Digitized 2007 AES.Includes bibliographical references (page 10)

Day, B. N.

Romack, Frank Eldon, 1924-

Turner, C. W. (Charles Wesley), 1897-1975

University of Missouri: MOspace

RESEARCH BULLETIN 838 NOVEMBER, 1964 UNIVERSITY OF MISSOURI COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION ELMER R . K IEHL, Dimtor Anatomy of the Porcine Thyroid F. E. ROMACK, C W . Tuu"u. ANI') B. N. DAY ( Public:uioD Authorized Nov. 19, 1964) COLUMBIA, ~USSOURI CONTENTS Introduction . . ... ... . .. ... .. . .. ... .. .. . ........ . Methoos md Materials Results and Di=ion Literature SUMMARY , , 4 ..... ..... . 10 Tissues ventral to the porcine thyroid were dissected ro establish rhe rela· t ionship of {heK Strucrures 10 the thyroid gland. Arterial supply and venous drainage of the thyroid gland Wete also determined. DisKcred thyroid glands of swine were located in the peritracheal fas.::ia vemralto the trachea. Longitudinal position of the gland ~ied from the cauo:W ventr:tl border of the larynx to 2 position dorsal to the manubrium sterni. The average thyroid gland weight of n swine, representing different breeds and Kxes, was 4.93 gm. per 100 pounds of body weight. Injected iodine lUI was found to concentrate in the thyroid gland of swine with litde 1''' uptake by other body oryns. Anatomy of the Porcine Thyroid f . E. ROMACK, C. w. TtiRNU AND B. N. DAY IN T RODUCTION Swine are g~ini ng importance as experimcnt~ [ animals in fundamcmal studies 1S a re5uit of the r<"(ognilion of the many simiwcies beo.-een their phys-iologia.J systems and those of man. The gamo-inrcstinal traCI is provided with a simple sronuch vcry similar to {hal of man. The ability of swine to store fiu has been compared wilh adIpose depots in man and cardio.v<lscular conditions such as atherosclerosis arc now being studied in aging swine_ A more complete evaluation of the anatomical and biological characteristin of swine would be useful in order 10 establish a more 511lldardized physiological dcs<:riprion of ,his Sp«lCS. The present study of the anatOmy of the thyrOid ghnd of swine was ini· dared to describe, morc compl~tdy, individual variations in the ~natomic:Jl StrUCture of (his gland and to us~ th~se findings in (he development of a pm. cedure for determining daily thyroxine se.::fetion FoItC of swm~ (stt Romack, 196;). METHODS AND MATERIALS To dctermine, initially, the anatomical location of the Pfocine thyroid gland and iu associated anatomical StrUCtures, an animal was embalmed . n<! topographically diss<:<:ted (0 reveal the detail in structural arrangement in the area of (he thyroid gland. Observations were rhen made on additional cadavers and on carcasses of sb ughter animals to describe individual variations in loca· tion and size of {he porcine thyroid. To determine the function al level of accessory thyroid tissue existing in swine and to determine th~ level of upuke in vuious body tissues, iUl animal was injected with 200 microcuries of 1' '' and allowed a three day period for maximal uptake and accumulation of I'''. The animal was ~crifittd and a seuch was made for 1''' throughout the body tissu<'5 by using a radiation coum·nut-mettt with lead shielding on the probe crysal to el iminate extr2-ndiation count· mg. MlSSOIJi.1 AGRIClILTlJIlAL ExPERIMENT SV,T10:< RESULTS AND D ISCU SSION To expose the thyroid gland, a mid-vemral incision was !IUde through rhe skin and subruaneous adipose tissue. Reflection of this rissue reveal"'! the mus-cles vemNoI to the rhyroid gland. These are rhe superficial CUNoncous coUi muscle fibers, rhe right and left 5,ernocephalicus mu:;.:;les >rid the right and left sterno-hyoideus muscle. Tissues from the parotid sali~y gland were found in ,his area l!l some specimens (Figures I, 2 and 3). The position of the thyroid "aned among individuals. In some wimais, the cranial extremity of the thyroid was resting on the caudal border of the larynx, while in Others the thyroid was posi. t ioned nudally '0 the extem that it was i(>(";lted dorsal to rhe manubrium stemi. Similarly, Sisson and Grossman (19~3) reported that the thyroid of swine is usually some dim.nce from