Further observations on the fine structure of the human spermatozoon

Summary The limiting membrane of the equatorial segment of the acrosome has a five layered appearance due to a thin dense layer apposed to the inner aspect of the unit membrane. Shorter localized areas with the same appearance are seen in the inner membrane of the anterior segment of the acrosome, but most of this membrane and all of the outer membrane of this segment show the tri-laminar unit membrane structure.In longitudinal sections the postacrosomal sheath is seen to consist of two different portions separated by a circumferential groove in the cell membrane. The anterior part is composed of a homogeneous dense layer from which regularly arranged projections extend toward the cell membrane. The posterior part is composed of a dense granular or homogeneous material apposed to the inner aspect of the cell membrane. This layer is limited posteriorly by a close union of the cell membrane with the nuclear envelope via a dense homogeneous material.In the implantation fossa the two layers of the nuclear envelope are interconnected by regularly spaced linear structures. The centriole found in this region has a constant orientation with respect to the long axis of the flagellum, and a system of numbering the triplets is proposed.The coarse fibers of the flagellum are finely cross striated with a period of 40 A. Near the abaxial surface of the fibers every forth line is somewhat thicker than the others, thus demarcating a major period of 160 A with three intraperiod lines of which the middle one is slightly thicker than the others.—A somewhat regular mode of termination of the tubular elements of the flagellum in the end piece is described.Supported by a Public Health Service International Postdoctoral Research Fellowship (number 1 F05 TW 1681-01), by Contract 69-2107 from the Center for Population Studies, National Institute of Child Health and Human Development, and by Statens Laegevidenskabelige Forskningsraad and P. Carl Petersens Fond, Denmark.     

Further observations on the osteometric discriminant function. The human clavicle

Linear discriminant functions of three terms have been calculated from the clavicular measurements published by F. G. Parsons. They have been applied to a known series of bones to assess their efficiency in sex-determination.     

Further observations on a cytoplasmic structure in the hamster oocyte

Summary Cytoplasmic structures consisting of two loops of “unit membrane” connected by a region of straight or curved 7-layered membrane are described. It is suggested that this appearance is caused by the collapse of a vesicle lined with a thin coating of electron-dense material.     

Further observations on the alleged presence of non-argyrophile argentaffin cells in the human gastro-intestinal tract

Summary The relationship between the argentaffin and argyrophile cells of the human gastro-intestinal tract has been studied by staining paraffin sections first by the Masson-Hamperl method and then by the Bodian method. The investigations confirms the author's earlier observation (Singh 1963) that all argentaffin cells of the human gastro-intestinal tract are also argyrophile and that there is no evidence to support the claim of Hellweg (1952) and of Hamperl (1952) regarding the presence of non-argyrophile argentaffin cells.     

Further observations on the phagocytosis of Candida albicans by hamster and human oocytes

Pathogenic yeast, Candida albicans, were incubated with hamster and human oocytes for up to 21 hours in order to determine the nature and time course of phagocytosis of these organisms. Aliquotes of the interacting cells were taken at various time intervals for electron microscopic examination. Some specimens had their zona pellucidae enzymatically removed prior to incubation with yeast, and these specimens showed the most extensive interaction and phagocytosis of Candida. The zona pullucida appears to be an effective barrier to yeast, at least over the time span studied. The observations are consistent with the hypothesis of an initial attachment of yeast via a surface component to oocyte microvilli followed by phagocytic uptake into an endosome. There is no compelling evidence of lysosomal degradation of the yeast over the time course of this study; however, the oocytes appear to undergo some degenerative changes at long incubation times.     

Further observations on Eimeria dolichotis, a coccidium of the Patagonian

In three Patagonian cavies ( Dolichotis Patagonia ) which died in Dutch zoological gardens, coccidia were found. They were determined as Eimeria dolichotis (Morini Boero & Rodriguez, 1955). Cross-infection experiments with guinea-pigs exclude the identity with Eimenc cmvimt .