الفهرس 
Material and methodsOnly 14 pages are availabe for public view
 |  | from | 299 |  |  |
| | | from | 299 | | |
Abstract
The present work includes a study of morphological and h i s t o l o g i c a l s t r u c t u r e s i n the p i t u i t a r y gland of d i f f e r e n t species of t e l e o s t s i n the Egyptian waters , namelydilapia nilotica , Tihpia galilaea, T i l a p i a -zillii, Clarias lazera Letes niloticus, chrysichthys -9 - aumtus, Malapterurus e l e c t r i c u s , and Hvdroc~us f o r s k a l i i . A description of the topography of the p i t u i t a r y glands both adenohypophysis and neurohypophysis i n these species is given as well as the d i f f e r e n t types of the neurosecretory substances (NSS) . The p i t u i t a r y gland is attached to infundibular region of the brain by an infundibular s t a l k . It has two main region: the adenohypophysis and the neurohypophysis. I- The adenohypophysis is divided into three main regions; rostra1 pars distalis (RPD) , proximal pars distalis (PPD) and p a r s intermidia (PI). There is no sharp l i n e of separation between these zones but they were recognized by using many s t a i n s and through identify iog t h e i r c h a r a c t e r i s t i c c e l l types. The arrangement of the different c e l l types and t h e i r relative location to each other and also t h e i r sizes are not the same in a l l cases in the three regions of the adenohjpophysis. 1.1 - Rostra1 pars distalis (RPD) region in a l l spec’ies examined occupies the most anterior portion of the gland and its relative s i z e v a r i e s from one speci e s to another. It is occupied mainly by two acidophilic c e l l types, prolactin and corticotropic c e l l s (ACTH c e l l s ) . 1.1.1- The prolactin c e l l s a r e predominate in the RPD region and are arranged e i t h e r in a f o l l i c u l a r sbpe a s in Clarias lazera and Chmaicbthys auratus, or distributed throughout the RPD region a s i n Tilapia species (-T. n i l o tica, -T .palilaea, and -T. eillii) ,Lates niloticus, Malapterurus electricus and Hydrocynus forskalii. These c e l l s are distinguished by t h e i r a f f i n i t y toward azocamine in azan technique and t o acid fuchsin. 1.1.2- Corticotrophic c e l l s (ACTH c e l l s ) a r e present e i t h e r s c a t t e r ed a s in Tilapia g a l i l a e a , -T. aillii and Malapterurus electricus, or scattered and border ing the neurohypophysis as i n -T. n i l o t i c a , Lates n i l o t i c u s , chr.ysichthys auratus and Hydrocynus f o r s k a l i i or f om, along band in between the WD and PPD region at the ventral. side as in Clarias laeem . These c e l l s a r e characterized by their strong affinity towazd FbH. These c e l l s could a l s o be detected in PPD region of some s p e c i e s examined a s in -T. z i l l i i chrysichthys auratus , -9 Malapterurus e l e c t r i c u s and Hydrocynus f o r s k a l i i . thqrotrophia c e l l s (TSH c e l l s ) could be detected s c a t - t e r e d in rCPD region in T i l a p i a s p e c i e s (-T. n i l o t i c a , -T. p a l i l a e a and -l ’.z illii), chr~sichthysa u r a t u s and ikhlaptentrus e l e c t r i c u s . These c e l l s are t y p i c a l l y basophilic c e l l s and could be distinguished by t h e i r a f f i n i t y towa-rd AP as well as by t h e i r morphological properties. 1*2-Proximal pars distalis (PPD) region is the middle pmrtion of the p i t u i t a r y gland and v a r i e s i n its r e l a t i v e size from one species to another, and composed mainly of three c e l l types in a l l species examined, two basophilic c e l l types (thyrotrophs (TSH c e l l s ) and gonadotrophs (GTH c e l l s ) , and one acidophilic c e l l type (so~ttorophs) ( STH c e l l s ) . Beside these type of c e l l s , a l i t t l e number of weakly acidophilic or nongranular c e l l s known a s chromophobes are present in t h i s region. The amount of the basophils and acidophils were different from species to another. 1.2.1- Thyrotrophic c e l l s (TSH c e l l s ) a s \*!ell a s gonadotrophic cells (GTH c e l l s ) present either scattered a among the PPD region without any definite arrangement a s in Clar ias lazera, -Ch rysichthys auratus and and Malapterurus electricus, o r in isolated patches among the PPD region a s Fn Tilapia species (2. n i l o t i c a , -T. g a l i l a e a , and -T .zil1i.i) o r located scattered and in patches together a s in Lates nilo ticus and Hydrocynus forskalii. The GTH, cells are distinguished by their affinity toward l i g h t green staining but the TSH c e l l s are stained with AF . 1.2.2- Somatotrophic c e l l s (STH c e l l s ) are stained with orenge G in azan technique i n a l l species examined. They vary in their distribution and their sizes. In some species these c e l l s were either scattered among the two basophilic c e l l types in the PPD region a s in Clarias lazera, chrysichthys auratus and Y~lapteruruse l e c t r i c u s o r bordering the neurohypophysis and in between the interdigitate of it in PPD region as in Tilapia species (2, n i l o t i c a , 2 . galilaea, and -T. zillii) , La t e s n i l o t i c u s and Hydrocynus forskalii. .3- Pars intermedia (PI) region is the most poaterior part of the gland and its relative size d i f f e r s from one species t o another. It is composed of melano troph acidophilic c e l l s ( MSH c e l l s ) which are present only in the PI re&ion. These c e l l s are stained light red w i t h azocarmine in azan technique and gray to black with PbH in a l l species examined. They are PAS~negative and AF- negative. Their shape and size varies from one species to another. Some c e l l s in the PI region are almost chromophobic which show no a f f i n i t y for the dyes used. GTH2 c e l l s could be detected scattering in the P I region of some species as in Clarias lazera, Lates niloticus and Hydrocynus f o r s k a l i i , but in other species studied they could not be detected. The GTHZ c e l l s are distinguished by t h e i r a f f i n i t y toward light green. These c e l l s were distinguishable from MSH c e l l s in the same region by t h e i r positive response to PAS and aniline blue and also by t h e i r negative response to azocarmine. They a r e a l s o distinguished from GTH c e l l s of 2PD region by t h e i r positive reaction toward PbH s t a i n . Some TSH c e l l s could be detected suattering in the region of Tila pia species (T.nilotica, T. galilaea and T. z i i i ) a r i a s lazem, and Malapterurus electr- 11- The neurohypophysis is characterized by a highly branched network of f i b r o i d material which is continuous with the infundibular s t a l k . Its ramifications penettate a l l the glandular portions to varying degree in a l l species examined. The s t a i n i n g i n t e n s i t y of the hypopbysial region depend upon the amount of the neurosecretory substances (MSS) present. Several scattered p i t u i c y t e s were present in the neurohypophysial s t a l k . There are two types of neurosecretory f i b e r s ( NSF ) i d e n t i f i e d in the neurohypophysis of a l l species examined, type A NSF stained with AF technique and type B NSP stained with azocarmine in azan technique and PAS stain. Discussion of the r e s u l t s in view of the relevant literature is given as well as coloured photo and t a b l e s to i l l u s t r a t e the obtained r e s u l t s a r e a l s o provided.