摘要:

The embryonic growth curves of 38 individual organs and tissues in the mouse and 19 in the rat are given. A method is presented for the estimation of the confidence interval of the time points of the breaks in the growth curves. In some instances, breaks in the organ curves in the mouse coincided with those noted for the whole embryo, at 10.7, 14.5 and 18.1 days, but they also occurred at other times, i.e., 9.4, 12.1, 13.3, and 16.9 days; we call these times ‘phase transitions’. The relations between cell multiplication and other factors influencing volume increase are discussed, and also the relation between cell multiplication and changes in shape. Some implications of our work on growth for development in general are put forw

ISSN:1422-6405    

DOI:10.1159/000145173

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The claim that the hypertrophic cartilage of a transversely divided 9-day chick tibia is able to induce the differentiation of osteoblasts when placed against the fibrous periosteum of a second, intact, 9-day tibia in vitro, is refuted. Tibia from 7- and 9-day-old chick embryos were transversely sectioned through either the diaphysis or epiphysis and these diaphyseal and epiphyseal grafts were then placed in close association with the fibrous periostea of intact, host tibiae of the same or different ages, at either the diaphyseal or epiphyseal level. All of the sixteen possible combinations of paired tibiae were established in organ culture for 7 days on three types of culture media and two types of atmospheres. In response to the close contact established when diaphyseal grafts were used, the fibrous layer of the periosteum underwent hyperplasia to form fibroblasts at the contact site. Contact of the graft with the periosteum was not sufficient to allow osteoprogenitor cells to accumulate, to differentiate into osteoblasts, or to deposit osteoid. We concluded that the outer, fibrous layer of the periosteum is fibroblastic and not osteblastic.

ISSN:1422-6405    

DOI:10.1159/000145174

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Using light- and electron-microscopic techniques, a quantitative histological study of the rat saphenous nerve has been carried out. The distribution of myelinated fibre diameters was bimodal; while that of the unmyelinated axons was unimodal. The variation of myelin sheath thickness with axon diameter was non-linear; two straight lines were found to fit the data best. The variation of g (axon diameter/total fibre diameter) with total fibre diameter was also nonlinear, being best fitted by two lines – one straight, the other slightly curved. The number of unmyelinated axons per Schwann cell process was examined. The ratio of unmyelinated axons to myelinated fibres was 3.42:

ISSN:1422-6405    

DOI:10.1159/000145175

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

In the cartilage epiphysis of newborn, 8-, 30-, and 60-day-old Sprague-Dawley rats, 5’-nucleotidase, adenosine triphosphatase, alkaline and acid phosphatase activities were found. The main centre of activity of nearly all enzyme reactions is situated, with only small temporal differences in animals of all age groups in the middle and distal cells of the column cartilage, the proximal hypertrophic cells and the chondrocytes of the opening zone. The cells of the tangential layer in the articular cartilage of newborn and 8-day-old rats demonstrate 5’-nucleotidase activ

ISSN:1422-6405    

DOI:10.1159/000145176

出版商:S. Karger AG    

年代:1980

数据来源: Karger

ISSN:1422-6405    

DOI:10.1159/000145177

出版商:S. Karger AG    

年代:1980

数据来源: Karger