Details:

Alternative Title:
J Cell Biol
Description:
The ultrastructure of spindle formation during the first meiotic division in oocytes of the Strepsipteran insect Xenos peckii Kirby (Acroschismus wheeleri Pierce) was examined in serial thick (0.25-micron) and thin sections. During late prophase the nuclear envelope became extremely convoluted and fenestrated. At this time vesicular and tubular membrane elements permeated the nucleoplasm and formed a thin fusiform sheath, 5-7 micron in length, around each of the randomly oriented and condensing tetrads. These membrane elements appeared to arise from the nuclear envelope and/or in association with annulate lamellae in the nuclear region. All of the individual tetrads and their associated fusiform sheaths became aligned within the nucleus subsequent to the breakdown of the nuclear envelope. Microtubules (MTs) were found associated with membranes of the meiotic apparatus only after the nuclear envelope had broken down. Kinetochores, with associated MTs, were first recognizable as electron-opaque patches on the chromosomes at this time. The fully formed metaphase arrested Xenos oocyte meiotic apparatus contained an abundance of membranes and had diffuse poles that lacked distinct polar MT organizing centers. From these observations we conclude that the apparent individual chromosomal spindles--seen in the light microscope to form around each Xenos tetrad during "intranuclear prometaphase" (Hughes-Schrader, S., 1924, J. Morphol. 39:157-197)--actually form during late prophase, lack MTs, and are therefore not complete miniature bipolar spindles, as had been commonly assumed. Thus, the unique mode of spindle formation in Xenos oocytes cannot be used to support the hypothesis that chromosomes (kinetochores) induce the polymerization of their associated MTs. Our observation that MTs appeared in association with and parallel to tubular membrane components of the Xenos meiotic apparatus after these membranes became oriented with respect to the tetrads, is consistent with the notion that membranes associated with the spindle determine the orientation of spindle MTs and also play a part in regulating their formation.
Subjects:
[+]
Animals Cell Nucleus Female Insects Interphase Intracellular Membranes Meiosis Metaphase Microscopy, Electron Microtubules Nuclear Envelope Oocytes Prophase
Source:
J Cell Biol. 97(4):1144-1155.
Pubmed ID:
6619190
Pubmed Central ID:
PMC2112622
Document Type:
Journal Article
Funding:
PHS 01219/PH/PHPPO CDC HHS/United States
Collection(s):
CDC Public Access
Main Document Checksum:
[+]
urn:sha256:f93e8d8a06cd27a2b45d57b206cd568d9f3984c3a69026996cd3db3e1b884b77
Download URL:
https://stacks.cdc.gov/view/cdc/30797/cdc_30797_DS1.pdf
File Type:

Supporting Files

• 	jc9741144.nxml	txt
  	license.txt	txt

More +