Analytical Cytology: Methods for Studying Cellular Form and Function

By Robert C. Mellors | Go to book overview

structure was, in both cases, enhanced by the use of acid fixatives and by the removal of the embedding, since in sections fixed in buffered osmic acid only a finely granular material is revealed in the nucleus. Thus, as mentioned by Sjöstrand with respect to the cytoplasm (163), little can yet be concluded in this area of the cell.


NUCLEAR MEMBRANE

The nuclear membrane has been shown to possess a very interesting double structure in many cell types. In oöcyte nuclei which were simply spread thinly upon grids, the inner membrane was shown to be continuous, while the outer one consisted of fine pores (34). A similar structure exists in Amoeba proteus. In this case, the continuous membrane is the outer membrane, while the inner one is porous (78). Bairati and Lehmann (6) describe the pores as 1,200 A in diameter with 1,500-A spaces between them, while the continuous layer consists of small, densely packed globular particles. The inner membrane is very resistant to mechanical action and to different fixing fluids, and it contains few lipoids. In sections of these cells, Harris and James; (78) describe the outer layer as 1,000 A thick and the inner layer as 2,000 A thick. Their measurement for the space in between pore centers is 1,200 A with a pore diameter of 800 A.

The membranes of nuclei of animal tissue cells have also been shown to be double, although of much finer dimensions than those described above, while no finer structure within the membranes has yet been revealed. The doubleness was first shown in neuronal nuclei by Hartman (79). Such doubleness has now been observed in kidney cells (163) and in all cells under our investigation. Sjöstrand (163) was able to measure the total thickness of a nuclear membrane in the kidney tubular cells as 230 A units with a distance between the centers of the single membranes as 160 A units. This makes the calculated thickness of a single membrane as 60 A units and the height of the space in between 100 A units. Although such accurate measurements have not been made on nuclei of other cell types, they all appear to be of the same order of thickness (157).


Summary

It has been the purpose of this article to demonstrate the manner in which electron-microscopic studies of biological tissues may be made, the information which such studies have yielded to date, and their potential contributions in future years. It was necessary to spend most of the first decade of the availability of the electron microscope in developing methods to prepare biological specimens sufficiently dry, suffi

-6/62-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
Analytical Cytology: Methods for Studying Cellular Form and Function
Settings

Settings

Typeface
Text size Smaller Larger
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen
/ 32

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.