Granule formation in rat myeloid cells

Summary Rat bone marrow was fixed in glutaraldehyde, postfixed in osmium tetroxide, and processed for electron microscopy. The myeloid cells were arranged in order of maturation according to their successive compartments.On the basis of their differences in form, substructure, volume, and density five morphologically distinct types of developing granules are to be observed in neutrophil, two in eosinophil, and four in basophil, cells. Primordial granules appear in the interphase of the myeloblast, respectively in the early promyelocytes. The first granules in the neutrophils are pale, of homogeneous structure. These granules grow gradually denser with increasing condensation. In the myelocyte stage polymorphism is more pronounced. In the granulocytes, vacuoles and dense-cored vacuoles indicate the sites of granules. In the eosinophil line, the basophilic bodies decrease in number during differentiation. The eosinophil granules show fewer variations in the course of maturation than the neutrophils. The immature forms of the basophil granules are relatively large, pale, and of globular structure; they undergo condensation and show gradually higher density.Sites of granulogenesis in the rat are first of all the Golgi apparatus and, possibly, the cisternae in the endoplasmic reticulum. On occasion, bodies in a transitional stage between a mitochondrium and a granule can be observed, but whether they may have a bearing on the problem of granulogenesis is an open question.     

Occurrence of lysosomes and the differentiation of rat liver cells

Summary The occurrence of lysosomes has been investigated electron microscopically and cytochemically in cells of rat liver in the course of ontogenesis.It has been found that primary lysosomes occur during the whole period under investigation and that they originate from the Golgi complex. Some of them assume the appearance of multivesicular bodies. Acid phosphatase activity is lower at the prenatal stage than after the birth. The occurrence of secondary lysosomes proceeds in two stages. Secondary lysosomes appear in a high number at the beginning of differentiation of the liver diverticulum (10–12 day of embryonic life). On the subsequent days they are, with few exceptions, no more present. At the end of the embryonic period (starting with the 20th day) and especially after the birth, they progressively grow in number and move from the region of central cytoplasm peripherally towards the bile capillary.Differences in occurrence of secondary lysosomes are in connexion with reconstruction of the liver primordium at the beginning of liver development and with the change in metabolism of the liver cell after the birth.     

Effect of Antihypertensive Drugs on the “Intrinsic” Heart Rate

“Intrinsic” heart rate in man was measured by giving simultaneous atropine and propranolol and used to study the direct effect of antihypertensive drugs on the heart. Though the intrinsic and control heart rates decreased significantly following the administration of reserpine, there was no significant difference between high and low doses. No similar effects were observed with debrisoquine sulphate and methyldopa, though in high doses the latter produced a decrease which was of some statistical significance.