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EFFECTS OF CRANIAL CERVICAL GANGLIONECTOMY AND CASTP_.\TION ON ENDOCRINE AND MORPHOLOGICAL CHARACTERISTICS
A the s i s
of
Degr e e of
OF MALE LAMBS
pre s ented in p a r tial
the requ i r ements for Mas t er of 3c i ence in at Mas s ey Uni ve r s ity
��RK WARREN FISHER
1978
fulfilment
the
Phys icl o gy .,
ABSTRACT
EFFECTS OF CRANIAL CERVICAL GANGLIONECTOMY AND CASTRATION ON ENDOCRINE AND MORPHOLOGICAL CHARACTERISTICS
OF MALE LAMBS By Mark War r en F i s her
I n a s tudy of the e ffec t s of the p in eal gland on reproduc t ive deve l opment and ho rmone s ecre t i on , male l amb s were inco rporat e d into an over a l l 2 x 2 fac tor i al des ign in wh ich the exp e r imen t a l factors were:
(1) c r an i a l c e rv i c a l gang l i onectom i z e d or non - gangl ione c t om i z e d , and
(2) c a s trated or ent i re .
The f i r s t exp e r iment de s cr ib e d was a l ongi tudinc.l s t udy o f endo c r ine and morpho l og i c a l parame t e rs recorded
from the s e anima l s b e tween 7 and 37 weeks o f a g e. P l a sma
LH l eve l s in ent ire l amb s usua l ly were very low throughout the exp e r iment , a l tho
�
gh non - gangl ione c t omized entires did d i sp lay a sma l l e l evat i on i n l eve ls b e tween 8 and 13weeks o f age , wh i ch was not ev ident in gang l i one c t omi z e d -
ent i re s . At a l l age s p l a sma LH l eve l s were e l evated s ign ifi c an tly in cas t r a t e d anima l s . Ne i th e r
gangl i onec t omy n o r i t s inte r a c t ion w ith c a s t r ation had any s igni fi c an t e ffec t o n LH l eve l s . In ent i r e l amb s p l a sma t e s t o s t erone concen t r a t i ons incre a s e d from 7 weeks to highest concentrati ons b e twe e n
31
and 37 we e k s o f age.Ove ra l l , gangl i one c t omy reduc e d t e s t o s t erone s e cret i on ,
i i i but t h i s p r ob ab ly was due t o the lowe r body and t e s t i cu l ar we i ghts rec orded from that group... The norma l pho top e r i o d
induce d sea s onal p a t t ern o f pro l ac t in secre t i on in non - . gangl ionectomized l ambs , wi th h i gh levels dur ing the
summer -:ncnths and l ow dur ing wint er , was markedly
d i s rup ted by g ang l ione c t omy. Castr a t ion had no e f f e c t on pro l ac t in l eve l s and the interac tio11 o f ca s t rat ion and
gang l i on e c t omy a l s o was non - s i gn i f i cant .
Bodyweight was r educe d s ig n i f i c antly b y
g ang l ionectomy and t h i s e f f e c t wa s accentua t e d in the g ang l i onec t om i z e d c a s t r a t e s . At aut opsy , t e s t i cu l ar we ights and epid idyma l we ights a s we l l as ep i di dyma l s perm r e s erves w e r e r e duced , but not s i gn i fican t ly , by
gan g l ione c t omy ; th e s e r e su l t s p ro b ab ly r e flected the b odywe i ght o f th o s e an ima l s . Ne i th e r gangl i one ctomy nor c a s t r at i on had any s ign i f i c ant effe c t on p in e a l we i gh t s1 however t h e interac t i on o f the s e two fac t o r s was
s i gn i f i cant due to the very l ar g e p ineal of one o f the non - gang l i one c t omized c a s tr ate s .
