摘要:

AbstractTrophoblast‐uterine epithelial cell interrelationships were studied using implantation sites from the rat, rabbit, guinea pig, armadillo, bat and ferret. It was found that in all species trophoblast cells extend over several epithelial cells at the apposition stage of implantation. Trophoblast can adhere to the apical ends of uterine epithelial cells by primitive junctional complexes. More surprisingly, in most species desmosomal junctions are formed between trophoblast and the lateral aspects of uterine epithelial cells by primitive junctional complexes. More surprisingly, in most species desmosomal junctions are formed between trophoblast and the lateral aspects of uterine epithelial cells by primitive junctional complexes. More surprisingly, in most species forms the complementary protion of the apical junctional complexes with the adjacent luminal epithelial cells. Certain basement membranes appear to be barriers to trophoblast invastion in some species but not in others. There is little evidence that trophoblast is cytolytic, whereas all of the trophoblast examined gave some evidence of phagocytic activity, and the trophoblast of some of the more invasive forms showed evidence of being histolytic.It is suggested that the capacity of trophoblast to form junctions with epithelial cells is an important part of the implantation process, facilitating penetration of the endometrium without dislodgment of the blastocys

ISSN:0002-9106    

DOI:10.1002/aja.1001250102

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

年代:1969

数据来源: WILEY

摘要:

AbstractHindlimb muscles of the rat were studied in serial section with enzyme histochemical methods. Muscle fibers, both extrafusal and intrafusal, were compared as to their relative succinic dehydrogenase and phosphorylase activity, indicative of oxidative and glycolytic metabolism respectively. The superficial fascicles of a number of white (fast‐twitch) muscles are composed almost exclusively of glycolytic (type A) muscle fibers, whereas the deep fascicles contain a mixture of oxidative (type B) and oxidative‐glycolytic (type C) fibers. Muscle spindles are found only among the deep fascicles of these fast muscles. Neither the soleus, a red (slow‐twitch) muscle comprised mainly of type B fibers, nor the middle lumbrical muscles, with a fairly uniform distribution of several fiber types, exhibit so specific a spindle disposition. Thus a close spatial relationship exists between spindles and certain types of muscle fibers, presumbly representing specific types of motor units. Within the spindles, the nuclear‐bag intrafusal fibers are generally of types A and B, and of a third variety characterized by both low oxidative and low glycolytic activity. The latter fiber‐type is not commonly observed in the extrafusal musculature. Nuclear‐chain intrafusal fibers resemble type C fibers. Speed of contraction and enzymes of energy metabolism of extrafusal fibers are known to be neurally regulated. The several types of histochemically distinguishable intrafusal fibers probably reflect differences in motor innervation and possibly differing contracti

ISSN:0002-9106    

DOI:10.1002/aja.1001250103

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

年代:1969

数据来源: WILEY

摘要:

AbstractNucleoside phosphatase activity was studied in glutaraldehyde‐fixed rat myocardium. At pH 7.2, ATPase, nucleoside diphosphatase and thiamine pyrophosphatase activity were demonstrated in the transverse elements of the sarcoplasmic reticulum of ventricular fibers and in the subsarcolemmal cisterns of atrial and ventricular muscle cells. The remainder of the sarcoplasmic reticulum of atrial and ventricular fibers showed reactions only with nucleoside diphosphates. The T tubules and intercalated discs of ventricular muscle reacted strongly with nucleoside monophosphates at pH 7.2; atrial myocardium showed this reaction only in the intercalated discs and in the spaces between closely apposed muscle cells.Thiamine pyrophosphatase and nucleoside diphosphatase were demonstrated in the Golgi apparatus of both atrial and ventricular muscle cells; however, reactive cisterns were more numerous in atrial than in ventricular myocardium. These enzymes were also demonstrated in some of the membranes surrounding the specific cytoplasmic granules of atrial muscle cells. Acid phosphatase activity was also detected in some of these membranes when cytidine monophosphate was used as substrat

ISSN:0002-9106    

DOI:10.1002/aja.1001250104

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe germinal crescent in the chick embryo is characterized by small, PAS‐positive, nonglycogen granules from 1.5 to 5 μ in diameter. The primordial germ cells (PGCs) were found to originate in and separate from the germinal crescent endoderm through stage 7 (2 somites). Shortly after separation most of the granules in the PGCs lost their organization and the PAS‐positive material was distributed irregularly throughout the cytoplasm. A few of these granules remained within the cells indefinitely. Glycogen of an agranular nature which had shifted to one pole of the cell was observed at stage four. Granular glycogen which was distributed throughout the cytoplasm was not observed prior to stage 7 or 8.Cell counts on individual embryos showed noticeable variations as to the number of germ cells between embryos of the same stage. For example, in stage 4 embryos the minimum number of cells counted, including attached and free, was 78 and the maimum 169, while in stage 9 the minimum was 83 and the maximum 469 cells. After separation the germ cells were observed almost anywhere between the ectoderm and the endoderm although the majority remained in the area where they origin

ISSN:0002-9106    

DOI:10.1002/aja.1001250105

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

年代:1969

数据来源: WILEY

摘要:

AbstractThis study was designed to demonstrate quantitative growth trends in the human upper face region before birth. Photographs of 68 sagittally sectioned fetal heads were measured using a series of linear and angular measurements for changing height, length and shape. Cross‐sectional types of data were treated with a statistical model which tested for linearity of the data, correlation between growth changes and increasing fetal age, significance of the differences between rates of change in related upper face regions and the general significance of the trends shown in the study.Pooled data for the second and third trimesters suggested three distinct growth trends. Linear measurements of the cranial base, nasal area, and plate correlated significantly with increasing crown‐rump length. Finally, a composite upper face profile for the sample suggested a relative migratio of the region downward and forward away from the anterior cranial base and the hypophyseal fossa. These three trends collectively demonstrated that the pattern of upper facial growth before birth involves progressive enlargement of a relatively static profile. It should be understood that this pattern is a group trend as shown by cross‐sectional sampling of many individuals over a period of time with no individual being measured more than once. Conversely, variabilities in a specific individual's growth are most appropriately demonstrated by measuring that individual several times throughout some time span, i.e., by longitudinal sampling. Studies of the human fetus are restricted generally to the cross‐sectional sampling technique.The close similarly of these prenatal trends with those reported for postnatal craniofacial growth suggests that certain patterns of facial growth in childhood can be seen as early as the beginning of the fetal period and emphasizes the continuum of human deve

ISSN:0002-9106    

DOI:10.1002/aja.1001250106

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

年代:1969

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001250101

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

年代:1969

数据来源: WILEY