Yashika, Kanji

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RIGHT:URL:CITATION:AUTHOR(S):ISSUE DATE:TITLE:Studies on the NeurosecretorySystem in Apterygota (I) :Histological Observation on theCorpus Allatum andNeurosecretory Cells inCtenolepismaYashika, KanjiYashika, Kanji. Studies on the Neurosecretory System in Apterygota (I) : HistologicalObservation on the Corpus Allatum and Neurosecretory Cells in Ctenolepisma. Memoirsof the College of Science, University of Kyoto. Series B 1960, 27(1): 1-71960-07-25http://hdl.handle.net/2433/258165MEMorRs oF TI{E CoLLEGE oF ScxENcE, UNIvERslTy oF KyoTo, SERIEs B,            Vol. XXVII, No. 1, Articie 1 (Bio!ogy), 1960Studies on the Neuresecretory Systell} iR Apterygota   I. Histological Obse}"vatioR on the Corpus Allatum       and Neuroseeretory Cells in CtenolePismaBy          Kanji YASHIKACollege of General Education, Osalca University        (Received june l5, 1960)   A wealth of studies have been carried out concerning the corpus allatumof the pterygotous insects from the cytological, histoiogical and also experi-rnental points of vlew. But so long as the apterygototts insects are concerned,no literature is availab}e, except for those of ffANsTRoM (1940, 1942) andL CAzAL(1948). CAzAL (lescribed the occurrence of the neurosecretory cells and thecorpus allatum in some apterygotous insects, especially iR IaPNx.   A few years ago I had a lucky chance to fiRd the corpus allatum of aJapanese silverfish, CtenolePisma villosa, when I was studying its neurosecretorysystem. The present paper deals with the cytological and histological observa-tion of this organ and the neurosecretory system aloRe, the physiological Åíunc-tioR of the corpus a}}atum being described elsewhere.    I wish to express my hearty thanks to Prof. Mamori icmKAwA, theUniversity of Kyoto, for suggesting this problem and foy critical yeading of themanuscript. Thanks are also due to Prof. Iwane SATo of the Osaka Universityfor his helpful advice.                         Material and Metheds   The adults of Cte".olept sma villosa rneasure 9 rnm }ong on the average. TlteyIive mostly on the starched paper and are found in book-cases and store-roomsall the year rouitd. The specimens were each cut into the anterior and posteriorhalves iR order to facilitate rapid penetration of the fixative. As the fixativeBouiN's or CAR.Noy's fiuid was mostly used. After fixation, the specimens wereimmersed in methylbenzoate-celloidin mixture') for about 48 hegrs (DEMEREc,1950) in order to soften the chitinous hard parts of the body. Sections werecut at 5 micra, transversely and Iofigitudinally, using the routine parathRtechnique, and stained, in generai, with DF.LAFmm's haematoxyl2n and eosin.    1) Methy}benzoate plus celloidin (99:1).2 Kanji YAs-IKABut GoMoiki's chrom-kaematoxyliB o.B.d phloxin $tain (GoMorti, 1941> was alsoappiied to the mateylcn.1 fixed in BouiNke fiuid, after oxidation iR perrnanganatesolution. This stain was proved suitable to revertc.1 the Reurosecretory substaRcesin tlte cells.                               ebservation   Neurosecretory celts. There occur two kinds oÅí neurosecretory cel}s in thebyain, oRe is the medial neuyosecretory celis and the other lateral neurosecretorycelis.    The medial neurosecretory cells are divided iRto two gyoup$, both of whichare found on either side of the median plane of the protocerebyum. ORe groupis situated on the medial, dorsal surface of the brain as a small protrusioR thatis composed of about fifty ceils (MNCI iR Figs. 1 and 2a). ']rhe protrusioR isencapsuled witk a connective tissue. The cells are spherical about ten micrain diaraeter, and some of them are founcl to contain, in cytoplca_sm, many granuleswhich are stained deep blue with chrom-heamatoxyliR (Fig. 2b). These neuro-secretory cells sencl a Rerve to the brain i(s is indicated witl} an abbreviationof Nlb in Fig. 2a. The other group liesamidst the cells of braiR near the entranceof thi$ nerve into the brain, and it comprises oniy two acidophilic cells (MNC2in F2gs. 1 and 3).    A fine nerve coming from these cells joiRs together wkh the nerve justmentioRed to make the medlal nerve which crosses the same nerve of the op-posite side on the way to the post-ventral part of brain, where it leaves thebrain to innervate the corpus cardiacgm and doysai aorta (Nl in Fig. 1).    