A s ec ond exp e ri
�
ent invo lved mea surement o f LH,pr o l ac t in and t e s t o s t e r one p r o f i l e s in p l asma ob t a ined dur ing hour ly b l ood s amp l ings wh i ch were c onduc t e d for 24 hours when l amb s were b o th approximate ly 100 and 300 days o f age . At b o t h ages pul s a t i l e s e cr e t i on o f LH and t e s t o s t e r one was c on f i rmed , but no c i rcad i an rhy t hms o f LH , t e s t o s t e r one or pro l a c t in s e cr e t i on were de t e c t ed . C a s t rat i on e l evated L H l eve l s s i gn i f ican t l y at b o th a ge s . Gang l ione c tomy and i t s int e r ac t i on with cas t ra t i on had no e ffect on LH s e c r e t i on at lOO d ays , but at 300 d ays the s e
factors were s ign i f i cant l arge ly due t o e l evate d leve l s b e ing r e c o rd e d from gangl i one c t om i z ed cast r at e s .
Ganglione c t omy d i d not a f fe c t tes t o s t e r one l eve l s in e n t i r e animal s at ei ther age wh i l e cas trat e s had no
iv
d e t ectab l e t e s t o s t er one . Gangl i one c t omy r e duced p r o l a c t in c oncentr a t i ons a t 100 days o f age ( summe r ) and p r event e d the norma l wint e r de c l ine at 300 days o f age . C a s t rat i on and the int e r ac t i on o f c a s t r at i on w i t h gang l i onectomy had
no s ign i f i c ant influence on p l a sma pro lactin l eve ls at e i ther age .
P i tu i t ary LH and gonadal tes t o s t e rone r e spon s e s to 10 pg
s ynthe t i c GnRH wer e tes t e d at 100 days and 300 days o f age i n a t h i r d exp er imen t . In a l l an ima l s , GnRH eleva t e d LH l eve l s and in ent i r e s t h i s in turn res u l t ed in
incr e a s e d t e s t o s t e rone l eve l s . C a s trat i on sign i f i cant ly incr e a s e d b a s a l and peak LH l e ve l s t oge ther with t o t a l LH output . At b o th age s the LH and t e s t o s t erone re spons e s t o GnRH w e r e n o t influenced s ign i f i c ant ly by
gangl i on e c t omy , nor d i d the int e r a ct i on o f c ast r a t i on and gangl ione c t omy have any s igni f i c ant effe ct on LH s ecre to ry I
re spons e s .
The s e s tud i e s con f i rm the c oncept that the p i ne al . gland can inf luence the s e c r e t i on of p r o l actin , and
prob a b l y a l s o LH and t e s t o s t e rone , and thus may b e
invo lved in the regu l a t i on o f pub e r t a l d eve l opment i n r am l amb s .
ACKNOWLEDGEMENTS
I am ext r eme ly g r a t e fu l to my superv i s or
-
Dr . K . R . Lapwo od for h i s generous a s s i s t ance and guidanc e throughout the per iod o f t h i s s tudy .
P r o fe s s o r R . E . Munford i s thanked for va luab l e
advice w i th s t a t i s t i c s and for provi d ing fac i l i t i e s w i t h in the Department o f Phys i o l o gy and Ana t omy .
The fo l l owing are acknow l e d g e d for generous ly s upp lying mat e r i a l s u s e d in the rad i o immunoa s s ays:
Dr . G . D . N i swende r , C o l orado S t a t e Un ivers i ty , U . S . A . f o r ant i s e r a to t e s t o s t e rone and o v 1 n e LH ; Dr . L . E . Re iche r t Jr . , Emery Un ive r s i ty , U . S . A . fo r donat ion c f h i gh ly pur i f i ed ov ine p r o l a c t in ; P r o fe s s o r D . S . Flux , Ma s s ey Un ive r s i ty for prov i d ing ant i s era to ovine pro lac t i n ; and the Nat i onal P i tui tary Agency , N . I . A . M . D . D . , N . I . H . , U . S . A . for s t and ard prepar a t i on s o f ovine LH and
p r o l ac t in , h igh l y pur i f i e d ovine LH , and GnRH .
I am indeb t e d for the techn i c a l as s i s t ance prov i d e d by many peop l e throughout t h i s s tudy . In part icular ,
•
thanks to Mr . P . H . Wh i t eh e ad and h i s Mas s ey Un ive rs i ty sheep farm s t a f f ; Mr . R . H . T e l fe r , Mr . B . A . Vaut i e r and Mr . B . J . Mc L e o d for as s i s t ance w i th c o l l e c t ion of p l a sma
s amp l e s ; Mr . M . J . B i r t l e s for h i s t o l o g i c a l p r o c e s s ing ; Mr s . H . C a r t er , Mi s s C . A . Howe l l and Mr . H . J . E l gar for h e lp in the l a b o r a t ory ; Mr s . A. Larcen and Mr . T . G . Law for prep aring the f i gure s ; and Mr s . S . P icke t t , Mr . H . J . E l gar and Mrs . B . U . Curr i e for a i d ing in t he preparat i on of th i s the s i s . F in a l ly , thanks to my fam i l y for the ir cont inued
supp ort and encouragement throughout this s tudy .
