摘要:

AbstractThe acrosomes of mammalian spermatozoa contain a proteolytic enzyme which may be of importance for fertilization. The release and activity of the enzyme can be visualized directly when the spermatozoa are applied to fixed gelatin membranes. The purpose of this study was to determine the pattern of enzyme release from the spermatozoa of a variety of mammalian species. Thin, transparent membranes of pure gelatin were prepared on microscope slides and fixed in glutaraldehyde. Spermatozoa were applied to the membranes and their proteolytic behavior observed under dark‐medium phase objectives at 37°C. In all the species examined (rabbit, bull, hamster, rat, guinea pig and man) extensive depolymerization of the gelatin substrate occurred around the sperm heads. With the exception of human spermatozoa, the onset of proteolysis was clearly identified with the posterior half of the acrosome. In the case of human spermatozoa, no such distinction could be made. It is suggested that the proteolytic enzyme of most mammalian spermatozoa is located in the posterior segment of the acroso

ISSN:0002-9106    

DOI:10.1002/aja.1001340202

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe pituitary gland of the musk shrew,Suncus murinusL. was studied with special reference to the cytology of the adenohypophysis. In addition to the agranular cells (chromophobes), seven morphologically and tinctorially distinct chromophilic cell types (four mucoid and three acidophilic) were observed in the pars anterior. These cells have been tentatively named as types one to seven. On the basis of their morphology, topography and staining reactions, cells of types one to six were compared, respectively, with the TSH, FSH, ICSH (LH), LTH (prolactin), STH and ACTH cells of other mammals. The identity of type 7 cells could not be determined. Although mucoid cells (types 1, 2) are more concentrated in the rostroventral region of the pars anterior, a definite “zona tuberalis” seems to be lacking.Since the musk shrew is not a seasonal breeder, the gonadotropic cells (types 2, 3) of the adenohypophysis do not seem to fluctuate in structure during the different times of the year. However, conspicuous hypertrophy, hyperplasia and intense secretory activity of type 4 cells during pregnancy and lactation reinforces the postulation that these cells are lactotropic in function.Follicular cysts and colloid in the residual cleft were observed in a few instances. Their possible origin and significance are discus

ISSN:0002-9106    

DOI:10.1002/aja.1001340203

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

年代:1972

数据来源: WILEY

摘要:

AbstractMalformation of the heart and great vessels in a human embryo of 23‐mm crown‐rump length (Horizon XXII) is described on the basis of reconstruction of serial sections. A type I truncus arteriosus malformation with right aortic arch and absent ductus arteriosus was present. The left ventricle was anterior and lateral to the right. It is postulated that the malposition of the ventricles produced an abnormal relationship of the outflow blood streams which led to the truncus arteriosus malformat

ISSN:0002-9106    

DOI:10.1002/aja.1001340204

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe fine structure of mitosis in myocardial cells possessing myofibrils from embryonic chick hearts (4.5–6 days incubation age) is described. In these cells during prophase, chromosomes appear, but the nuclear membrane, Golgi complexes, and Z bands mostly disappear. In metaphase, lipid droplets and large quantities of membranous cisternae localize around the centrioles, while sarcomeric lengths of myofibrils (largely without Z bands) are found disoriented in the periphery, mainly in the polar zones. In anaphase the cisternae collect near the chromosomes, as reconstruction of the nuclear membrane commences. An intact nuclear envelope and well‐formed Golgi complexes characterize telophase, but Z bands still are not present. During all of the mitotic stages, junctional complexes between dividing cells and adjacent resting cells pers

ISSN:0002-9106    

DOI:10.1002/aja.1001340205

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

年代:1972

数据来源: WILEY

摘要:

