Kido T

Kido Tetsuji

木戸 哲二

Kanazawa University Repository for Academic Resources

The Science Reports of the Kanazawa University， Vol. V， No. 2， pp. 77-84， May， 1959 Locαtion of the New Phαrynx in Regenerating Piece of Planαriα By Tetsu日Kmo均(Received February 3， 1959) 77 In the process of regeneration， regenerating part takes at first a much disharmonious form to a remainder of an organism， but in most cas邑sit gradually restores a well proportioned form. This morphological regulation is呂nimportant ev日ntin regeneration. Planaria has a great regenerating power and is able even to undergo simply the regulation by morphallaxis. For e玄ample，the first site of a new pharynx in a regenerating piece is disproportional to the whole at the onset of its development， bu t it takes easily a final position that Is proportional to the organism as a whole. Morgan (100) pointed out that the first position of the new pharynx in a regenerating piece of Planaria has a definite relation to the original region in the worm， from which the piece was taken out. Child (106， '12， '13) stated， moreover， that the more posterior the original rεgion of the piece， the more anterior was the position of the new pharynx in the regenεrating piece. He ascribed this to the regional difference due to the gradient of the physiological activities. Buchanan (127) carried out a more precise experiment by means of estirnating an acculate position of the new pharynx in the piece removed from the various levels of Plzagocata gracilis. According to him the factor which deterrnines the si te of the new pharynx is essentially physiological and quantitati ve in character， lilほ theclaim of Child. Afterwards this gradient conception is stressed by many investigators (Abeloos， '30; Sivickis， '33; Buchanan， '33; Watanabe， '35)， e.g.， head frequency decreases from anterior rearwards in the original worm. However， there remains a question as to whether thεsi向。fthe new pharynx estimated by the previous authors indicates accurately the very same position in which the new pharynx actually begins to develop， because a final position of the pharynx becomes different from the first one due to accornplishment of r号gulation. Therefore， it is required to measure the site of the new pharynx immediately after it is first settled. The present experiment was undertaken with caution for this point. The writer wishes here to express his hearty thanks to prof. Dr. M. Ichikawa of the University of Kyoto， for his encouragernent and reading the rnanuscript. Material and Methods The rnaterial used in the present experiment was Dugesill gonocethala collected in 卦 BiologicalInstitute， Faclllty of Science， Kanazawa UniverslIY 78 T. Kmo the vicinity of Kanazawa City. They wer邑 exclusivelyasexual form 16-18 mm long. H After starvation over a w関 k，animals of approximately 「???? 。目印刷--司M v-一一1---.Ph Fig. 1. 5ch邑m色 showingthe parts to b邑 m邑asur官din the regenerating piece. H; length of the new tissu芭regenerated from the anterior end of the piece. T; length of the new tissue regenerated from th担 posteriorend of the piece. L; total length of the regenerating piece. 民在 dist-ance from the of the anterior new tissue to the middle of a new pharynx. Ph; new pharynx. same sizεwere selected and cut each into a certain number of pieces. The pieces白cceptinga head were cultured respectively in a Petri dish filled with tap water. Caution was paied for detecting the position of the new pharynx as soon as possible and for measuring the lengths of the following portions of a pi居ce:(1) total 1告ngthof the piece Cdesignated as L)， (2) distance from th色 tipof a new head to the middle of a new phary玄 (1'11)，and (3) length of a new tissu巴 regeneratedfrom the anterior cut surface (U) or from the posterior cut one (T)， as sown in Fig. 1. In order to measure as accurately as possible， the specimen was brought under a binocular microscope after fixing it in one per cent solution of hydrochloric acid. The fixation did not at a11 affect the structure of the reg告neratingworm. Occasionally， the hεtεromorphic indi viduals app芭呂日d，but they were excluded from the measurement， for they were unsuitable for the pres告ntpurpose of the experiment. Experi.mental ReslJ!lt.s Experim出1tI. Position of the JZew tharynx in the fourth ザrercuttt旬。