TABLE OF CONTENTS
CHAPTER I: INTRODUCT ION . . . . . . . . . . . . A . Endocr ino logy o f ma l e r ep roduc t i on
1. Gene r a l . . .
2. The hyp o t h a l amus . . . . . .
3. Extr ahyp o t ha l amic influence s
4. Hypo tha l am i c hormon e s . . .
( i ) GnRH . . . .
. . . .
. . .
. . . .
. . .
( i i ) Pro l a c t iri � inhib i t irig -and -re l e asirig
P a g e 1
. . . 2
4 . . . 4
. . . 5
fac t o r s . . . 5 ( iii}: I n fluence of b r a in monoamines and
pro s t ag l and ins . . . . . . . . 6 ( iv ) Mechan i sm o f a c t i on o f hypothalamic
h o rmone s . . . . . . . . 7
(v) E f f e c t s of GnRH in s h e ep . . . 8
5. Ant e r i o r p i t u i t ary hormones . . . 9
( i ) LH and FSH . . . 9
( a ) Chem i s try and me t ab o l ism 9
( b ) Ac t i ons . . . . . . 10
( i i ) Pro l ac t in . . . . 11
(a) Chemis try and m e t ab o l ism . . . 11
( b ) Ac t i ons . 12
6. Te s t i cu l ar s t e r o i d s . . . . . . . . . . . 13 ( i ) Syn thes i s , s e c r e t i on and me t ab o l i sm . 14 ( i i) Act i ons . . . . . . . . . . . . . . . 15
7. Fe edb ack cont r o l cf the hyp o t h a lamo -
hypophys e a l�gonada l ax i s ·. . . . ( i) Hyp o t h a l am i c hormone s
( i i ) P i t u i t ary honnone s . . ( i i i ) Te s t i cu l ar hormone s
8 . Pat terns o f ho rmone s ecre t i on ( i ) Pul s at i l e hormone s e c r e t i on ( i i ) C ir c ad i an rhythms
( i i i ) S o c i a l and s exual s t imu l i ( iv) S tr e s s
9 . S e a s ona l i ty o f reproduc t i on ( i ) I nd i c a t i on s
v i i
Pag e
16 16
17
1 8 20 20 2 1 24 2 4 25 25 ( i i ) G onadot roph ins and t e s t i cu lar stero ids . 2 6 ( i i i ) P r o l a c t i n
( iv) Pho t op e r i od
2 8 29 (v) T r an s m i s s i on of phot op er i odic s t imu l i 3 1 B . Reproduct ive deve l opment
1 . F o e t a l . . . 2 . Po s tnat a l
( i ) B odywe ight , g onad s and r eproduct ive
t r a c t . . . .
( i i ) LH and F SH ( i i i ) Pro l ac t in
( iv ) T e s t i cu l ar s te r o i d s 3 . Ons e t o f pub erty . . . .
4 . I n f luen c e s o f genotyp e and env i r onment . C . The p in e a l g l and
1 . Ana tomy and innerva t ion
3 2
33
3 3 3 4 3 5 36 36 3 9 40 4 0
v i ii
P age
2 . B i o chemi s try . . 4 2
( i ) Indo l e am ines 4 2
( i i ) P o lypep t id e s . 46
( i i i) I nfluen c e o f p i tu i t ary and te s t i cular
h ormone s on the p ineal . . . 4 7 3 . P ine a l , pho t op e r i o d and s ea s ona l i ty
4. P in e a l and pub e r ty . . . .
D. Purp o s e o f the pre s ent s tudy
CHAPTER I I : MATER IAL S AND METHODS 1 . An ima l s . . . . . . 2 • An ima l man agement
( i ) On p a s ture ( i i ) Ind o o r s
3 . Surgic a l me thods
( i ) C r an i a l cerv i c a l g ang l i onect omy C a s t r a t i on . . .