AbstractOsmiophilia of the cellular elements of the alveoli and bronchioles was investigated using the new technique of second osmication with a solution containing a mixture of osmium tetroxide and ethanol. Previously this method was used to reveal osmiophilic periodic lamellae of synthetic dipalmitoyl lecithin and the surface film of the acellular alveolar lining layer of the mammalian lung in thin sections.In the present experiments, much of the osmiophilic content of inclusions in type II epithelial cells became visible only after second osmication with osmium‐ethanol but was not visible with the initial osmium tetroxide fixation. The osmiophilic content of the inclusions showed 42 Å periodicity. These results are in accord with those obtained in the study of dipalmitoyl lecithin and the surface film, suggesting that the inclusions are the precursors of the pulmonary surfactant.Several new observations were made with this technique. These include osmiophilic lamellae within Golgi saccules, within the multivesicular bodies of type II cells, in the vesicles of type I epithelial cells, and in the basement membranes of epithelial cells. These observations are consistent with the idea that the Golgi apparatus and multivesicular bodies are closely related to the production of surfactant and that the surfactant may be disposed of by type I epithelial cells after engulfment by pinocytosis. Thereafter, the surfactant may eventually be cleared through the lymphatics.Clara cell granules behaved differently and were thought to be an unlikely site for the synthesis of the pulmonary surfacta

ISSN:0002-9106    

DOI:10.1002/aja.1001340206

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

年代:1972

数据来源: WILEY

摘要:

AbstractElectron microscopic examinations have been made on 32 early human placentas, seven of which ranged from 7 to 11 weeks menstrual age. In avascular villi, well developed basal laminae separate the trophoblast from their connective tissue cores. At such stages, only undifferentiated mesenchymal cells occur in the stroma. Vessels develop by attachment of two or more of the mesenchymal cells to each other by localized desmosomal contacts, thus forming a real or potential capillary lumen between their apposed plasma membranes. Other mesenchymal cells approach these primitive tubes, enclasp them as pericytes, and thrust processes between adjacent endothelial cells at their attachment points. The capillary enlarges, therefore, by incorporation of mesenchymal pericytes between adjacent endothelia. Mitoses occur in the pericytes but not in early endothelial cells. Hofbauer cells differentiate in the stroma concomitantly with the appearance of capillaries.

ISSN:0002-9106    

DOI:10.1002/aja.1001340207

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe fine structure of testicular interstitial cells from mice submitted to different experimental conditions is described. Following treatment with methallibure (I.C.I. 33,828; 1‐α‐methylallylthiocarbamoyl‐2‐methylthiocarbamoylhydrazine), a selective inhibitor of hypophyseal gonadotropic activity, interstitial cells acquire a quiescent appearance characterized by: (1) accentuated segregation of agranular endoplasmic reticulum from other cytoplasmic organelles and inclusions, (2) increased depots of lipid droplets. A single injection of interstitial‐cell‐stimulating hormone (ICSH or LH) induces prominent changes in the ultrastructure and distribution of cell inclusions and organelles that are seemingly related to augmented secretory activity. The cell surface shows a striking development of cytoplasmic processes that interdigitate with similar processes from adjacent cells. Intercellular spaces form a system of interfacial channels providing a direct connection of the interstitial cell surface with blood vessels and the myoid layer of seminiferous tubules. Gonadotropic stimulation causes an increased number of free ribosomes and expansion of the Golgi complex and rough endoplasmic reticulum. There is a marked depletion of lipid droplets and formation of lipofus

ISSN:0002-9106    

DOI:10.1002/aja.1001340208

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

年代:1972

数据来源: WILEY

摘要:

AbstractSerum iron transfer from mother to fetus was measured in near‐term pregnant females from 16 species representing 15 families and 7 orders of eutherian mammals. The amount of transfer at 2 hr was 5% or greater in species with hemochorial placentation and less than 0.1% at 3 hr in species with epitheliochorial or endotheliochorial placentatio

ISSN:0002-9106    

DOI:10.1002/aja.1001340209

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

年代:1972

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001340201

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

年代:1972

数据来源: WILEY