Measurements of 50 sp色cimenscoming from each level， exc色ptfor the pharyngeal one (D)， wer告 madεimmediatelyafter the new pharynx became externally visible， or on the third or the fourth day after cutting. The results are summarized in Table 1， but for the sake of convenience， the explanation of the results will be given separately according to the length of theむutpieces. tiece on the third or Table 1. Measur居m叩 tsof the regenerating pi号ceson the third or the fourth day after cutting. EELEI--J竺子! ? | H T L M M/L 会 11211:i:li:;ili:誌 lt器E 0.30 0.24 2.46 0.90 0.36 F 0.30 0.18 2.58 0.90 0.34 G 0 . 24 3 . 18 0 . 84 0 . 262L」iL11与にさに三* Numerals in each column represent the average value of the measurements of 50 specimens Loι.'atiol 0.1 tlze .!Ve1u PlzaryJZx in Regeneraii71g Piece 0.1 Plmwrul 79 PωitムフII 0.1 tle配仰 Jうlzarynxin the shρrt Thεheadl合S8animal was cut transversely into seven pi巴cesalong the body a玄is.but the size of each piece was 80mewh旦tdifferent from level to level (cf. Fig. 2 and the upper 6 rows in Table On the third or fourth day after cutting， the piεce8 from the prepharyngeal l'邑gion(Aj7， Bj7 and 号 itldicatedeach a small but distind accumulalion of dark pigment granules at tbe middle point of a p08terrior borせerline betwe告n the old and new tissues，日gardles8of the level from which the test piece was taken. The pharynx was a1 ways found as a semitr呂nspa1'ent8pot just b色hindthis pigment accumulation，呂ndit began to grow gradually into the old tissue. Such mode of appearance of the new pbarynx has previously been reported by Okacla and Sugino ('37)， Okada and Kido ('43). Kido ('52)， wh己主eas anothεr mode of appearance was statecl by Child ('06) and Teshirogi (ノ55)with different species in which the new pharym:: developed from th居Jirst in the old tissue. The site of the new pharynx with r邑spectto the tota1 length of th日 pieceat the time of it8 first app四 rancewas approximatεly the same with one other (0.89 11 Aj7， 0.86 in Bj7 and Cj7)， as can be seen in T且ble1 as the ratio MjL. At that time， both regeneratεs from the anterior and posierior cut surfaces were yet very poor in growth， and their length differed very slightIy， th日 anteriorbeing a llttle longer than the posterior唱 Theeye-spots were harclly disc号rniblefrom outside. Fig也 2. Scheme showing the levels of seγen pieces (A in the worm. Pl壬 originalph-arynx前In the pieces fro吋1the pharyngeal region (Dj7)， the old pharynx occupied the main part of the piece. In the case in which th合 oldpharyn玄 was left uninjured， it was cut apart from its own bas官 (autotomy)，and thrown out of the body. 1'hε ぉewpharynx developed from the base of the atrium. In the casξin which the old pharynx was left without followed by the autotomy， the old one was absorbed gradually to di問Ipp悶 L，and the new 01邑 arosefrom the middle of the atria1 wall on either side. In s11ort， the mode of dev邑loprnentof the new pharyD.x was not uniform due to pres号nceor absence of the original pharynx. 11 addition， ph呂ryngealappe品rancewas more deiayed in the 1ate1' than in the former case. The data measu日dwith resp日ctto the piece D j7 were omitted from the table for the re呂SOIlof this time difference of the pharyngeal app色aranceand consequently the differenc告 ofthe ratio betw記enthe former and the 1a1εr case. In a11 pi巴cesfrom the postpharyngeal region F /7 and Gj7， cf. Fig. 2)， the ne-vv pharynx occurred always i1' the 01d tissue n日arthe anterior cut surface， i.e.