( i i i ) Jugu l ar c annulat i on 4 . B l o od co l l ec t i on
( i ) L ong i tud ina l s tudy . •
48 so 5 1
5 2 5 2 5 2 5 2 52 5 3 5 3 5 3 5 3 5 3 5 3 ( i i ) 2 4 hour pro f i l e s and GnRH re spons e s 5 4 5 . Bodywe i ght dat a
6 . Aut op s y methods ( i ) H i s t o l ogy
( i i ) Ep i d i dyma l s p e rm r e s e rves
7. Hormone a s s ays ( i) LH . . . . ( i i ) Pro l a c t in
( i i i ) T�s to s t erone .
5 4 5 4
ss ss ss
ss
56 56
8. Exp e r imen t a l d e s i gn and ana lys is . . .
CHAPTER I I I : A LONG ITUDI NAL STUDY OF THE E FFECTS OF CRANIAL CERV I CAL GANGL I ONECTOMY AND
CASTRAT I ON ON ENDOCR I NE AND MORPHOLOG I CAL i x
Page 56
MATURAT I ON OF MALE LAMBS . . . 5 9
A . Introduct i on
B. Mat e r i a l s and Meth o d s C . Resu l t s .
5 9 6 1 6 2 1 . Long i tud ina l h o rmone s e cre t i on p r o f i l e s 6 2
( i) L H . . .
( i i ) Te s t o s t e r one . ( i i i ) Pro l ac t in
.2 . B odywe i ght . 3 . Aut opsy d a t a .
( i ) T e s t i cu l a r w e i ght s ( i i ) Ep i d i dyma l we ights .
( i i i ) Ep id idyma l sperm r e s erve s ( iv) Sem�n i fe r ous tub u l e d i ame t e r s
(v) P ine a l we i gh t s D . D i s cu s s ion
1. LII and t e s t o s t e r one
( i ) Non - gan g l i onectom i z e d ent i r e s ( i i ) T r e a t e d l amb s
2 . Pro lact in
( i ) Non - gang l i onectom i z ed ent i r e s
( i i ) T r e a t e d l amb s . . . . . . . . .
6 2 6 2 6 7
71
7 1 7 5 7 5 7 5 7 5 7 5 7 7 7 7 7 7 7 7 79 7 9 80 ( i i i ) Shear ing and p l a sma pro l a c t in l eve ls 8 1
3 . B odywe i gh t d a t a 83
4. Autopsy d a t a . . . 8 4
X
Pag e 5 . Gener a l d i s cus sion . . ..
CHAPTER I V : THE EFFECTS O F CRAN IAL CERV I CAL
GANGL I ONECTOMY AND CASTRAT I ON ON 2 4 HOUR PLASMA PROF I LE S OF LH, TESTO STERONE AND PROLACT I� I N PUBERTAL AND POST - PUBERTAL
8 5
MALE LAMBS . . . 8 7 A. I n t rodu c t i on
B . Materia l s and m e t hods C . Re su l t s .
1 . LH s ecret ory p ro f i l e s 2 . Te s t o s�erone .
3 . Pro l ac t in D . D i s cus s i on
1 . Pul s a t i l e h o rmone s e c r e t i on 2 . C i rcad i an p e r i od i c i ty
3 . C a s t r a t icn . . .
4 . Cran i a l c e rv i c a l gang l i onect omy
CHAPTER V: THE EFFECTS OF CRAN IAL CERV I CAL
GANGL I ONECTOMY ON P I TU I TARY LH AND GONADAL TESTOSTERONE RE SPONS E S , AND OF CASTRAT ION ON P I TU I TARY LH RE SPONSES , TO EXOGENOUS GnRH IN PUBERTAL AND POST - PUBERTAL MALE
8 7 8 8 89 8 9 . 103 . 1 10 . 1 2 1
1 2 1 . 1 2 3 . 1 2 5 1 26
LAMBS . . . 1 2 9
A. Introduc t i on
B . Mat er i a l s and Me thods . C. Re s u l t s
1 . L H . .
