Biology Reference
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S
A
S
S
S
B
M
S
S
MMM
M
M
Body size/age
Body size/age
Fig. 53. Schematic illustration of structural sex differentiation levels as function of body size/
age (A) protogynic and (B) protoandric hermaphrodites. S = Spawning, M = Milting, ↑ = size/
age at sexual maturity, ↓ = size/age at sex change
VD
FOW
FOW
VD
FOW
Fig. 54. Transverse section of testis of (A) Lethrinus rubrioperculatus (from Ebisawa, 1997) (B)
Calotomus japonicus (from Kusen and Nakazono, 1991) and (C) Thalassoma lutescens (from
Shibuno et al., 1994). Note the presence of former ovarian wall and former ovarian canal in
these testes
Using nuclear and cytoplasmic diameters and their location in the
germinal epithelium of the protandric Sparus aurata, Chaves-Pozo et al.
(2005) distinguished Spermatogonial Stem Cells (SSCs) from Primary
Spermatogonial Cells (PGCs). Both Sertoli Cells (SCs), SSCs and PSCs
proliferate by successive spermatogenetic waves throughout the
reproductive cycle at the reproductive stage-dependent rate. During post
spawning, the resumption of proliferation, the occurrence of apoptotic
spermatogonia, and the phagocytosis of nonshed spermatozoa by SCs
lead to a reorganization of both the germinal compartment and the
interstitial tissue. But most unexpectedly, both oogonia and oocytes are
also proliferated, suggesting the operation of a complex mechanism in the
regulation of gonocyte proliferation in protoandric fi shes.
The foregone descriptions have shown that there is wide structural
diversity in the gonads and possible gonadal ducts of sex changing
hermaphrodites. Yet there seems a commonality between gonochores
and hermaphrodites, and uniformity in the endocrine mechanism which
 
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