TIke lateral neurosecretory cells can be distinguished as a group of threecells which are situated some 50 micra apart from the mediaR plane of the brain(LNC in Figs. 1 and 5). Each cell is large, measuring 25 micra in diameter.The cytoplasm of it is ufistainable with both of the acidic ancl basic dyes, anddevoid of any kinds of droplets ancl granu!eq.. The nerve fibeys of these cellsieave the byain from the post-ventra} part of the same s2de for the corpuscard2acum. This correspoRds to the Iateyal nerve of other insects (N2 in Fig• 1)•    Aortic •iterve and corPus cardiacum The medial and the lateral nerves oReach side gather togethef immediately after they leave the brain. Thls com-posite nerve may be referred to as nervus corporis cardiacl, but tke maindestination of it ls not the corpus cardiacum but the aorta. Theyefore, it willbe better to call it the aortic nerve. The aortic nerve runs bacl<wards, throughthe corpus cardiacum, along the lateral wall of the aerta up to the junctionpoint of the aorta and the heart. The corpus cardiacurn receives fine fibersramified from this nerve within it. It must be .etressed here that maRy con-spicuously stained blue dropiets and a few red ones are found iR this aorticnerve. This fact suggests that the aortic nerve serves as a pathway of theneurosecretory substances produced in the neurosecretory cells in the brain.               Studies on the Neurosecretory System in Apterygota, I 3   The corpus cardiacum is skuated immediately behind the brain. It is aspherical body about 30-35 micra in diameter afid is composed of some twentycells, the cytoplasm of which shows very poor aMnity for both basic and acidicdyes. Stainable droplets can not be seen in aRd beÅíween the cells (Fig. 6)•The situation seems to differ muck from that of the winged insects in whichmany droplets can be demonstrable in various species.   CorPus aggatu7n. The position of corpus allatum is rather different fromthat of Pterygota so far informed. This organ is located at the base of each          N2 Nl MNCI :•IITCL) LNC l'6 N3 AO                       CA N5 N7        Fig. 1. Diagram of the neurosecretory system and corpus allatum in           CtenotePisma viltosa.              MNCI, rnedial neurosecretory cells in a protrusion of the brain;           MNC2, rnedial neurosecretory cells imbedded in the brain tissue;           LNC, ]ateral nellrosecretory cells; CC, corpus carditacum ; CA, corplls           allatum; AO, aorta; Nl, medial neurosecretory nerve; N2, 1(ateral           neurosecretory nerve; risl3, aortic nerve; N4, nervus corporis allati;           N5, an upper branch of the maxillary nerve ; N6, gastric nerve ; N7,           maxillary nerve; FG, frontal ganglion; HG, hypocerebral ganglion;           FOG, fore-gut; MG, mid-gut; SG, suboesophageal ganglion; TG,           thoracic ganglion.maxilla as a sma}l body of about 35 micra in diarneter (CA in Flgs. 1, 7 and 8a).It con.vists of about fifty cells arranged into a vesicle. Sometimes the cavity ofthe vesicle is fi!Ied with a colioidal substance which takes blue dye whenGoMoR.i's chrom-haematoxylin and phloxin stain is applied. The cytoplasm ofthe cells is stained red wkh pkloxin, ancl contains neither vacuo}es nor graRuieswhithin k (Fig. 8b).   Tke corpus allatum is innervated by two nerves. One is, as `alluded inthe above comment, a small branck of nervus corporis cardiaci, separating4 Kanji YAsl-IIKAitself Rear the point where the medial aRd latera} neurosecretory nerves jointogether. This nerve runs thro"gh muscles to reach the surface of the corpusallatum (N4 ln Fig. 1), and, therefore, it raay be equivalent to nervus corporisallati of the other iRsects. Indeed, iR one case a smail droplet stained blue isobserved distinctly in tliis nerve (Fig. 9), although such droplets weye ftotobserved in other cases. The other nerve of the corpus allatum is an upperbranch of the maxillary nerve which cornes from the suboesophageal ganglioR(N5 iR Fig. 1). These two nerves distribute over the surface of the organ anddo Rot enter within.                                Diseussion    It has been revealed by the present observation that the meciial neurosecretorycells of aR apterygotous silverfish, Cte•nolepi. sma viltosa, are differentiated into twogroups, one group mal<es a small spherical body, protruded frorn the brain surface,and the other group is imbedded in the brain tissue. This situatioR of the medialReurosecretoyy cells bears a close resernblance to the appearance of the samecells in the other apterygotous lnsects, Petrobinfn maritima, reported by CAzAL(1948), but differs much from tkat of most kinds of the pterygotous insects inwhich the cells aye always found imbedded in the protoeerebrum. Accordingto my embryological investigation of the present insect that will be publishedin a separate paper, the protxusion of the neurosecretory cells can not be seenuntil a few days after hatching. It is, therefore, evidently a post-embfyonicforrnation.    