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Biomedical subjects

B Baccetti

Publications and source records attributed to B Baccetti.

At least 73 records · Page 4Linked to original sources
PubMed1983

The Sertoli cell in lizards.

Sertoli cells of lizards are characterized by variable size, abundant smooth and rough endoplasmic reticulum, multivesicular bodies, lipid vacuoles probably related to the spermatogenic cycle, and mitochondria of normal size. The cytoskeleton contains actin, particularly abundant in the cell periphery, vimentin all around the nucleus and throughout the rest of the cytoplasm. Moreover, microtubules are distributed in the cell periphery. The junctional complexes demonstrate the presence of a very efficient blood-testis barrier, containing tight, gap, tight-gap, septate-like, desmosome-like, and "Sertoli-Sertoli" junctions. In the last, the actin layer interposed between the plasma membrane and the subsurface cistern is absent. The desmosome-like junctions are surrounded by 7-nm filaments and not by intermediate filaments.

Actins↗
PubMed1983

Structure and motility of the 9 + 0 flagellum of eel spermatozoa.

Scanning and electron microscopic study of the spermatozoon of the eel, Anguilla anguilla, has shown that the large oblong head is attached eccentrically by one end to the basal end of the true flagellum and contains a pseudoflagellum that splits into two groups of tubules as it passes around the nucleus. The 9+0 axoneme of the true flagellum lacks outer dynein arms and the radial spoke complex. The movement of Anguilla sperm is characterized by rapid forward progression that is the result of left-handed helicoidal waves propagated distally at a beat frequency at 21 degrees of about 95 Hz. Thus, these sperm flagella, although reduced in structure, propagate three dimensional rather than planar waves as in sea urchin sperm flagella, and beat at a frequency which so far as we know is the highest observed in eukaryotic flagella.

Anguilla↗
PubMed1982

The evolution of the sperm tail.

In this paper the evolution of the sperm tail is discussed. The primitive motile apparatus is assumed to be a conventional '9 + 2' axoneme which persists in all aquatic phyla having external fertilisation. Where internal fertilisation has evolved in association with terrestrial life, the sperm tail has a '9 + 9 + 2' pattern: it has acquired new accessory proteins and has become enormously elongated. A subsequent trend is towards diminished motility, owing perhaps to the excessive development of skeletal structures and sophisticated copulatory organs. This is marked by unusual axoneme patterns and a lack of dynein arms. Aflagellate spermatozoa seem to represent a high evolutionary level. Finally, it appears that in the sperm of some groups motility has been regained. However, the axoneme never reappears: motility is produced instead by the spermatid manchette or an actin system.

Animals↗
PubMed1981

Human dynein and sperm pathology.

Human spermatozoa with normal structure and with different axonemal deficiencies (absence of axoneme, of arms, or of central structures) were studied by electron microscopy, SDS-polyacrylamide gel electrophoresis, and ATPase activity measurements. Normal human sperm possess a complement of high molecular weight polypeptides with an electrophoretic migration similar to that of sea urchin and other mammalian sperm dyneins. Human high molecular weight bands are numbered one to four in order of increasing of electrophoretic mobility; all of them are absent in spermatozoa that lack axoneme. The absence of doublet arms, coincides with the absence of bands 2, 3, and 4; the absence of central structures coincides with a reduction in intensity of band 2. In the latter two abnormal conditions, band 1 has an increased intensity. The data are tentatively interpreted by attributing the polypeptides forming bands 3 and 4 to the arm structure, whereas band 2 is supposed to contain a mixture of polypeptides localized in the arms and in the central structures; these abnormal sperm contain modified polypeptides which gather in band 1. Histochemical ATPase stainings indicate that this enzyme is localized mainly in the doublet arms and, to a minor extent, in the central structures.

Adenosine Triphosphatases↗
PubMed1981

Different axoneme patterns in cilia and flagella of the same animal.

In eel fish ependymal cilia have a '9 + 2' axoneme with doublets bearing two dynein arms, while sperm flagella have a '9 + 0' axoneme, with doublets bearing only the row of inner arms. On this basis, the possibility that in the same animal a different genetic system regulates the flagellar and ciliary axoneme assembly is discussed.