， th日ratioMjL of tI1ese piece d邑creasedto 0.36， 0.34 and 0.24 in respεctive piεce coming fron， the anterior to the posterior level of 1:1e worm， and th日 pharyngeal appearance was slightly delayed in comparison with tha1: i:n the prepharyngeal region. 持Alphabetof numerator， A， B or C represents the level in the worm of the test piece taken fr01Tl anterior rearwal'c1s， and denOlninator indicates the nUlutヲerof the cut pieces from the same indiviclual. 80 T. Kmo (b) Positio1Z 01 t/ze 1U!W アnxuz lhe lOlZg In the above experimental 呂田ies，thε piec邑scut out from th企 prepharyngeal r岳民onwεre always shorter than those from th阜 postpharyngealone. Therefore， there will arise a question concerning the above mentioned locality of the n世w pharynx. In other words， wh巴therthe different values of the ratio M/L between the pre渦 andpostpharyngeal piec日sreally refiect the differ色nceof the region of the worm 01' me1'ely result from the differ芭nceof the length of the piece. In ord日r1:0 settle this question， the furth記rexperiment was carried out. For this purpose the long pieces were cut out from th色 pre咽 andpostpharyngeal regions. The length of the piece AB from the prepharyngeal r・egionwas equal to the length of A/7 plu呂 B/7of the shoけ併合間sof the exp巴rimentand likewise the length of the piεce EF from the postpharyngeal r合 was邑qualto the of E/7 plus F /7 (cL Fig園 2). Even in the long pi世ceABア anew pharynx was a1so formed at a posterior bord告rline between th告 newand old tissues as was found in the short pieces. The ratio M/L in this casεwas 0.92 and in the case of the short piece it was 0.89 in A/7 and 0.86 in The long piece EF showed the onset of the new pharyngeal development in the old tissu告白earthe anterior bord告r，just as the respective short piece E and F did曾 Namely，the工atio~在/L was 0.34 in EF， 0.36 in E/7 and 0.34 in F /7 (cf. the lowεr two rows il Table 1). From these facts it is evident that告venif the pieces were different 1n length， so far 昌吉 they w色retaken from the sam母 region， first position of the new pharynx and its mode of appεar呂nceare both nearly the same 1/5 1/4 1/3 Fig. 3. Scheme邑howingthe origins of the piec邑8of half， one司third唱。ne-fourthand one国fifthof the worm. Each piece is tεrmed A/2， D/5 and 80 Ol， and日.g.， D /5 means D region wh在日 th配 worm wa8 divided into five piec色s.1/2 Locati・ul<'ゾ fル?~Ve7U JJ，んdり!;zxin Regeneratz"7zg Fiue' of P!alwria 81 as in the short piece. Furth告rmore，the spεed of regeneration at both ant巴riorand posterior cut surfaces was not at a1 infiuenced， at least for呂五rstfew days， by the length of the regenerating plece. Experiment I. J守山itio!lof t!ze J!ew f'!zωアJl.Tat fiJu，.lel t!ays after ，:utting. In experiment 1. it i8 exhibited that the new pharynx b色ginsto d告velopat a defini te position of the cut piece， so far as the source of the test pieces is the same level in the worm. However， as regeneration goes further， the new ph呂ryn玄 gradual1ychanges i tsposi tion towards th告 middleof the piece. 1'0 know mor邑 precisel.ythis regulation the te8t pi日ceswere cut in different size from the different regions of the animals， as is shown in Fig. 3. In the pieces derived from the prepharyngeal region such as A/3， A/4， Aj5， Bj5， Aj7， Bj7 and Cj7， t11e n例 Tpharynx always began to develop on the posterior line of demarcation between the old and new tissues， reg呂rdlessof the length of the piece. In the piec田 includingth記 wholeold pharyn玄 suchas B/3， Cj5 and Dj7， the new pharynx developεd according to a rule w11ich was described in the previous experiment. When th色 cuttingwas made a littlεbehind the base of the pharynx， the divided pharynx in the respecti vεpiece was throWD out of the body， but the atrium remained in situ. In the cas巴sin which a basal fragment of atrium remained in the piece such as Aj2 and Bj4， the new pharynx developed from this fragment. But， in the cases in which most of the old atrium except for its base was included as in Bj2 or in Cj4， the new pharynx arose from a point where the cut ellds of both sides of the at1'ial wall fused with each other. 