No l<nowledge of the functional role of the lateral neurosecretory cells ofthis wingless insect ltas yet been gained. As is alreacly maentioned, there areno v2sible signs which demonstyate the secretory function of tke cells becauseof the lack of any stainable materiais wlthln the cytoplasm and the latexalnerve as well. Since, however, the lateral nerve is a part of the aortic nerveand runs backwards together, it is likely, but not pyoved, that there is a func-tional relationship betweell this group of cells and the Reurosecretory system.CAzAL (1948) has already reported a qulte similar topography of the medial andiateral neurosecretory nerves in Petrobius and Letrismina. The fact that bothtlie blue and red droplets in the aortic Rerve diminish themse}ves gradually asthey travel backwards seems to indlcate these stainable substances aye discltargedthrough this nerve into the aorta on the way of their rearward migratlon.But it is not sure whether the neurosecretory material is stored in each nerveterminal ending and then released or it is liberated before it reaches theterminal ending. This may be a device to fit for tke lack of the intimateconnection between the corpus cardiacum anci the neurosecretory Rerve, orcentyarily, it will be the original form to release the secretory material beforethe storage ftmctien of the corptts cardiacgm does develop in fgture phylogeny.Studies on the Neurosecretory System in Apterygota, I 5At any rate, the fact that the stainable substance cannot be detected in thecorpus cardiacum in Ctenolepisma wili favour either view.    In most pterygotous insects, the corpus allatum is situated in the regiondorsal or Iateral to the oesophagus, whereas in Ctenolepisma the organ is locatedat the base of maxilla, as is already mentioned. It is due, in my opinion, tothe fact that the ectodermal rudiment of the corpus allatum invaginated firstfrom the maxillary base can not migrate inwards, but it stays close to its motherlayer, in spite of the same origin as in tlte pterygotous insects. It seems quiteprobable that Åíhis exceptional locatioR of the organ has concealed itself fremdiscovery for a long time untll now. Tlte colloidal substance iR the centralcavity of the corpus aliatum seems to be secreted from the surrounding cells.We Iack the evidence enouglt to assume that the colloidal substance in tkecentral cavity is an accumulation of the neurosecretory mateyial transferred viaaxons fyom the neurosecretory cells 2n the brain, as k is the case in someLepidopterous insects (IcHiKAwA et al., 1959). I am rather inclined to surmisethat it wil} be equivalent to the juvenile hormone secreted frem the allatumcells Shemselves. However, there remains a possibility that there is somerelationship between the neurosecretory cells and the corpus a}latum, since thetwo are conRected, as ift pterygotous insects, by a small branch of the neuro-secretory nerve.                                Sumrnary    1) The corpus allatum and the Reurosecretory system of CtenoJepisma werestudied from the histological view point.   2) The medial neurosecretory cells on each side are divided into twogroups; one is a smal} protrusion of the surface of brain and the other isimbedded in Åíhe brain t!ssue. Lateyal Reurosecretory cells are distinguished asa group of three large cells unstainable wlth basic and acidic dyes.    3) The nerve fibers of the medial aRd lateyal neurosecretory cells jointogether shortly after leaving the brain and ruB backwards along the lateralwall of the aorta.    4) The corpus cardiacum 2s a small spherical body situated behind thebrain. It is innervated by some fine Rerve fibers branching from the aorticnerve, when the latter passes through this organ. No droplets can be seeRbetween the cells of this organ.    5) The corpus allatum is also a spherical body, situated at the base ofmaxil}a. It is inRervated by two nerves; one is a branch of the neurosecretorynerve and the other is abranch from the suboesophageai ganglion. It is dithcultto trace the neurosecretory mateyial to this organ.6 Kanji YAsi-mcA                                 ReÅíereneesCAzAL, P., 1948. Les glandes endocrines retre-cerebrales des insectes (etude morphologique).       