SPERMIOGENESIS AND SPERMATOZOON OF ECHINOSTOMA-CAPRONI (PLATYHELMINTHES, DIGENEA) - TRANSMISSION AND SCANNING ELECTRON-MICROSCOPY, AND TUBULIN IMMUNOCYTOCHEMISTRY
C. Iomini et Jl. Justine, SPERMIOGENESIS AND SPERMATOZOON OF ECHINOSTOMA-CAPRONI (PLATYHELMINTHES, DIGENEA) - TRANSMISSION AND SCANNING ELECTRON-MICROSCOPY, AND TUBULIN IMMUNOCYTOCHEMISTRY, Tissue & cell, 29(1), 1997, pp. 107-118
Spermiogenesis and the spermatozoon of Echinostoma caproni (from exper
imentally infested laboratory mice) were investigated by several metho
ds. Transmission electron microscopy shows that spermiogenesis consist
s of a proximo-distal fusion of three processes followed by elongation
of the spermatid. Scanning electron microscopy shows that the spermat
ozoon is a filiform cell, 235 mu m in length, with a cylindrical anter
ior extremity and a broader posterior extremity. Epifluorescence micro
scopy, including immunocytochemistry of tubulin and labelling of nucle
us with specific dyes, has provided valuable additional information. M
igration of the nuclei from the common cytoplasmic mass of spermatids
to the distal part of the elongating spermatids is visualized, and cen
trioles demonstrated in the proximal, anterior region, and the nucleus
in the distal, posterior region of the spermatozoon. One axoneme has
a distal extremity which in the mature spermatozoon extends 30 mu m mo
re distally than the other, with the result that the posterior part of
the spermatozoon contains a single axoneme and the nucleus. Immunocyt
ochemistry experiments show that a region, 15 mu m in length, not labe
lled by the anti-tubulin antibodies with certain fixation-permeabiliza
tion procedures, corresponds to a region which, by transmission electr
on microscopy, shows external ornamentation on the membrane. This regi
on has a bilaterally asymmetric pattern (in TEM), forms angles or coil
s according to the fixation used, and marks the boundary between two d
istinct patterns of movement. Spermiogenesis and the spermatozoon in E
. caproni correspond to the general pattern found in the digeneans, wi
th the exception of this asymmetric region. It is emphasized that the
use of various methods provides a better understanding of sperm struct
ure than transmission electron microscopy alone, particularly in the c
ase of long, filiform spermatozoa.