AN IMMUNOHISTOCHEMICAL ANALYSIS OF THE ONTOGENY, DISTRIBUTION AND COEXISTENCE OF 12 REGULATORY PEPTIDES AND SEROTONIN IN ENDOCRINE-CELLS AND NERVE-FIBERS OF THE DIGESTIVE-TRACT OF THE TURBOT, SCOPHTHALMUS-MAXIMUS (TELEOSTEI)
M. Reinecke et al., AN IMMUNOHISTOCHEMICAL ANALYSIS OF THE ONTOGENY, DISTRIBUTION AND COEXISTENCE OF 12 REGULATORY PEPTIDES AND SEROTONIN IN ENDOCRINE-CELLS AND NERVE-FIBERS OF THE DIGESTIVE-TRACT OF THE TURBOT, SCOPHTHALMUS-MAXIMUS (TELEOSTEI), Anatomy and embryology, 195(1), 1997, pp. 87-101
The ontogeny of endocrine cells and nerve fibers containing immunoreac
tivities for 12 regulatory peptides and serotonin was studied in the d
igestive tract of a flatfish, the turbot (Scophthalmus maximus), using
antisera specific for mammalian and teleostean hormones. Transient in
sulin-immunoreactive (-IR) endocrine cells were detected from day 5 to
day 10 in stomach and intestine I. Somatostatin (SOM)-IR cells appear
ed at day 8 in the stomach anlage and intestine I. In contrast to the
islet cells, they reacted with antisera against mammalian (m) SOM-14 a
nd salmon (s) SOM-25. Infrequent nerve fibers reacting only with anti-
mSOM-14 appeared around day 24. Thus, different forms of SOM seem to b
e present in the gastro-entero-pancreatic system and the enteric nervo
us system. Neuropeptide Y (NPY)-, salmon pancreatic polypeptide (sPP)-
and mPP-immunoreactivities coexisted throughout development. In enter
o-endocrine cells, NPY/PP-immunoreactivity was first observed at day 8
and around day 24 in enteric nerve fibers. Glucagon (GLUC)-IR entero-
endocrine cells appeared at day 5. No coexistence of NPY/PP- and GLUC-
immunoreactivities was observed. The first insulin-like growth factor
I(IGF-I)-IR cells were identified around day 8. They seemed to contain
none of the other peptides. Their number and distribution exhibited g
reat interindividual differences. Vasoactive intestinal polypeptide (V
IP)-IR entero-endocrine cells appeared as late as around day 24. The f
irst VIP-IR nerve fibers, however, were identified at day 5. Infrequen
t neurotensin (NT)-IR cells appeared along the intestine around day 10
and NT-IR nerve fibers at day 17. The first serotonin (SER)-IR cells
were observed in the stomach anlage around day 10 and SER-IR nerve fib
ers at day 15 throughout the gastro-intestinal tract. Gastrin (GAS)/ch
olecystokinin (CCK)-IR cells appeared around day 11 in stomach and int
estine I. The first substance P (SP)-IR enteric nerve fibers were dete
cted around day 8 and SP-IR endocrine cells at day 11. Pancreastatin (
PST)-IR cells were identified in the stomach anlage and intestine I ar
ound day 8 and contained NT-, GAS/CCK- and SER-immunoreactivities in c
oexistence. Thus, several developmental phases can be distinguished: (
1) at the onset of exogenous feeding only transient INS-IR cells and V
IP-IR nerve fibers are present; (2) a differentiated entero-endocrine
system establishes during the early phase of exogenous feeding; (3) be
fore the final differentiation of stomach and gut GAS/CCK-IR cells app
ear; (4) after metamorphosis most of the different types of regulatory
peptide-containing nerve fibers develop, probably setting up the fine
regulation of gastro-intestinal blood flow and motility.