2 . Te s t o s t e rone D . D i s cus s i on
. 1 2 9 130 . . 1 30 . . 1 30 . . 1 4 4
1 5 2
CHAPTER VI : GENERAL D I SCU S S I ON AND CONCLUS I ONS .
1. S exua l maturat i on in r ams
2 . C r an i al cerv i c a l gang l i onectomy . . . 3. B odywe i ght . . . . . . . . . .
4 . Pro l ac t in
5. The p in e a l and pub e rty .
xi
Page
. 156 . 156 . 159 . . . 16 2
. 163
. . 165 6. Pos s ib l e app l i c a t i ons o f the pre s en t s tudy 168
Re ferences . . . . . . · · · · · · · · · · · · · · · . 170
L I ST O F F I GURE S F igure
3 . 1 Me an p l a sma LH c oncentra t i ons re corded from
Page
l amb s b e twe en 7 and 3 7 we eks o f age . . . 6 3 3 . 2 Me an p l a sma t e s t o s t e r one concent ra t i ons
recorded from l amb s b e twe en 7 and 3 7. weeks
of age . . . 6 5 3 . 3 · Mean p l a s ma pr o l ac t in concentr ations
recorded from l ambs b e tween 7 and 37 weeks
of age . . . . . 6 8 3 . 4 Mean p l a sma pro l ac t in concent r a t i on s
recorded from l amb s b e tween Novemb e r 19 76
and May 19 7 7 . . . 7 0 3 . 5 Mean b odywe i gh t s r e c o rded from lamb s b e tween
7 and 37 we eks of age . . . . . 72
4 . 1 Ind iv i dual 2 4 hour pro f i l e s of p l a sma LH l eve l s re corded from 6 non - gang l i one c tomized
ent i r e lamb s a t 10 0 days o f age . . . . . 9 2 4.2 Indiv idua l 24 hour p r o f i l e s o f p l asma LH
l eve l s recorded from 6 non - gang l i onectomi z e d
c a s t r a t e l amb s a t 10 0 days o f a g e . . . . 9 3 4 . 3 Individua l 24 hour pr o f i l e s o f pl a sma LH
l eve l s recorded from 6 gan g l i onect om i z e d
ent i r e lamb s a t 10 0 days o f a g e . . . . . 9 4
4 . 4 Ind iv idual 24 hour p r o f i l e s o f p l a sma LH leve l s recorded from 6 g ang l i onect omized
c a s t r a t e lamb s a t 10 0 days of age . . . . 95 4 . 5 Me an 24 hour p l a sma LH p r o fi l e s r e c o rded from
l amb s at 10 0 days of age . . . 9 6 4 . 6 Ind iv idua l 2 4 hour pro f i l e s o f p l a s ma LH
l eve l s r e c o rded from 6 non - gang l i onectomi z e d
ent i re l amb s a t 30 0 days o f a g e . . . 9 7 4 . 7 . Ind i v i dua l 2 4 h our p r o f i l e s o f p l asma LH
·leve l s r e c o r d e d from 5 non-gang l i onect omi z e d
c a s t r a t e l amb s at 30 0 day s o f age . . . . 9 8 4 . 8 Ind iv idua l 24 h our pro f i l e s o f plasma LH
l eve li r e c o r d e d from 4 gang l i on e c t om i z ed
ent i r e l amb s a t 30 0 da
y
s o f age . . . 9 9Figure 4 . 9
4 . 1 0
4 . 1 1
4 . 1 2
4 . 1 3
4 . 1 4
4 . 1 5
4 . 1 6
4 . 1 7
4 . 18
4 . 1 9
4 . 2 0
Ind ividual 24 hour pro f i l e s o f p l a�ma LH l eve l s r e corded from 5 gang l i onectomized
.Xi i i -
Page
c a s t r a t e lamb s a t 300 days o f age . . . 1 0 0 Me an 2 4 hour p l a sma LH pro f i l e s r e c o rded
from Iambi a t 3 00 d ay s o f a ge . . . 1 0 1 I nd iv i du a l 2 4 hour p r o f ile s o f p l a sma
t e s t o s t e r one leve l s r ecorded from 6 non g ang l i onectomi z e d ent i r e l amb s at 1 0 0 days
of age . . . 1 0 4 I nd iv i dua l 2 4 hour p r o f i l e s o f p l a sma
t e s t o s t e rone l eve l s recorded from 6
g ang l i on e c t omi z e d ent ire l amb s at 1 0 0 days
of age . . . 1 0 5 Me an 2 4 hour p l a s ma t e s t o s t e r one p r o f i l e s
re corded from l amb s at 1 0 0 days o f a g e . . . 1 0 6 Ind iv i dua l 2 4 hour p r o f i l e s o f p l a sma
t e s t o s t e rone l e v e l s re corded from 6 non gang l i onectom i z e d ent i re lamb s at 3 0 0 days
o f age . . . 1 07 Indiv i dual 2 4 h our pro f i l e s o f p l a sma
t e s t o s terone l e ve l s recorded from 4
gang l i onectomi z e d ent i re l amb s a t 3 0 0 days
of age . . . 1 0 8 Mean 2 4 hour p l a sma t e s t o s t e rone p r o f i l e s
reco rded from l amb s at 3 0 0 days o f a g e . . . 1 0 9 Ind i v i dua l 2 4 hour pro f i l e s o f
pro l ac t in l eve l s re corded from gang l ionectom i z e d ent i r e l amb s o f age . . . . . . .