Animals↗
PubMed1981

Submicroscopic localization of human sperm antibodies.

In this paper the localization of three antisperm sera obtained from vasectomized men has been studied at submicroscopic level. The sera have been demonstrated to react respectively with the acrosin, the columns and the dense postacrosomal sheath, that appear to be made up of specific proteins, absent from other sperm regions. No serum has been found active against the more widely distributed proteins tubulin, dynein or actin.

Acrosome↗
PubMed1981

Angelo Bairati.

Explore the source record for details and available documents.

Cell Biology↗
PubMed1981

Scanning electron microscopy and human sperm pathology.

This paper has been carried out in order to inquire whether some of the best known human malformations can be recognized by scanning electron microscopy. The SEM appearance of "straight tailed", "empty tailed", "short tailed", "round headed", "double", "old" human spermatozoa is described, 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, 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 shape 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.

Electrophoresis↗
PubMed1979

The dynein electrophoretic bands in axonemes naturally lacking the inner or the outer arm.

Two unconventional sperm models (all motile) have been studied. The first one has only the outer arm on the doublets (the gall midge, Diplolaboncus); the second one, has only a well-developed inner arm (the eel, Anguilla). Both are devoid of central tubules and radial spokes. The gall midge sperm yields a single electrophoretic band migrating similarly to the sea urchin dynein band A; a major high-molecular-weight band is obtained from eel sperm which co-migrates with the sea urchin dynein band B. The present picture is consistent with the localization of dynein in the axoneme--namely, of an A-like band in the outer arm, and of the B band in the inner arm. Moreover, the D band is present only in the eel, where gamma-links are present. ATPase activity was localized histochemically and found to be associated with both inner and outer arms, as well as with the gamma-links.

Adenosine Triphosphatases↗
PubMed1979

"9 + 0" immotile spermatozoa in an infertile man.

In this paper the peculiar case of an infertile man, possessing only normally shaped, but stiff and immotile spermatozoa is described. All the sperm are conventionally structured, with the constant characteristic of the absence of central tubules and projections forming the so-called central sheath. Electrophoretic analysis of the high molecular weight polypeptide chains attributed to dyneins shows the constant absence of one chain. The importance of the central structure, usually belonging to the "9 + 2" model spermatozoa, and the possible localization of a dynein chain in this region are discussed.

Adult↗
PubMed1978

The spermatozoon of arthropoda. XXX. The multiflagellate spermatozoon in the termite Mastotermes darwiniensis.

In this paper the spermatozoon of the termite Mastotermes darwiniensis is described. It is the first example of a multiflagellate sperm cell in animals. The sperm consists of a conical head and 100 flagella. Other remarkable features of this sperm cell are the absence of an acrosome, the presence of centrioles containing doublet microtubules instead of triplets, and the presence of axonemes devoid of central tubules and with doublets bearing only one arm. The flagella are feebly motile.

Animals↗
PubMed1977

The spermatozoon of onychophorans. 2. Peripatoides leuckarti.

The spermatozoon of the Onychophoran Peripatoides leuckarti is described and compared with that of Peripatopsis previously investigated. The general shape of the cell is the same, with persisting typical characteristic of a manchette and of nine accessory tubules surrounding the axoneme. There is a difference in the mitochondrial derivatives, which are two and partially located in a nuclear posterior concavity. But the most significant finding is the presence of a thin, flat acrosome surrounding the nucleus, which is absent from the other species. The presence of the acrosome is related to the existence in Peripatoides of big eggs, which are absent in Peripatopsis.

Acrosome↗
PubMed1977

Protein of insect sperm mitochondrial crystals. Crystallomitin.

Mitochondrial derivatives of insect sperm usually contain a crystalline protein that shows a 45-nm main period, made up of 20-nm subperiods, determined by the coiling of filament bundles. Filaments are 2 nm thick and have a globular appearance. The crystals contain two main polypeptides, 52,000 and 55,000 daltons. These polypeptides are closely related, contain a high percentage of proline, and are insoluble in sodium dodecyl sulfate due to disulfide cross links. We suggest for this class of protein the name crystallomitin.

Amino Acids↗