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S D Stranock

Publications and source records attributed to S D Stranock.

9 recordsLinked to original sources
PubMed1976

Fine structural observations on oocyte development in monogeneans.

The ultrastructural changes accompanying oocyte differentiation in the ovaries of the monogeneans, Diclidophora merlangi, Diplozoon paradoxum and Calicotyle kröyeri have been described. In each case, oogenesis in the ovary proceeds as far as meiotic prophase in the primary oocyte. A three-stage sequence of development based on oocyte morphology is proposed: (1) Oogonia and early, immature primary oocytes are typically undifferentiated, with chromatin-laden nuclei occupying most of the cell volume. The cytoplasm contains small clumps of mitochondria and unattached ribosomal aggregates. There is evidence of mitosis and, in later stages, meiotic prophase is indicated by the appearance of nuclear synaptonemal complexes. (2) Maturing primary oocytes are characterized by increased nucleolar volume associated with the production of RNA for export to the cytoplasm. An organized GER and Golgi apparatus are established and involved in the synthesis and packaging of membrane-limited cortical granules. Annulate lamellae and nucleolus-like bodies appear in the cytoplasm and, with development, the cells increase in size and, peripherally, become interdigitated. (3) Mature primary oocytes represent a resting phase when cellular activity is minimal. Golgi disappear and the ER fragments or becomes reduced in dimensions. Mitochondria and free ribosomes are numerous and cortical granules move to the cell periphery. The cells separate and, when mature, are released from the ovary. There are minor species differences in oocyte ultrastructure and development.

Animals↗
PubMedDate not supplied

Ultrastructure of the muscle spindle in dystrophia myotonica. I. The intrafusal muscle fibres.

The abnormal intrafusal muscle fibres of four spindles located in extensor indicis biopsies from two patients with dystrophia myotonica have been examined by electron microscopy. In all cases, the fibres had undergone severe longitudinal fragmentation in their equatorial, proximal-polar and mid-polar zones. It was not possible to differentiate the fibres into nuclear bag and nuclear chain types. Many of the fragments were arranged in clusters, each cluster being bounded by a single basement membrane. Numerous partially divided fibres were seen in mid-polar sections, and a morphological picture of the fragmentation process has been presented. The ultrastructural appearance of individual fibre fragments ranged from normality through to severe atrophy. Intrafusal satellite cells showed an increase in numbers, presumably in response to the pathological processes affecting the muscle fibres. The nature of this response is discussed.

Cell Division↗
PubMedDate not supplied

Ultrastructure of the muscle spindle in dystrophia myotonica. II. The sensory and motor nerve terminals.

The normal pattern of innervation was lost in the four dystrophia myotonica muscle spindles examined. There had been a proliferation of both sensory and motor nerve terminals, and many endings showed varying degrees of structural abnormality. The changes seen in the sensory nerve endings were an incomplete contact relationship between the terminal and the muscle fibre, the association of Schwann cell processes with the nerve ending, abnormal shape of the terminal, multiple sensory endings, and changes in the ultrastructural organization of the terminal axoplasm. Remnants of degenerated sensory terminals, and isolated sensory endings were also seen. Motor nerve terminals varied in size and shape. In general, they contained a normal complement of vesicles and mitochondria. Junctional folding was often absent or simplified, and sarcoplasmic specialization was, at the most, rudimentary. The relationship between these changes and intrafusal muscle fibre fragmentation is discussed.

Humans↗