English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Ultrastructural studies on sea urchin eggs (Afzelius, 1957 ; Harris, 1967, 1969; Verhey and Moyer, 1967 ; Bal et al., 1968) have revealed certain cytoplasmic bodies, called heavy bodies, which originate from the egg nucleus. These structures are aggregations of approximately 150 A electron-opaque granules surrounded by annulate lamellae . It has been suggested that heavy bodies are cytoplasmic sites of stored nuclear developmental information . Harris (1967, 1969) has postulated that heavy bodies might be the site of ribosome-bound or inactive messenger RNA. Bal et al . (1968) have suggested that annulate lamellae might contain the information needed for the synthesis of ribosomes ; therefore the heavy bodies would be packets of newly synthesized ribosomes . Other functions postulated for the annulate lamellae which might also involve heavy bodies are storage of materials for the initiation of cleavage furrow formation (Tilney and Marsland, 1969) or for membrane synthesis during embryogenesis (Anderson, 1969) . The postulated functions for heavy bodies have been based entirely on electron microscope observations of their formation and behavior in both the unfertilized and fertilized egg and on Afzelius's (1957) observation of an intense basophilic staining reaction (presumably due to RNA) corresponding to the position of heavy bodies in centrifuged sea urchin eggs . Since heavy bodies have not been isolated from homogenates of sea urchin eggs, no direct biochemical analyses have been conducted . Information concerning the chemical composition of heavy bodies, and especially the presence of RNA, has now been obtained by employing cytochemical techniques and is presented here .

EVIDENCE FOR RNA IN THE HEAVY BODIES OF SEA URCHIN EGGS