Morphology of the embryos at germ disk stage in Achaeranea japonica (Theridiidae) and Neoscona nautica (Araneidae)

5 Pages·1993·1.8 MB·English

by  H Suzuki

MORPHOLOGY OFTHE EMBRYOS ATGERM DISKSTAGE IN ACHAEARANEA
JAPON1CA (THERIDHDAE) ANDNEOSCONA NAUTICA (ARANEIDAE)
HIROHUMI SU2UKI ANDAKIO KONDO
Su7.uki7 H. and Kondo, A. 1993 11 II: Morphology of ihe embryos, at germ disk siagc in
Achaearaneajaponica (Theridiidae) and Neoscona naniica (Araneidae). Memoirs ofthe
QueenslandMuseum33(2»: 645-649 Brishane. iSSN0079-8835.
Embryos atthegerm disk stage were investigated by electron microscopy in Achaearanea
japonica (Theridiidae) and Neoscona naniica (Araneidae). In both spiders, the germ disk
was composedofspherical cells, which hadalmost nolargeyolkgranules. In the innerpart
of the embryo, several large yolk granules were packed by cell membrane with various
organellesandglycogencranniessimilarlytolycosidspiders. InAchaearaneajaponicathere
were very flalcellswhichpossessedseveral largeyolk granules in thesurfaceregionwhere
the germ disk was not formed. In Ncosrrma nuuiica cells were not observed in that region
at all, so the packages oflarge yolk granules were exposed directly to penvitelline space
The araneid type can be distinguished from Ihe agelenid and theridiid type-
DieEmbryonenvon,4f hiuaruneajapifn!i-iiiThcT\d\\diic)undN^(n' OftQnaniica[Araneidae)
im Stadium dcr Kennscheibc wurden millels des Elcktroncnmikroskops untcrsucht. Die
Kcimscheiben der beiden Spinnen bestanden aus spharischen Zellen, die groBe
Dollcrkomchen nur selten haltcn. In dem inncrcn Ted von dem Embryo wurden manche
groBen Dotterkdmchen mil verschiedenen Organellen und Glykogenkornchen von dcr
Zellmembrangepackt, wie im F;ille vonden lycosiden Spinnen. Im Falle vonAchaearanea
japonica gab es feehf llache Zellen, die manche grotton Dollcrkomchen batten, in dent
oberriachlichen BcZtrfc, wodie Kcimscheibe nicht gehildel wurde- Im Falle von Neoscona
naniica wurden die Zellen in dem Bc^irk schlicBlich nichl beobachl. also waren die Paeke
ten OouerW-mchcndireki inder PeriviiellinhohlcentbloBt. DeranmeideTypmBOB
sich von dem agelemdeu Typus und dem iheridndcn Typus unterscheiden. \J$pideK
Achaearanea, Neoscona, embryo, germ disk, morphology*
ftirohUmi SHZtiki and Ak'tO Kondo, Department of Biology, Faculty of Science. John
University. 2-1. Miyawa 2 chome. hiwahoshi-sht, Chiha 274, Japan; 29October. 1992.
Three types ofgerm disk formation are known on the germ disk region and few cells remain on
in the embryos of spiders In the most common tbeotherhemisphere(Montgomery, 1909).Inthe
type known in Agelenidae, the germ disk is thirdtype found inmany Araneidae, aripappears
formed on a hemisphere ofthe egg as the result
of transformation of squamous blastoderm cells in the blastoderm, so the yolk mass is exposed
in this region into spherical cells. Egg surface of (Sekiguchi, 1957).Then all blastodermcellstake
thfi other hemisphere is covered with squamous part in germ disk formation, andany cellsarenot
cells (Holm, 1952). In the second type known in observed in theregion wherethegermdisk isnot
Theridiidae, the most blastoderm cells converge formed. A comparative study of the spider
embryosatgermdiskstagewascarriedoutunder
lightmicroscope (Kondoand Yamamoto, 1975).
