1,721,148 research outputs found
Zoogeographical expeditions of the C.N.R. ship "Minerva" around the small circumsardinian islands: a synthesis.
No full textThe spermatozoon of Arthropoda. VI. Ephemeroptera
No full textIn this work the spermatozoon of Chloëon dipteron (Ephemeroptera) is examined. The three most important features are that (a) the acrosome is very brief; (b) the mitochondrial derivative is represented by a long mitochondrion with transverse cristae and by a crystalline mass enveloped in a separated membrane; (c) the axial filament of the tail lacks the two principal central units and the central sheath, and is therefore, of the 9 + 9 +0 pattern. This type of flagellum has not previously been described. © 1969 Academic Press, Inc
Scanning electron microscopy and human sperm pathology
No full textThis paper has been carried out in order to inquire whether some of the best known human malformations can be recongnized by scanning electron microscopy. The SEM appearance of 'straight tailed', 'empty tailed', 'short tailed', 'round headed', and related to the inner structure. Straight tails and empty tails are quite evident at SEM. These defects are due to severe axonemal defects, related to dynein and tubulin deficiencies: '9+0', 'arm less' and 'axoneme less' spermatozoa are included in this category. Short tails and round heads are still more evident defects, and round heads are still more evident defects, due to complete absence of tail structures or acrosome and easily recognizable at SEM. Double spermatozoa are consistently in patients having abnormally high prolactin level and SEM is obviously sufficient for the diagnosis. Finally, spermatozoa in aged individuals show in SEM a peculiar shapse due to absence of immature stages, reduced cytoplasm, disordered axoneme. It is concluded that SEM examination is a good tool for the identification of most of the best known human sperm abnormalities
Baccetti, B. (ed.), 1987. — Evolutionary biology of orthopteroid insects. Ellis Horwood Series in Entomology and Acarology, E. Horwood Ltd, Chichester
No full textVoisin Jean-François. Baccetti, B. (ed.), 1987. — Evolutionary biology of orthopteroid insects. Ellis Horwood Series in Entomology and Acarology, E. Horwood Ltd, Chichester. In: Bulletin de la Société entomologique de France, volume 93 (1-2), octobre 1988. p. 11
Struttura , funzione e patologia degli spermatozoi umane valutate con metodi submicroscopici
No full textEvaluation of morphometry and related chromosomal abnormalities in human sperm: a FISH study
No full textPATTERN OF BACTERIOCYTE FORMATION IN PERIPLANETA AMERICANA (L.) (BLATTARIA: BLATTIDAE)
No full textIn the embryos of Periplaneta americana CL.) (Blattaria : Blattidae), bacterial symbionts, together with vitellophages, fonn a mycetomic structure inside the deutoplasm; this regresses between the 15th and 16th day after deposition ofthe ootheca. In tms article we describe the migration of bacteria across the wall of the midgut from the mycetorne, and the topographic distribution of pre-bacteriocyte cells. We also Tepori that the pre-bacteriocytes are present only on the lateral surface of the
internaI abdormnal fat bodies. We discuss the possible embryological origin and evolution of these cells, and put forward the hypothesis that pre-bacteriocytes are derived from oenocytes activated to perforro phagocytosis
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