Bull. bioL, Suppl., 32 : 1-227.DEMEREc, M., 1950. Biology of Drosophila. I ew York, john Wlley & Sons.GoMoRI, G., 1942. 0bservation with clifferential stains on human islets of Langerhans. Amer.       J. Path., l7: 395-406.HANsTR6M, B., l940. Inkretorische Orange, Sinnesorgane und Nervensystem des Kopfes       einiger Riederer Insektenordnungen. Svenslsc. Vet. Handl., 18 : 3-265.       I942. Die Corpora cardiaca und C. a}lata der Insel{ten. Biol. Gen., 25: 485-531.Ic}iiKAwA, rvl., & J. )islismn"suTsuJi-Uwo, l959. Studies on the role of the corpus allatum       in the Eri-silkworm, Pltilesantta cyi•tthia ricini. Biol. Bull., l16 : 88-94.---  -- & S. TAi<AHAsHI, 1959. Study on the endocrine activity of Bombyx-allatum in the       diapausing Philosamia-pupa. Mem. Cell. Sci. Unlv. I<yoto, Ser. B, 26 : 249-252.PE;LuGFELDER, O., 1937. Bau, Entwicklung und Funktion der Corpora allata und C. cardiaca       von DisciPPtts morostts BR. Z. wiss. Zool., 149 : 477-512.-t--tt..t.t.---.t........ 1938. Untersuchungen Uber histologischen Vertinderungen und das Kernwachstum der       Corpora allata von Termiten. Z. wiss. Zool., 15e: 451-467.-tt .tt.t..tt.t...t..t ..__ 1952. Entwicl<lungsphysiologie der Insekten. Leipzig, Akad. Verlag. Geest & Portig       KTG.Sc}iApkRER, B., 1952. Neurosecretion. XI. The effects of nerve section on the intercerebralis-       cardiacum-allatum system of the insect Le•ttcoPltaea ?naderae. Biol. Bull., le2 : 261-272.THoMsEN, E., 1942. An experimental and anatomical study of the corpus allatum in the blow-       fly Call'tPhora erytl'irocePltala ME!G. Vidensk. Iv{edd. dansk. naturh. Foven. Kbh., 106:       319-405.ToyAMA, K., 1902. Contributions to the study of silkworms. I. On the embryology of the       silkworm. Bull. Coll. Agric. japan, 5:73-117.Fig.Fig.Fig.Fig.Fig.Fig.Fig.                     ExplanatieR ef Plate I2a. Longitudinal section of the brain, cut somehow obliquely through the protrusionsof both sides. Ml Cl, medial neurosecretory cells; Nlb, nerve fibers of MNCI.2b. One enlarged cell ef MNCI $howing inany blue droplets in the cytoplasm.3. Longitudinal section of the brain slaowing the medial neurosecretory cellg. imbeddedin tlte brain tissue and fusion of nerve-fibers ceming from the respective group ofthe neurosecretory cells.MNC2, medial neurosecretory cells ; Nla, a fine nerve of MNC2 ; Nlb, nerve of MNCI.4. Transverse section of the brain showing the lateral neurosecretory cells.LDi<IC, lateral neurosecretory cells.5. Transverse section of the head showing the cut ends of medial and lateral nervesready to join together.Nl, medial nerve coming from MNCI and MNC2 ; N2, lateral nerve arising from LNC ;AO, aorta; B, brain;SA, dorsal salivary gland;FOG, fore-gut.6. Transverse sectign of the head showing both af corpera cardiaca.N3, aortic nerve with many stained droplets; AO, aorta; CC, corpus cardiacum; B,brain; HG, hypocerebral ganglion; FOG, fore-gut.7. Transver$e section of the head showing the position of the corpus allaturr}.Fig.Fig.Fig.          Studies on the NTeurosecretory System in Apterygota, I 7CA, corpus allatum; MX, maxilla; SG, suboesophageal ganglion;SD, duct of theventra} salivary gland.8a. Longitudinal section of the head showing the situation of the corpus al!atum.CA, corpus allatum ; MN, mandible ; MX, maxilla.8b. Enlargement of the corpus allatum with stainable colloid in the central cavity.N5, upper branch of maxillary nerve innervating the corpus allatum.9. Transverse section of the head through the cerpus allatum showinga droplet innervus corporis allati. This is an exceptional case in which a blue droplet is ob-served in N4.CA, corpus nllatum; N4, nervus corporis allati.Mem. Coll. Sci., Univ. Kyoto, Ser. B, Vol. XXVII, No. 1 Pl. I1'cc).ji)/•,v'fa•S.ul,,.IA•vbj ;tk,L  eW e.  501,t ... sOlltC." .,, rij31' t'-st"' -tc:..'.ditisEL,cctw, •A."FOGqs'' h- 5.  t S1 v6'7

Studies on the Neurosecretory System in Apterygota (I) : Histological Observation on the Corpus Allatum and Neurosecretory Cells in Ctenolepisma

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Studies on the Neurosecretory System in Apterygota (I) : Histological Observation on the Corpus Allatum and Neurosecretory Cells in Ctenolepisma

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