الفهرس 
Gland organizationOnly 14 pages are availabe for public view
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Abstract
Histological and histochemical examination of the p i t u i t a r y of channel c a t f i s h , I c t a l u r u s punctatus (Rafinesque), revealed four acidophilic and three basophilic c e l l types, Acidophllic cells exhibited no seasonal a c t i v i t y patterns and included: prolactin c e l l s (in rostra1 pars d i s t a l i s , RPD), ACTH cells (in RPD and proximal pars d i s t a l i s , PPD), STH c e l l s cin PPD), and MSH cells (in pars intennedia, PI). Acidophils were found t o contain tyrosine, h i s t i d i n e , a - amino groups and carboxyl groups, but no tryptophan, argin5ne, or lipid. The a c t i v i t y of basophils varied seasonally. TSH c e l l s were the only basophils positive to aldehyde fuchsin (AF), and were located primarily in the PPD, with a few patches of c e l l s in the RPD and PI. TSH cells reached a maximum size i n February and a minimum size i n August, Two different gonadotrophic (GTH) c e l l s were identified based on location, staining response and the effect of estrogen injection. One type i n the PPD occurred only in mature fish. Changes in size of these mGTH (maturational GTH) c e l l s correlated with gonadal maturation, reaching the maximum size in the spring when spawning normally occurs and a minimum size by f a l l . A second type of gonadotroph (gametogenetic; gGTH) in the PI differentiated in juveniles and increased in size only in the f a l l when gametogenesis occurs in catfish. Basophils contained cystine and/or cysteine, a - amino carboxyl groups, SH and SS groups, but no lipid, tryptophan or arginine. The potential for cross-linkage indicates that proteins of basophils may be structurally more complex v i i i than those of acidophils. Two types of neurosecretory fibers (NSF) were identified in the neurohypophysis. Type A w e r e AF-positive, appeared in juveniles, and were concentrated in the PI. Seasonal changes in staining i n t e n s i t y suggested that these fibers regulate the a c t i v i t y of gGTH c e l l s to i n i t i a t e gametogenesis. Type B NSF were AF-negative, were present only in mature fish, and were concentrated in the PPD. The seasonal changes in staining intensity of these cells indicated that these fibers may control mGTH c e l l s which influence gonadal changes that r e s u l t in spawning in the spring.