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Biomedical subjects

R Czaker

Publications and source records attributed to R Czaker.

21 records · Page 2Linked to original sources

Multiple malformation of bovine spermatozoa with special reference to their lightmicroscopic fluorescing pattern and electron-microscopic structure.

The light microscopic examinations of sperm samples from a sterile Fleckvieh-bull stained by the AT specific fluorochrome Hoechst 33258 showed beneath the constantly occurring paraxial tail numerous other malformations, which appeared under the electron microscope as multiple defects of essential cell organelles: defects of the acrosome as irregular thickening or forming of overturned folds "knobbed acrosome", sometimes with vesicles and inclusions inside, partial separation of the acrosome lamina from the nucleus. The defects of the nucleus were present as double-headed sperms, macro- and microcephalic forms besides bizarre shaped heads with gigantic cavities, often filled with membranes, cytoplasm and canaliculi even as heads with ridges which extended from the base to the apex. The main tail defect was a paraxial inserted tail, sometimes coiled, folded or bent down and combined with duplication or even multiplication of the tail with one or two implantation fossae. This multiplication was followed by extensive disturbances of the tail elements as lack or excessive numbers up to the isolation of tubules, fibers and mitochondria. Often there was no contact between tail and implantation fossa. Another defect was the existence of voluminous cytoplasmic droplets covering not only great parts of the tail but also the total head which included "arch like double membranes" and up to 15 tail segments. The persisting cytoplasmic droplet even as the generally occurring paraxial inserted tail are discussed in connexion with the existing hormonal imbalance as probably genetic damage leading to extensive defects during spermiogenesis.

Acrosome↗

Ultrastructural observations on nucleolar changes during mouse spermiogenesis.

When applying a new silver staining technique on developing mouse spermatids, it could be shown that strong argyrophilia in the "padlock" like nucleolus of very early spermatids is confined to its fibrillar and granular component, whereas the fibrillar centre is devoid of silver. During further steps the granular component disappears together with the fibrillar centre. The last remaining nucleolar part, the silver positive fibrillar component disintegrates at the beginning of nuclear elongation. Instead of it clusters of coiled fibers bordered with granules of approximately 40-60 nm in diameter, both silver positive, appear in the nucleoplasm. As chromatin condensation proceeds, these silver positive structures, now intimately attached to the centrally occurring focus of condensing chromatin decrease more and more in size and density. In later stages accumulations of silver positive material will appear in the posterior region of the nucleus, will leave it, and stays as silver positive "juxtanuclear body" in the nuclear pocket formed by the redundant nuclear envelope. As spermatid development continues, the "juxtanuclear body" disappears together with the nuclear pocket. The small silver positive fibrous clusters disintegrate too so that the mature sperm only contains the space in which they formerly existed, now called "nuclear vacuole". A possible connection between silver staining pattern and RNA synthesis is discussed.

Animals↗

On the origin of nuclear vacuoles in spermatozoa a fine structural and cytochemical study in mice.

Morphological and cytochemical changes in nucleoli of spermatids of the mouse during spermiogenesis were examined. Thus, it could be shown that the nucleolar derivatives of the elongation-phase, clusters of coiled fibers that are bordered with spheroidal bodies, show comparable chemical properties as the precursor structure, the fibrillar component, which is known for its transcriptional activity. With progressing development, these nucleolar derivatives continually decrease in size and density, preserving their chemical properties. They persist far beyond into the maturation-phase and will decrease at the time chromatin condensation appears finished. There only remain the spaces in which they formerly existed, now called nuclear vacuoles. A possible function of nuclear vacuoles with respect to chromatin decondensation during the process of fertilization is mentioned.

Animals↗