the larynx, but it lTllIy also be found in comacr with rhe nudal extremiry of the larynx. Arterial blood supply and venous drainage from the thyroid gland are shown in Figure 3. The primary artetial supply approaches the dorsal SUrnq of the right nudal border of the thyroid gland '5 the thyroid mery. The thyroid artery arises from the right omocervinl artery (inferior cervical). In some s~i. , • ,- -- -- ~ , . " . .. AU .... ""GED Fig. l-Schenu[ic drawing of the tissues yen' .... l to [he thyroid gbod. Fig. 2-Dissection of the tissues ventra! to the thyroid gland. T".,ROIO vt", --- ,,~ Fig. 3-Schenutic dtllwing of the tissues and anuomi<;:l.i strucru= in .-elation to the thyroid gbnd (ventol view). 6 MISSOURI AG1UCU~TURA.L EXP21UMENT SUTION mens ~ second thyroid utuial bnnch supplied til .. dors..! sUrhce of the rhyroid gland on ,he kft caud..1 border. This ane,i.l branch, when present (observed in less than 25 I""',cem of the obscrv"ions), arises from the left common «lradd ulery. Some anerial blood is supplied to the thyroid through capillaries and uterioles located along d~ b'Wll, dorsal, and enni.1 borders of the gt"nd which anastomose with the meries loclted in the peritracheal fll5cia. Sisson and Gross-man (19H) ifate that the posterior thyroid artery arises from the ascending b .... nch of the inferior cervical artery. Two thyroid v.:ins were present in all anirru.ls srudie<!. The right ,,<,in leaves (he postcrior exm:mity of the gland and courses caudaUy and later:ally, emptying into the right external jugular vein neor its junctu.-c with the right imernal jugu-lor vein. The kft thyroid vein wu abollt OM-third as large as the right and showed an occasional anastomosis with 1 branch of the lorynged veins. The normal pathway of the left thyroid vein and its rerminarion was similar to that of the right vein. Similar findings have been repow:.:! by Caylor and Schlott-hailer (1927) ond St. Clair (19'8). The porcine thyroid gland is a bilohed gland connected by 1 very luge isrhmlls . It appears, on ca51111 observadon_ 15 a single ghnd as shown in Figu"" ,. Thyroid glands were dissected from 2) adlllr anim.ts to determine averag<: gland weight . Dat1 are presented in T.ble I for Poland o,ina boars and Duroc and Hampshire sows. The average gland weight for both sexes wu 4.93 gm. per 100 pollnds of live weight . • ThyroId gl'1ffd Fig. 4_ T he relationship of the porcine thytoid gland 10 the luyn>: , ,neM, and esophagus (btenl view). RESEARCH BULLETIN 838 7 TABLE 1 - THYROID GLAND WEIGHTS OF 23 ADULT S\\IlNE Boo, Thyroid Gram. Per 1~0 Breed" Sex Number Wtlght Gland WI. Lb • • Body WI . B-I0S ,~ 22.90 gm. ~.4~ B- 38 '" 23.50 gm. 6.25 B-226 '" 26.32 gm. 8.0S '""'" B-179 '" 23 . S0 gm. 7.01 ... ~ B- 12 '" 14.40 gm. 4.88 B-l85 '" 11 . 30 gm. 3. 12 B- 33 '" 21. 80 gm. 7.93 B- 143 ". 19.40 gm. 7. S2 Average '" 20.39 gm. 6 . 28 S -U4 .., 19.30gm. U S -251 '" 16 . 77 gm. 4. 51 S- 22 '" 17.04 "". 4 . 77 = S -232 ,~ 13.33 gm. 4.38 &wo ,. ,. '" 14 .00 gm. 3.76 S-332 '" 10 . 32 "". 3 . 62 S- 31 '" 11 .03 grn . 3 . 33 S- 24 '" 12 .00 p. 3.02 5-238 '" 8.45 gm. 3 . 35 Average '" 13 . 58 gm. 3.95 S-2'\3 '" 14.$3 gm. 5.23 8-103 ,~ 16.90 gm . 5 .60 HampShire S-227 '" 8.33 gm. 3.12 -8_222 '" ll.9O gm . 3.83 8 - 295 '" 8.35 gm. ,. ,. 5-162 ". 16.92gm. 7.11 A,-e ragt '" 12.82 gm. 4.62 Avuage All Anlmala '" 15.75 gm. 4 .93 The Poland China boar:; thai were stu.died had. an average body weighl of 331 pounds and an averllge thyroid weight 0( 6.28 gm. pet 100 pounds of body weighl. This was somcwh:tt higher than that found in Hunpshire sows ,",ocigh· ing an avenge of 282 pounds; their avenge gland weight was 4.62 gm. per 100 pounds of live weight. These gland weights were somewhat higher than those lfldicatro by B1ird tl at. (19'2) who reported an average thyroid weight of U6 gm. per 100 pounds of live weight for a rapid·growing strain of pigs. Table 2 summarizes the results obtained from an animal that had been in· jecred wilh I'" thl"« days prior to sacrifice. A background re:uling of 1.5 counts per second was measurro which has to be considered in evaluating all value! given in Table 2. Small amountS of radioaCtivity were present in the thymus, splcen, pancreas, gall bladdu, hC2r! and adten21 gland. Slightly higher rcsiducs were recorded for the liver. colon, blood, kidney, and lung. Bustad (1961) re-B MISSOUl.! ACRICULTUUL ExP:ERiMENT STATIO:'; • , • , , Caudill , ~ • ,. ' .' f ig. S-Fou .. porcine .hyroid glands d.,moDIt I"l';ng v:>.riuion found in shape of ,he gland (veneral uPC("[.) TABLE 2 - RADIO -ACTIVITY OF DISSECTED TISSUES AIm ORGANS OF A GROWING PIG INJECTED \\11TH 1131 Mand!bWu lymph node Mandibular ,all" ... y "and T>ym~ U"' B._ P ... ., .... GAll Bladder ,~­""""'.