p l a sma
6 n o n -
a t 1 00 days Ind ividua l 2 4 h our pro f i l e s o f p l asma
pro l a c t in l ev e l s recorded from 6 non gang l i one c t om i z e d c a s t r a t e l amb s a t 1 0 0 days o f age . . . .
Individua l 2 4 hour pro f i le s o f pro l a c t i n l ev e l s recorded from gang l i onect omized ent i r e l amb s
of age . . . .
p l asma
6 a t 1 0 0 days
I nd iv i dual 2 4 hour pro f i l e s of p l asma p r o l a c t in l e v e l s recorded from 6
g ang l i on e c t om i z e d c a s t r ate l ambs at 1 0 0 days o f age . . . . . . .
1 1 1
1 1 2
1 1 3
1 1 4
F igur e 4 . 2 1
4 . 22
4 . 2 3
4 . 2 4
4 . 2 5
4 . 2 6
Mean 2 4 hriur p l a sma pro l a c t in p rofi l e s re corded fr om l amb s at 1 0 0 days o f a g e Individu a l 2 4 h o u r p r o f i l e s o f p l asma pro l ac t i n l eve l s r e co rded from 6 non -
. gang l ione c t omized ent ire l amb s at 30 0 days o f age . . . . . ·Cl • • • • • •
Individual 2 4 hour pro f i l e s o f p l a sma pro lact in l eve l s r e corded from 5 non g angl ion e c t omi z e d c a s t r a t e l amb s a t 3 0 0 days o f age . . . . . . . . . . . . . .
Individual 24 hour pro fi l e s of p r o l ac t in l e ve l s r e c orded from g ang l i on e c t om i z e d ent ire l amb s days o f age . . . . . . . . .
p l a s ma 4 at 3 0 0
Individual 2 4 hour p r o f i l e s o f p l a sma p r o l ac t in l e ve l s recorded from 5
gang l i one c t omi z e d c a s trate l amb s a t 300 days o f age . . . . . . . . . . . . . Mean 2 4 hour p l a sma p r o l ac t in pro f i l e s recorded from l amb s a t 3 0 0 days o f age
5 . 1 P l a sma LH p r o f i l e s fo l l owing admin i s trat i on o f 1 0 pg GnRH ( imme d i ate ly after the z e r o min s amp l e ) t o 6 non - gang l i onect om i z ed
xiv Page 1 1 5
1 1 6
1 1 7
11 8
1 1 9
1 2 0
ent i r e l amb s a t 1 0 0 days o f age . . . . 1 3 3 5 . 2 P l a sma LH p r o f i l e s fo l l owing admin i s t r a t i on
o f lD pg GnRH ( imme d i a t e l y a f t e r the z e r o min s amp l e ) t o 6 non - gang l i onec t om i z e d
c a s t r a t e l amb s a t 100 days o f age . . . . 1 3 4 5 . 3 Plasma LH p rof i l e s fo l l ow ing admin i s t r a t i on
o f 1 0 pg GnRH ( immed i a t e ly after the z e r o min s amp l e ) t o 6 gang l i onec t omi z ed ent i r e
l amb s at 1 0 0 d ays o f a g e . . . . 1 35 5 . 4 P l a sma LH pro f i l e s fo l l owing adm ini s trat i on
o f 1 0 pg GnRH ( imme d i at e ly a ft e r the z ero min s amp l e ) t o 6 gang l i on e c t om i z e d c a s t r a t e
l amb s a t 1 0 0 d ays o f age . . . 1 3 6 5 . 5 Mean p l a s ma LH p r o f i l e s fo l l ow ing GnRH
admini s tr at i on ( immed i a t e ly a f t e r the z e r o