Tbe study ofgerm disk formation underelectron
microscope was executed in lycosid spiders,
whose germ disk formation is the agelenid type
(Kondo, 1969, 1970). We had to examine
whetherremainingcellsconnecteachothcrornot
in theridiid type and whether extreme thin cells
exist or not at the superficial region where the
PjIaGp.onI.iTchae(eam)braynodatNgeeorsmcdoinsaksntaaugteiicnaAc(hba).eanIn A. germdisk isnotformedinaraneidtype. Inpresent
iaponica a u-^cvlK;»refoundon regionwhere germ study, electron microscopic investigation of the
disk is not formed, inN. mmiica, exposed yolk n embryos at germ disk stage was carried out in
is foundon thai region. Scalc=0.2mm. Achaearanea japonica and Neoscona naulica.
646 MEMOIRSOFTHEQUEENSLANDMUSEUM
ps
&
r*=
•
FIGS. 2-8. 2. A. japonica. Peripheral region of two germ disk cells. (0.5jxm.) Arrowhead: Desmosome-like
structure, 3. Amid-body. Many microtubules, (ljxm.)4. Agermdiskcell. Maincomponentsofcytoplasmare
fatty granules (fg) with medium electron dense matrix, and no large yolk granules. (lOjun.) n: nucleus, ne:
nuclearenvelope. 5. Mitochondria havehighelectrondensematrix andthecristaearefound faintly. (0.5jxm.)
6. Cup-shapedmitochondrion. (0.5jim).cm:cell membrane.7. Ring-shapedmitochondrion. (0.5jim.)8. Fatty
granule (fg) lacking complete limiting membrane, but partly enclosed by smooth-surfaced endoplasmic
reticulum (er). (ljxm.)gg: glycogengranules, m: mitochondria, ps: perivitellinespace. Scalesinparentheses.
,
EMBRYOMORPHOLOGY IN TWOSPIDERS Ml
MATERIALS ANDMETHODS Mitochondriahada highelectrondensematrix,
and thecristae were foundfaintly (Fig, 5). Many
Achaearaneujaponica(BbsenbergandStrand) figures of mitochondria showed oval or a
(Theridiidae) and Neoscona naatica (L. Koch) bars, and several showed cups (Fig. 6) or rings
(Araneidae) were used here. In A. juponica, the (Fig. 7 i
eggscollectedinAugustwereused. InN.nautica Smooth-surfaced endoplasmic reticula were
the eggs laid in glass tubes at laboratory were often found enclosing fatty granules (Fig. 8)
used.Theobservationoftheliveeggswascarried Rough-surfaced endoplasmic reticula were no*
ou! in liquid paraffin, where the opaque chorion observed.
became transparent. The eggs were fixed for 3 Typical Golgi bodies wererare. Vesicles were
hours at 4DC in 2% paraformaldehyde and 2.5% generally observed in the cytoplasm. The
M
glutaraidehyde solution in 0.1 phosphate buff- glycogengranules,0.1p.mindiameter,werevery
er, pH 7.4, containing 0.2M sucrose Through high electron dense, and scattered.
fixation, theeggswerecut inhalfwithatungsten "Thesuperficialregionwherethegermdiskwas
needle.Afterrinsingmorethanonehourwith the notformed wasoccupiedby remainingflatcells.
same buffer containing 0.2M sucrose, the These cells were about lOOftm in length, abou!
sampleswerepostfixedforonehourat4°Cin2% 25u.m in thickness at the central part, but often
i'smic acid in 0.1M phosphate buffer, pH 7.4, less than Iprn near the peripheral one (Fig. 9).
withoutsucrose. Afterrinsingwiththesamebuff- The diameter of nuclei was about 13p.m. Des-
er without sucrose, samples were dehydrated in rnosome-Iike structures were observed between
rthanol series, transferred to propylene oxide. remaining cells (Fig. 9).
and embedded in Quetol-812. Ultrathin sections Several large yolk granules occurred in these
were cut on a ultra-microtome, LKB-4800, remaining cells. The largest yolk granule was
sunned with uranyl acetate and lead citrate, and 2G>m in diameter. Vesicles were sometimes ar-
examined underHitachiHU-12Aelectronmicro- ranged along thelargeyolkgranules (Fig. 10).
scope. Thick sections were prepared simul- The interioroftheembryowas filled with yolk
taneously, and stained with methylene blue for packages composed of several large yolk
light microscopy granules, various organelles and glyc
granules, and enclosed bv cell membrane -
RESULTS id.