1n the pieces coming from the postpharyngeal region such as Cj3， Dj4， Dj5， Ej5， Ej7 and Gj7， the new pharynx made its app巴arancein the old tissue behind the regenerating new head. In short， th芭 positionand the mode of appearance of the llew pharynx w邑requite similar to those in the cas告 wherea worrn was divided into seven pieces in the previous expεriment. At fourteen days after cutting， the specimens were sacrificed and the measurements of the ratio MjL were made with fifty specimen日 in悶 chgroup. But t11e length of the new head (H) and the new tail (T) conld not be measured， because the boundary between the old and new tissues regenerated from the cut surface became obscure by that time. The shape of the new head and tai1 approached nεarly to the normal 82 T. Kmo Table 2. M邑asurementsof the regen日 piecesat fourtεen days after cutting. Levels of1I田 2surement(in mm)* Ratio egenerating --------- -'~::-:-~:::/------I pieces L M M/L ( A/2 5.46 3.30 0.64 1/2 1 -，l B/2 5.58 2.34 0.40 2.28 1.14 -c函trOl----r← 一一一一一 --_._-， ----一一一一14.32 ヴ08 0.50 盟主 anim呈よぷ.，一一一一一一一一一一一一一一|????????? ?? ?? ?? ?? ?? ?? ????、? ? ? ? ? ?〈? ? ? ?? 。?? ?，? ??????????B/7 C/7 1/7 D/7 E/7 F/7 4.32 5.16 4.32 3.60 4.20 4.14 5.08 4.26 2.64 2.46 1.86 2.28 2.22 1島981.86 2.58 2.28 0.61 0.48 0.43 0.63 0.53 0.48 0.46 4.44 4.38 4.62 4.74 2.04 2.28 2.58 4.31 2.58 2.28 2.16 2.28 l哲81.50 1.44 1.64 2.16 1.38 1.32 0.61 0.53 0.49 0.48 0.41 0.73 0.65 0.63 0.50 0.54 0.58 0.50 持Numeralsin each column represent the average value of the measurements of 50 specimens. D:i.seassJ.l!lK1! As to the ini tial s1 tεof the new occurring in the planarian regenerating piece， Buchanan ('27) found with Plzagocata ・tisthat it is more posteriorly located in th巴 piecetaken from the morf' anterior level of the worm， and it 1S nothing to do with the length of the piece. Child and his school elucidated this fact as a phenomenon which arose according to the physiological gradient existing along the antero-posterior body axis. However， the measurernents in the present experiment at the time of the first appearance of th告 newpharynx reveal忠d that Child's elucidatioll based on the Buchanan's report is not appHcable to our material Dμgesia g問。cethala.In our species， the n号w pharyngeal formation occurs on the posterior 1ine of d告rnarcationbetween the old and n色w tissues of the test piece， reg呂rdlessof the level of the pi色celocated in the original worm， so far as it lies in the prepharyng閃 region.1n the postpharyngeal pieces， this pharyng開 1forrnation always appears in the old tissue at a definitely distant from the tip of the n母w h担adand not at a point that would b色 expectedfrom Locαtio刀ザ t!leNe11J P，加り'nxin Re/Jel.山守的'JZ，gPiece 0/ Pla71ari・a 83 Buchanan's experiment As the regeneration proceeds on， thεnew pharynx is found nearer and nearer to the middle of th己 regeneratingpiece (cf. Table 2). Therefore， the pharynx seems to shift its position cephalad in the prepharyngεa1 piece， but caudad in th色 postpharyngealpiece. Such seeming shift of th邑 pharyngealposition is always recognized in every piece rεgar・dlessof its origina1 length. As to the cause responsible for this seeming shift we can point out the followings : 1) the new pharynx actually grows towards the middle of the test piece during the process of regen巴ration，2) the rate of regenεration differs between the anterior and the posterior cut surface， 3) the morphological regulation occurs by morphal1a玄isthroughout the whole regenerating piece. The first possibility is evidently observed， but not so strong as to affect the measurement value. If th邑 secondis probable， the regeneration in the prepharyngeal pieces has to proc田 dmore rapidly 01' to continue longer at the posterior cut surface than at the anterior one， and jlt'ce ZJers:!