List of abbreviations
of micros-
specialist terms
explained in
English +

Every attempt was made to provide correct information and labelling, however any liability for eventual errors or incompleteness is rejected!

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Dr. med.
H. Jastrow

of use
Overview nuclear membrane (Nucleolemma, Membrana nuclearis):
Pages with explanations are linked to the text below the images if available! (Labelling is in German)
inner + outer nuclear membrane,
perinuclear space (rat)
nucleus + pores
jejunum (rat)
nuclear lamina and membranes
Schwann's cell (rat)
dilated nuclear membrane
with 2 pores (rat)
stereo image of nuclear membrane
+ pore, inner hair cell (guinea pig)
nuclear lamina & mem-
brane skin (human)
nuclear membrane during
spermiogenesis (rat)
bleb: dilated nuclear membrane
fibroblast of human placenta 
bleb of a myoepithelial
cell parotid gland (rat)
nuclear membrane of a
pneumocte type 2, lung (rat)
nuclear membrane + pores of 
an ovum, ovary (rat)
The nuclear membrane (Nucleolemma; Terminologia histologica: Membrana nuclearis) is the border between the nucleus and the cytoplasm. It has an outer unit membrane (thickness ~ 7 nm; phospholipid double layer) with attached ribosomes followed by the perinuclear space wich is 20 - 100 nm in width and an inner elementary membrane lacking ribosomes. The nuclear lamina is directly attached to the inner nuclear membrane and responsible for nuclear stability. It consists of the interconnected intermediate filaments Lamin A and C, which are attached to a Lamin-B receptor protein belonging to the inner nuclear membrane.
The nuclear membrane originates from rough endoplasmic reticulum (RER) which can be seen in the telophase of a mitosis when it is newly synthetised. The nuclear membrane decays with the transition of the prophase to the metaphase in mitosis forming small membrane tubes or vesicles that correspond to RER. Under normal conditions (in interphase) sometimes a direct transition from RER to the nuclear membrane is visible whereby the perinuclear space is directly continuing into the interior of the RER and the outer nuclear membrane, which has attached ribosomes, is in continuity with RER membranes.  In some cases considerable widenings of the outer nuclear membrane appear which are called blebs (see image above).
Ring-like connections between the inner and the outer nuclear membrane exist only at the disk-like nuclear pores. Entry or exit of substances to the nucleus can only occur at these locations. Very electron-dense material is directly attached to the outer nuclear membrane which later is involved in formation of the acrosome during spermiogenesis in testis.

--> nucleus, nuclear pore, karyoplasm, euchromatine, heterochromatine, nucleolus
--> Electron microscopic atlas Overview
--> Homepage of the workshop

Images, page & copyright H. Jastrow.