ACH*$ARJlHBAMt'OMCA (feast \ntcA
The eggs were spherical and 0.5mm in Ellipsoidal eggs ofA. nausica had longer axis
diameter Typical theridiidtypegermdiskforma- measuring 1,2mm and shorter axis measuring
Lion was observed (Fig, la). At 25°C, the eggs imm. At 23°C\ 45 hours were needed from
took24hourstothegermdiskstageafteroviposi- oviposition toestablish thegerm disk (Fig. lb).
lion. The germ disk was a single layer of spherical
The germ disk was formed as a single layer cells, but the cells piled up in its central region.
composedofsphericalcells,butthecellspiledup The cell diameters were about 45pm, and those
in its central region. The diameter of germ disk ofnuclei were about20pm. Between thesecells,
Cells was about 30pm,. and that of nuclei was there weredesmosome-hke structures but no in-
about 15p.m. Desmosome-like structures were terdigitations.
observed between germ disk cells at the superfi- Various types of lysosome-like bodies were
cial region (Fig. 2). hut interdigitations were not observed (Figs 12-14). Mitochondria often
observed. Mid-bodies wereobservedrarely (pig, crowded around the nucleus (Fig. 15). Several
3). Narrow cytoplasmic bridge connected cells Golgibodieswereobserved(Fig. 16) OthercomA-
adjacent to each other, and contained many ponents ofcytoplasm were similarto those of
microtubules. japanica
The main components ofcytoplasm were tatty No blastoderm cells were observed inthe sur-
granules, 1- 3pm in diameter, with a matrix ofa face region where the germ disk was not foi
mediumelectrondensity (Figs4, 8). The limiting (Fig. 17).
membrane wasoftenobscure.Thegermdiskcell
DISCUSSION
Ad -ilmoM do large yotk granules. Fine yolk
granules, less than 5yun in diameter, were ob-
served. In this study, some cup- or ring-shaped
648 MEMOIRS OFTHEQUEENSLAND MUSEUM
n
16
vm
ne
mitochondria were observed. These types of were figured in embryo of A. tepidariorum
mitochondriawere notreportedin iheembryosof (Suzuki and Kondo, I99l). In N. nautica, many
lycosid spiders (Kondo 1969, 1970). but they mitochondria were found surrounding the
T
EMBRYOMORPHOLOGY IN TWOSl'IDHKS M9
vm- yolkcells. Inthis investigation,detailedobserva-
tion ofyolkcells was not carried out.
The embryo at gemi disk stage in A.japonica
hadveryflatcellswithseverallargeyolkgranules
(Fig. 18). Distinctdifferencesofcytoplasm were
noi observed between spherical germ disk cells
and flat remaining cells. As in A. tepidariorum
(Suzuki and Kondo, 1991), except for the large
yolk granules and extreme flat shape in the
... :,,, ./ ... .-...., remaining cells, the tine structure ofembryo at
germdisk stageinA.japonicawas similartothat
in lycosid spiders belonging to agelenid type.
