Resum:
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This study describes the morphology of the
sperm cell of Maja brachydactyla, with emphasis on localizing
actin and tubulin. The spermatozoon of M. brachydactyla
is similar in appearance and organization to other
brachyuran spermatozoa. The spermatozoon is a globular
cell composed of a central acrosome, which is surrounded
by a thin layer of cytoplasm and a cup-shaped nucleus
with four radiating lateral arms. The acrosome is a subspheroidal
vesicle composed of three concentric zones surrounded
by a capsule. The acrosome is apically covered by
an operculum. The perforatorium penetrates the center of
the acrosome and has granular material partially composed
of actin. The cytoplasm contains one centriole in
the subacrosomal region. A cytoplasmic ring encircles the
acrosome in the subapical region of the cell and contains
the structures-organelles complex (SO-complex), which is
composed of a membrane system, mitochondria with few
cristae, and microtubules. In the nucleus, slightly condensed
chromatin extends along the lateral arms, in
which no microtubules have been observed. Chromatin
fibers aggregate in certain areas and are often associated
with the SO-complex. During the acrosomal reaction, the
acrosome could provide support for the penetration of the
sperm nucleus, the SO-complex could serve as an anchor
point for chromatin, and the lateral arms could play an
important role triggering the acrosomal reaction, while
slightly decondensed chromatin may be necessary for the
deformation of the nucleus. |