~ ColO1l .,.,., Heart, R. Autl.,l. H'.rt, R. Ventricular muIIete Abclom1nllllymph node Adr.nuBlan<! ~ .. , "'"" LllInboucul U'IIa (body mas.) C.rvIcot.hor.elc are. (body rna .. ) ThyrOid ,Land RadiO -ACtivity, COWlta/Sec . '-' '-' '-' ,., '-' '-' '-' '-' '-' , .. , .. '-' '-' '-' '-' , .  '-' 10.0 " .. 1250,0 RESiAJ.CH BU1UT!N 83.8 9 ported dlat the g1'Otest IO$S of I '" from SWiM was through urine aaetm As ~s .:xpcac:d, a high concent rltlon of , ,.. ~s found in d>c: ' hyroid gland. Body !nUS recordings were made after rhe ti!.Sucs and Ofg1m lilttd in T abk 2 were removed from the carca!.S. The higheI reading in the cc:rvico rhoracic arC2 than in the lumbosarn.lar<:a WlS believed to be due to the lar~ residual blood volume present in the fonner area. 0{ perhap$ the P'C"$CIlCC of small amounll of accessory thYIoid tissue in Ihis al"O. However, accessory thyroid tissue wu nor: detected in any of the di$$CCted cadavers 0{ !laughter aninu1.s in spite of c:arcfuI and detailed searching. It hu been observed in I sqnr"ltC nudy (unpublishal data) that surgial relllOV1l1 of porcine thyroid glancb will, within twO months time, result in the prolifcratlon of acces.socy thyroid and/ ot mesrnchymll cell.$ to the extent that many grotCS<jue gm .... ths of thyroid tissue may be found by dissect ion or as indicated by the uprakc of I"'. These structures contlin well. developed follicular SlrucNtCS wirh normal StOrel of thyroglobulin Ind may be found in the peritraCheal fascU from tru:, level of the: larynx caudally as far 1.1 the: thoracic inlc:!. Recent "","(Irk by Schmidt tt.d. (1960') indiates that accessory thy· roid tissue: proiimtcs to I subswuial e,Uent within 3) days. The prc:scnce of acceSSOf)' Ihyroid tiUlle in ,he pig hl$ :also been rc:portal by uylor and Schlol1hlUCl" (1927) who observed u many as six acctSS<X)' glancb in one: aninul. These are described 1$ mI:al1 pink bodies, one 10 th= cemimclen in diametcr and usually siluated in loose: connective tinuc on the tr1chu ncar the thyroid gland or thcy may be found in Iny situation in Ihe ned or in the thorlcic cavity. Accessory thyroid tissue has been reported in the hu min by Rodger and Kesten (1$162) and in thc dog by Gc:ii (1$161). 10 MISSOURI AGRICUl.TURAl. [xPUIM!NT STATION LITERATURE CtTED Baird, O. M., A. V. N~lbandov :and H. W . Noreon. 1!n2. Som~ Physiological Cau$C1 of Generically Different R1te5 of Growlh in Swine.). 1'1 .... , Sci. 11:292. BUlt1d,1.. K. 1961. Metabolism of 1' '' in Sheep and Swine. Conference on [he Use of R.dioi$(){opes in Animal Biology and the Medical Sciences. Academic Prns Inc. , New York, N. Y. Caylor, H. D. and C. F. Schlo[lhaucr. 1927. The Thyroid Gland of Swine . ..1 .... /. RK.. ~:"1. Geil, R. G. 1961. inrmhol'llcic Thyroid Gland in 1 Dog. ). /lmt>'. Vtl. /If"'. A ss«. 08:"9. Rodger, W. H. and H. D. Keslen. 1962. Embryologic Buis (or Thyroid Twuc in the H~I. A.w. RK. 1.2:ln. RomKk, F. E. 1963. An1<omy .nd S«rction Rile of [he Porcine Thyroid Glllld. Ph.D. Diucrntion, Univeuiry of Mi$Souri, Columbia, Missouri. Schmidt, J. E., L E. St. Clair and E. F. Reber. 1964. Thyroid Gland Activity in Nor· mal and Surgically Thyroid«lomiz~d Pig'. Federation Proc. 23:108 (ab$U~CI). Si"on, S. ~nd J. D. GrossllWl. 19H. The Anllomy of Ihe Domestic Animals. 4th ed., W. B. SIWldtrS Company. Philadelphia 1nd London. p. ~~S. SI. Cbi., L. E. 19~8. Disosc:s o( Swine (H. W. D\lnne, ed.) low;, St::uc ColJe~ Pres" Ame$, 10WI, p. 26. 

Anatomy of the porcine thyroid

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