FIsGt.ageISi.nSAc,hjeampaotniiccafi(gluerfet)saonfdeNm.brnyaoutsicatag(reirghmt)d.isIkn- In ,V, nautica, theyolkpackages were exposed
both spiders, the germ disk iscomposedofspherical directlyto the perivitelline space (Fig. 18).
cells, whichhavealmost no largeyolkgranules. The
LITERATURECITED
interior ofthe embryos is filled with yolk packages
(yp). In A. japonica, there are very flat cells which
possess seveial large yolk granules in the surface HOLM, A. 1952. Experimentelle Unlersuchungcnfiber
region where the germ disk is not formed. In fV Bntwicklung uod Entwickluogsphysiologic
nautica. any cells are not foundinthat region, sothe dL-sS;!;nnciicmbryus.ZoologiskaBidrag Iran Op
ypUt packages are exposed directly to perivitelline psalo 29: 293-424.
space(ps). vm;vitelline membrane. KONLXXA. 1%V.Thefinestructureof"theearlyspider
cmbrvo. The Science Reports of the Tokyo
nucleus. This phenomenon was reported in Kyoiku Daigaku. Section B 207:47-67.
lycosid spiders (Kondo, 1969), In N. nautica, i L.i7fi Morphological study on the spider's
many lysosome-like bodies, described also in eJomubrrnyaolnoifcDccvelellsopatmegnetrelmBdiioslkogsyta2g4e:.2J0a-p2a1.ne(sien
lycosid spiders (Kondo, 1969), were observed, Japanese)
however histocbemica] studies arc needed for KONDO. A. & YAMAMOTO, N. 1975.Comparative
final identification. morphologyon theearlyspiderembryos. Atypus
In both spiders, A. japonica and N. nautica, MONT63G:O1M3.E(RinYJ,apaTn.esHe.) 1909. The development of
interdigilarions were not observed,bill they were Thcridium, an Aranead, up to the stage ofrever-
reported in germ disk region of lycosid spiders lurri.Journal ofMorphology 20: 297-352.
I Kondo, 1970). SEKJGUCHL, K. 1957. Reduplication in spider eggs
Jn the inner part ofthe embryo in both spiders, produced by centnfugation. The Science Reports
several large yolk granules were packed by cell o\ theTokyo Kvoiku Daigaku Section B 8: 227-
230
mgreamnbulreasn.eThweistehsvtarruicotuusreosrgwaenreelldeesscarnidbegdlayscoygoelnk SUZUgKeIr,m'H.di&skKiOnNtDheO,thAer.id1i9i9d1s.pFiidnere,stArcuhctaueraeroafntehae
spheres in lycosid spiders (Kondo, 1969) Since tepiditrionem (C. Koch). Proceedings of
nucleuswasnotobservedinthem,thesepackages AruVopodanEmbryologica! Society ofJapan26:
of large yolk granules were distinguished from 11-12.
MG. 9-17. 9-1 1. A.japonica 9. Extreme Hat shape in peripheral part of remaining cells. A dcsmosoinc-like
structure (Arrowhead) is found between cells. (lu.m). 10. A large yolk granule included in remaining cell.
Arranging vesiclesalongyolkgranule. (0.5u.m). 11. Peripheral part ofyolk package in inner part ofembryo.
Large yolk granules, a ring-shaped mitochondrion (m), vesicles (v). and glycogen granules (arrowhead) are
packed bycell membrane. (1u.m).
12 17. rV. nautica 12. A lysosome-like body includingamorphousmatrix. Aring-shapedmitochondrion(m)is
found. (IjAnt) 13. A lysosome-like body including many small vesicles (lu-m). 14. A lysosome-like body
including several double membranes or myelin-like structure. (lp,m). 15. Mitochondria around nucleus In)
srehgoiwoinnwghneurcelegarerpmordei(sakrirsownhoetafdo)ramnedd.nuAclyeoalrkenpvaeclkoapgeeinceo)m(p1ojsime)d. o16f.lAarGgoelygo)lkbogdrya.nu(l0e.s5^(my)g.),1a7.cSuupp-ersfhiacpieadl
mitochondrion(m),glycogengranules(arrowhead),andvesiclesareexposeddirectlytoperivitellinespace(ps).
(l(im). Abbreviations: fg: fatly granule, fy: fine yolk granule, gg; glycogen granules; ps: perivitellineSpace,
yg; yolkgranule vm: vitelline membrane. Scale lineinparentheses.