摘要:

The size of the gametocytes of a leucocytozoon in young crows shows a wide variation in birds obtained in different localities. The host cell nucleus of infected cells may be pushed to one side, almost surround the parasite, or be intermediate between these extremes. Previous descriptions, given by various authors, ofLeucocytozoon sakharoffiandL.berestneffishow similar differences in these characters.L.berestneffiis considered therefore to be a synonym ofL.sakharoffi.

ISSN:1923-4287    

DOI:10.1139/cjr50d-001

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Thin paraffin sections of mouse lungs fixed by bronchial filling and stained intensely with iron haematoxylin show numerous and conspicuous epicytes of varying size, form, internal features, and density. Many have a dark lacelike cytoplasm with numerous small clear vacuoloids and a rounded opaque nucleus, while others stain more lightly and have large irregular vacuoloids, and a generally achromatic nucleus. Between these apparent extremes are graded intermediate forms. These epicytes may be arranged in a series perhaps connoting a functional or age sequence. Metabolic, endocrinic, and exocrinic roles have been suggested for them as well as the commonly attributed phagocytic function. The nuclei are often indented by contiguous vacuoloids. In partitions between alveoli, epicytes may have two, three, or even more air faces. Most of them are in the angles where septa between contiguous alveoli join. In many epicytes an extension may be seen arising from a larger nucleated part; and not infrequently two such extensions appear in the section. These processes may be more or less blunt and short, or long and thin; and their ends, of varying area, often form part of the wall of an alveolus, lying directly against the air space. On some of the narrow free ends were seen irregular spicules, which may be rudimentary cilia. In cross sections the processes are of circular or oval outline and are partially or completely buried in the connective tissue of the alveolar wall. Like the juxtanuclear part of the epicyte, the processes are bounded by a delicate cell membrane and show mitochondria in the cytoplasm between the vacuoloids. These processes presumably afford anchorages for the cells to the alveolar walls, and also surfaces through which nutriment may be absorbed from the contiguous capillaries. Epicytes that abut upon the pleura, interlobular septa, or sheaths of air and blood channels usually have only one air face and often appear without a process, partly sunken into the connective tissue, with a mass of frothy cytoplasm bulging into the alveolar space; but more rarely a process is visible arising from them. Release of epicytes from the alveolar walls may be possible, to create the relatively scarce free foam cells. Curious extended epicytes, some looking like dumb-bells, were often found.

ISSN:1923-4287    

DOI:10.1139/cjr50d-002

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Three strains of mice were used to study the effect of fostering on the growth pattern of the mouse. The strains used breed true for size and have been designated as "Large", "Small", and "Intermediate". The 14-day mean weight of mice that received milk from "Large" strain mothers is significantly different from those that received milk from either the "Small" or the "Intermediate" strain mothers. Although these differences tend to remain, they are not statistically significant at 140 days. The significance of these results are discussed in relation to the arithmetic and geometric concepts of polygenic growth.

ISSN:1923-4287    

DOI:10.1139/cjr50d-003

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Ultraviolet radiation of wave lengths from 2800 Å to 3100 Å, generated by a General Electric RS sun lamp, was used to irradiate eggs and alevins of the sockeye salmon (Oncorhynchus nerka). Mortality curves are presented for a series of measured dosages. Irradiation of eggs in the later stages of development produced a stimulating effect on the rate of hatching. These premature alevins, which hatched a month before the controls, were abnormal in several respects. The vertebral column was curved downward over the region of the heart, growth was retarded, the yolk was not utilized as rapidly as in the controls and pigmentation was delayed. The mortality was particularly high at the time of hatching and the process was abnormal. Histological examination of irradiated alevins revealed changes in the epidermis and fibroelastic layers of the skin. These were localized to the irradiated regions. Heavy doses produced severe degeneration of the epidermal layer with the formation of granules in the nuclei, the breakdown of the goblet cells, and subsequent desquamation. The changes were less extreme with lower dosages and in these fish a recovery began about 13 days after irradiation. Internal organs and tissues beneath the fibroelastic layers of the skin were not visibly affected by the irradiation.

ISSN:1923-4287    

DOI:10.1139/cjr50d-004

出版商:NRC Research Press    

年代:1950

数据来源: NRC