min s amp l e ) t o lamb s at 1 0 0 days o f age 1 3 7 5 . 6 P l a sma LH p r o f i l e s fo l l owing adm in i s t ra t i on
o f 1 0 pg GnRH ( immedia t e ly a f t e r the z e r o m i n s amp l e ) t o 7 non - gangl i on e c t omi z ed
ent i r e l amb s at 3 0 0 days o f a g e . . . . 1 3 8
F igure 5 . 7
5. 8
5 . 9
5. 1 0
5. 1 1
5. 1 2
5. 1 3
5. 1 4
5. 1 5
P l asma L H p r o f i l�s f o l l owing admin i s t r a t i on o f 1 0 pg GnRH ( imme d ia t e ly a f t e r the z e r o min s amp l e ) t o 6 non - gang l i onectomi z e d
c a s trate 1 am b s a t 3 0 0 day s o f age . . . . . P l a sma LH p r o f i l e s f o l l owing admin i s t r a t i on o f 1 0 pg GnRH ( immed i a t e ly a f t e r Lhe z e r o min s ampl e ) to 6 gang l i one c t omi z e d ent ire
l ambs at 3 0 0 days o f age . . . . . . . . . P l a sma LH profi l e s fo l l owing admin i s t r at i on o f 10 pg GnRH ( imme d i a t e l y a f t e r the z er o min s amp l e ) to 5 g ang l i on e c t omi z ed c a s trate
l amb s at 3 0 0 days o f age . . . . Me an p l a sma LH p r o f i l e s fo l l owing GnRH
admin i s t r a t i on ( immed i at e l y a fter the zer o m i n s amp l e ) to l amb s at 3 0 0 days o f a g e . .
Plasma t e s t o s t e r on e pro f i l e s fo l l ow in g admin i s t r a t i on o f 1 0 p g GnRH ( imme d i a t e l y after t h e z e ro m i n s amp l e ) t o 6 non
g angl i onectomi z e d ent i r e l amb s at 1 0 0 days of age . . . . . . . . . . P l asma t e s t o s t e rone pro f i l e s fo l l owing admini s t r a t ion o f 1 0 pg GnRH ( immedi ate l y a f t e r the z e r o min s amp l e ) to 6
g ang l i onectomi z e d ent i re l amb s at 100 days o f age . . . . . . . . . . P l a sma t e s t o s t e rone p r o f i l e s fo l l ow i ng GnRH admi n i s t r at i on ( imme d i a t e l y a f t e r the z er o m in s amp l e ) to l amb s a t 1 0 0 d ay s o f age . . . . . . . . . . . . . . . · · · P l a sma t e s t ost e r one pr o f i l e s fo l lowing admi n i s trat i on o f 10 pg GnRH ( immed i ately after the z e r o min s amp l e ) to 7 non
gang l i one c t om i z e d ent i r e l amb s a t 3 0 0 days of age . . . . . � . . . . . . . . . . P l a sma t e s t o s t e r one p r o f i l e s fo l l ow i ng admini s tra t i on o f 1 0 �g GnRH ( imme d i a t e ly a f t e r the z e r o m in s amp l e ) to 6
gang l i one c t om i z e d ent ire l amb s at 3 0 0 days o f age . . . . . . . . . . . . . 5. 1 6 Mean p l asma t e s t o s t e r one p r o f i l e s fo l l owing GnRH admin i s t r a t i on ( immed i a t e ly a f t e r the z e r o min s amp l e ) to l amb s at 3 0 0 days o f
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1 4 0
14 1
1 4 2
1 4 5
1 46
147
1 4 8
1 4 9
age . . . . 1 5 0
