Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Spermatogenesis in Blasia pusilla: From Young Antheridium through Mature Spermatozoid

Karen S. Renzaglia and Jeffrey G. Duckett
The Bryologist
Vol. 90, No. 4 (Winter, 1987), pp. 419-449
DOI: 10.2307/3243109
Stable URL: http://www.jstor.org/stable/3243109
Page Count: 31
  • Read Online (Free)
  • Download ($10.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Spermatogenesis in Blasia pusilla: From Young Antheridium through Mature Spermatozoid
Preview not available

Abstract

An ultrastructural analysis of spermatogenesis in the liverwort Blasia pusilla was undertaken to consider, in detail, the development of the spermatogenous tissue, the origin and ontogeny of the blepharoplast, organelle metamorphosis and repositioning, and the cytoplasmic deletion process. Mechanisms of polarity, and spatial and temporal changes in cellular components are discussed. In spermatogenesis of Blasia, the reduction in plastid number occurs early in the development of the antheridium. A biplastidic condition is maintained for several generations. In the final divisions of the antheridium, the cells are monoplastidic. The cell plates are oriented perpendicular to the long axes of these cells until the ultimate mitosis in the spermatid mother cell. The centrosomes are produced in this cell and become positioned in diagonally opposed corners of the cell where the mitotic spindles form. The plane of division in the androcyte mother cell is, therefore, diagonal and produces a pair of spermatids in which the organelle placement is established for the ultimate spiralled condition of the gamete. In the nascent spermatid the single centrosome splits into two centrioles which reorient in a side-by-side location. The basal bodies initially grow anteriorly, along with the MLS, producing the proximal extensions typical of liverwort spermatids. The ABB becomes fixed in position and is at its maximum length before the PBB. Posterior growth of the MLS continues as the PBB increases in length and moves rearward to establish the basal body stagger of the mid-stage gamete. The LS ceases growth when the PBB is at its maximum length. Following this, posterior growth of the spline continues and is synchronized with the growth of the flagellar axonemes. The fully developed spline forms the backbone upon which nuclear shaping occurs. Plastid migration and elongation, in contrast, is synchronized with spline growth. Final streamlining of the spermatozoid involves the elongation and condensation of all organelles, and the elimination of over 90% of the cytoplasm. The mature gamete coils for nearly two revolutions and contains two mitochondria, an elongated nucleus, a single plastid, and the locomotory apparatus.

Page Thumbnails

  • Thumbnail: Page 
[419]
    [419]
  • Thumbnail: Page 
420
    420
  • Thumbnail: Page 
421
    421
  • Thumbnail: Page 
422
    422
  • Thumbnail: Page 
423
    423
  • Thumbnail: Page 
424
    424
  • Thumbnail: Page 
425
    425
  • Thumbnail: Page 
426
    426
  • Thumbnail: Page 
427
    427
  • Thumbnail: Page 
428
    428
  • Thumbnail: Page 
429
    429
  • Thumbnail: Page 
430
    430
  • Thumbnail: Page 
431
    431
  • Thumbnail: Page 
432
    432
  • Thumbnail: Page 
433
    433
  • Thumbnail: Page 
434
    434
  • Thumbnail: Page 
435
    435
  • Thumbnail: Page 
436
    436
  • Thumbnail: Page 
437
    437
  • Thumbnail: Page 
438
    438
  • Thumbnail: Page 
439
    439
  • Thumbnail: Page 
440
    440
  • Thumbnail: Page 
441
    441
  • Thumbnail: Page 
442
    442
  • Thumbnail: Page 
443
    443
  • Thumbnail: Page 
444
    444
  • Thumbnail: Page 
445
    445
  • Thumbnail: Page 
446
    446
  • Thumbnail: Page 
447
    447
  • Thumbnail: Page 
448
    448
  • Thumbnail: Page 
449
    449