Biology Reference
In-Depth Information
Fig. 5.7 Sperm centrosome TS and LS (TEM). The proximal centriole (PC) is hidden in a 'black
box' beneath the basal plate and flanked by nine segmented columns. It shows the typical '9 ? 0'
structure of microtubule (MT) triplets. Note disorganized MTs of distal centriole (DC) and
centriolar adjunct of PC (right) x65,000 (Sathananthan et al.
1996
)
Fig. 5.8 Spermiogenesis and centrioles: The sperm neck region contains the proximal and distal
centrioles. The latter gives rise to the axoneme and becomes a vestige in mature sperm, while the
former persists as the functional centriole that is passed on to the embryo. Both are hidden in a
''black box'' composed of segmented columns, capitulum, and basal plate (Courtesy Prof. David
deKretser, 1996)
The segmented columns show a complex structure in cross-sections of the neck
region, where the centriolar adjunct (CA) extends laterally from the PC (Figs.
5.7
,
5.13
). The CA is a tuft of MTs that shows a disorganized triplet structure and may
represent an attempt to form an axoneme by the PC (de Kretser and Kerr
1994
).
