type I cells are indeed MCs, while the type II cells are closely allied to the type I cells and probably better adapted to the function they subserve in the CNS of mammals. The similarities between the two cell types probably outnumber the dissimilarities and even these have their counterparts in MCs outside the CNS. The problem of the possible confusion between the type II cells and macrophages, whether reportedly within vessel walls or in the form of modified or special ‘pericytic’ microglia, is discussed. It is concluded that there is no justification for regarding these cells as macrophages. Because of the similarity between the type II cells and MCs, and because of the high lipid content of the type II cells, it is suggested that these elements be called neurolipomastocytes or neurolipomastocytoid ce

ISSN:1422-6405    

DOI:10.1159/000145062

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The existence of a peculiar structural pattern of complementary villi and pores was observed on the squamous surfaces of palms and soles. These features, which might be considered as acquired and adaptive cell surface modifications, proved to be more conspicuous during a period of rat and human postnatal development.

ISSN:1422-6405    

DOI:10.1159/000145063

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Recent interest in vascularity in relation to peptic ulceration poses the question of relationship between three entities: (1) site of gastro-jejunal (post-anastomotic) ulcer, (2) site of the anastomotic line and (3) site of junction and possible vascular anastomosis between gastric and jejunal circulations in the region of the anastomosis. Vascular injection studies in dogs show that the main gastric and jejunal circulations run up to, but do not communicate across, the surgical anastomosis, there being a line of least vascularity at the anastomosis. Since anastomotic ulcers occur distal to the anastomotic line, this supports the view that such ulcers are situated wholly in an area of jejunal circulation.

ISSN:1422-6405    

DOI:10.1159/000145064

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

A histological study of the testis of the camel has been carried out; this includes the description of the different cell types of the testis, stages and frequency of the cycle of the seminiferous epithelium. The testis is characterized by the presence of abundant Leydig cells found in large masses in the intertubular areas and in the mediastinum. The cycle of the seminiferous epithelium was divided into eight stages (I–VIII) according to the method of Ortavant. The frequency of the stages I–VIII of the cycle is not affected by season and was found as follows: I: 21.93%; II: 11.07%; III: 13.42%; IV: 8,24%; V: 10.32%; VI: 9.34%; VII: 9,25%; VIII: 16.

ISSN:1422-6405    

DOI:10.1159/000145065

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Electron-microscope study of chick tendon fibroblast revealed a constant ultra-structural finding of a microtubular-microfibrillar system and an intimate relationship which existed between the microtubular-microfibrillar system and secretory vacuoles. Additionally, the data from this study suggest a mechanism by which newly synthesized collagen molecules are transported and secreted into the extracellular space to be organized into mature collagen.

ISSN:1422-6405    

DOI:10.1159/000145066

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The origin, course and regions supplied by the ethmoidal arteries were studied on 30 injected adult heads. After branching off, the anterior ethmoidal artery normally makes a single smooth loop by first coursing forwards and then, reversing itself towards the anterior ethmoidal foramen, it goes into the canal portion, likewise without bend or angularity. Occasionally, a common ethmoidal artery or a common source for the ethmoidal arteries is present. Very rarely does the artery fail entirely. As a rule, the posterior ethmoidal artery arises from the ophthalmic artery. Occasionally, however, it is missing or can even very rarely arise from the A.meningea media. The artery usually crosses over the superior oblique muscle while the anterior ethmoidal artery usually goes under the same muscle. In the fossa olfactoria, the ethmoidal arteries give off their most important dura and bone branches in the anterior cranial fossa and then continue into the walls of the cavum nasi. The courses and variations along with ipsi- and contralateral anastomoses are likewise demonstrated.

ISSN:1422-6405    

DOI:10.1159/000145067

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The cell masses of the diencephalon ofAmphisbaena darwini heterozonata are studied and confronted with those of other reptiles, specially with the burrowing ophidian Typhlopidae. The main differences are in the thalamus dorsalis. The amphisbaenids share with the Typhlopidae the absence of the lateral and pretectal geniculate bodies, and share with the squamate reptiles, differing from the typhlopids, the remaining structures of the dorsal thalamus, characterized by the well-developed nucleus rotundus. These features support the idea that the amphisbaenids could be situated within the Squamata at the same level as in Ophidia and Lacertilia. The adaptive processes toward a burrowing behavior have not been the same in amphisbaenids and in the typhlopids. The causes of the dissimilarities of the dorsal thalamus could be related to other sense and non-sense systems apart from the optic. The morphology of the elements of the cell masses has been studied by the Golgi method.

ISSN:1422-6405    

DOI:10.1159/000145068

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The frequency, morphology, symmetry and asymmetry of the retro-articular process of the human temporal bone are studied in 811 adult skulls, being 386 from whites (301 men and 85 women), 245 from Negroes (137 men and 108 women), 138 from mulattoes (94 men and 44 women) and 42 from Japanese (31 men and 11 women). In 1,591 out of the 1,622 observations there was an evident retro-articular process. It was classified according to its shape as mam-millary, pyramidal, tubercular, crest-like or molar. Furthermore, in each one of these above referred types the process showed to be large, middle or small in size. The author states that in 98.4% of the skulls studied an evident retro-articular process could be observed; it was symmetrical in 790 cases, asymmetrical in 713 cases. These results are against the literature on the subject because it has been stated that in the present-day man the retro-articular process is very rare and, when present, usually very small.

ISSN:1422-6405    

DOI:10.1159/000145069

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The pigeon olfactory nerve has been sectioned to explore the course of retrograde degeneration of the sensory neurons’ perikarya, which are located in the olfactory neuroepithelium. Both light- and electron-microscopic observations have shown that from 3 to 8 days after axotomy the sensory neurons undergo retrograde, irreversible degeneration. Following disappearance of the mature neurons, the basal cells of the neuroepithelium actively divide and differentiate into mature olfactory sensory neurons. Consequently, the basal cells represent true stem cells of the olfactory sensory neurons. The olfactory mucosa regains a structural organization close to normal in a period of 30–50 days after axotomy. These observations indicate that, when the primary olfactory neurons degenerate as a consequence of the experimental section of their axons, restitutio adintegrum of the sensory olfactory connections can be reestablished by new elements which differentiate from basal cells of the olfactory neuroepithel

ISSN:1422-6405    

DOI:10.1159/000145070

出版商:S. Karger AG    

年代:1979

数据来源: Karger