-in the postpharyngeal piece. Measurements of the postpharyngeal pieces on the third or the fourth day of regeneration are favourable to the view of thi8 regeJzeratioJZザeed叫がre71ceat the cut surfaces， but those of the prepharyngeal piece8 are not necessarily favourable (cf. Table 1). H and T m日asurementsare impossible later， but it i8 likely that the duration of regeneration differs between the ant日riorand posterior cut surfaces. Concerning the third possiblity， most of the inv思stigatorswho studied microscopically Planarian r告gεnerationdemonstrated that the embryonic cells migrate from the old parenchymatous tissue to the cut end to form a blastema. The migration of such cells is not only favourable to th告 blastemaformation， but a1so to the remoulding of the regenerating piec告。As is shown in T、able2， the sit告 ofthe pharyn玄 indicatedin tεrms of the ratio MjL at fourteen days after cutting shows gradual di妊erencein every group， i. e.， it lies the more posteriorly in the piece taken from the more anterior level of the worm. In the piece from the pharyngeal region， itwas found that the regeneration of the new pharynx proceeds exclusively from the 乱tria1 wall. While in the pre-and postpharyngeal pieces thεnew pharynx was estabHshed from the material other than atrial. What is the source of the new pharynx? Child and Watanabe (135) Summary 1. Headless body of Planarian DUiiesia gOllocejlhala was cut into seven pieces， and a 84 T. Kmo comparison of regen邑rationwas mad色 interms of th居住ngthof the following parts m告asur官d at the time when the new pharynx first appeared， or on the third or the fourth day afterむutting; 1) total length of th世併記ce(L)， 2) distance from the tip of the nεwh回 dto the middle of the new pharynx (M)， 3) 1邑ngthof the new hεad (H) and 4) length of the new tail (T). 2. Ther邑 isa distinct difference in the ratio M/L between the pre-and postpharynge呂lpieces， but no difference ¥vas found so far a呂 thepiece comes from the same pre-or postpharyngeal region. It is a rule that the new pharynx appears always atthe middle point of the posterior border line betw邑nthe new and old tissues in the pr記ph呂ryngealwhile it occurs εxc1usively in the old tissu邑 behindthe r邑generatingnew head in th告 postpharyngealpi色ce白 Inthe ph旦ryngealpiece， i t isderi ved from the celles of the old atrial walL 3. Measurements at fourteen days after cutting indicate that the morphological regulation occurs in duεcours日 withdiff芭rentialfat冶 alongth邑 anteropost日rioraxis of the original body. Reference畠Buchanan， F.V¥人 1927.Jo口r.Exp. 2001.， 48， 6官。Child， C.M.， 1906. Arch. EntwIViech. Org.， 20， 380 Child， C.M.， 1912. Jom¥Exp. Zoo1.， 13， 103. Child C. M. 1913. Arch. EntwMech. Org.， 37， 108. Child， C.M. and Y. Watanabe.， 1935. Phys. Zoo1.， 8， 1.Kido， T.， 1952. Ann. Zool. Jap.， 25， 383. Morgan， T. 1し 1900.Arch. EntwMech. Org.， 1仏48Okada， Y. K. and H. Sugino.， 1937. Jap. Jour. Zool.，乙 373Okada， Y. K. and T. Kido.， 1943. Jour. Fac. Sci. Tokyo Univ.， 4， 601 Stevens， M. l¥ι，1907. Arch. Entwl¥1ech. Org.， 2<t， 350. Teshirogi， W.， 1955. 2001. Mag. (in japanese)， 64， 2骨4.

Location of the New Pharynz in Regenerating Piece of Planaria

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Location of the New Pharynz in Regenerating Piece of Planaria

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