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      • 韓國産 미꾸리에 關한 育種·繁殖學的 硏究 : Ⅵ. Histological Changes of Pituitary Gland and Oocytes from March to May Ⅵ. 계절에 따른 암컷의 腦下垂體와 卵母細胞의 組織學的 變化

        姜京來,盧淳昌,尹鍾萬,朴弘陽,李相鎬 건국대학교 동물자원연구센터 1993 動物資源硏究誌 Vol.18 No.-

        1992년 3월부터 1992년 5월까지 자연적인 채광상태에서 溫度를 유지시킨 후 채취된 미꾸리 암컷의 腦下垂體, 肝 및 卵巢 組織의 번식주기에 일어나는 미세구조의 변화를 광학 및 투과형 전자현미경을 이용하여 살펴보고, 이것들의 相互 聯關性을 알기 위하여 본 연구를 실시하였다. 본 연구에서 얻어진 결과는 다음과 같다. 성숙된 개체의 뇌하수체는 수많은 작은 분비과립과 커다란 분비구 및 불규칙한 형태의 과립들이 관찰되었다. 핵소체가 핵막 주변에 위치헤 있는 후기 단계(LMO)의 난모세포가 난황이 축적되는 성숙초기 단계(EMO)의 난모세포로 변형되는 시기를 난황의 형성이 개시되는 시기로 본다. 난모세포가 성장함에 따라 핵소체의 크기와 난황과립의 수가 증가하게 된다. 난황과립은 결정상의 과립으로 난세포질에 치밀하지 않은 상태로 축적된다. 성숙초기(EMO) 및 말기단계(LMO)에 난소는 커지고 투명하며 과립형태로서 색깔이 연노란색을 나타낸다. 따라서 난 내부를 쉽게 관찰할 수 있다. 방사대(ZR)는 성숙초기단계(EMO)에 단층으로부터 입방형태로 변화된다. 과립막 세포와 난모세포로 부터 유래된 미세융모는 난황형성이 진행되는 동안에 성장하게 되며, 방사대의 pore canals의 구멍을 통해서 서로 연결되어 있다. 따라서 외부로부터 물질의 이동이 있게 된다. 난모세포가 완전하게 성숙되어 방사대가 단단해 지면 미세융모는 그 기능이 상실된다. This study was undertaken to understand the development stages of pituitary gland, liver and ovary of Korean loach(Misgurnus anguillicaudatus) under natural circumstances from March to May 1922. Expecially, the light microscopic and ultrastructural changes of ooplasm and follicular membranes of oocytes, were observed by light and transmission electron microscope during the reproductive cycle. In pituitary gland of mature individuals, there were observed a number of secretory granules,large globules, and irregular masses.The vitellogenic phase began as these late perinucleolus oocytes became transformed into early maturing oocytes through the accumulation of yolk. The size of the nucleoli and number of the yolk granules increased as the oocyte growed. Yolk granules were loosely deposited in the oocyte as crystalline granules. Due to the presence of early and late maturing oocytes, their ovaries were enlarged transparent, granular and yellowish in color. Zona radiata change a squamous into cuboid shape in EMO stage. Microvilli from the granulosa cells and from the oocyte grow and make contact with each other in the pore canals of the zona radiata during vitellogenesis, but are withdrawn as the zona radiata becomes more compact during oocyte maturation.

      • Development and ultrastructure of the rigid dorsal and flexible ventral cuticles of the elytron of the red flour beetle, <i>Tribolium castaneum</i>

        Noh, Mi Young,Muthukrishnan, Subbaratnam,Kramer, Karl J.,Arakane, Yasuyuki Elsevier 2017 Insect biochemistry and molecular biology Vol.91 No.-

        <P><B>Abstract</B></P> <P>Insect exoskeletons are composed of the cuticle, a biomaterial primarily formed from the linear and relatively rigid polysaccharide, chitin, and structural proteins. This extracellular material serves both as a skin and skeleton, protecting insects from environmental stresses and mechanical damage. Despite its rather limited compositional palette, cuticles in different anatomical regions or developmental stages exhibit remarkably diverse physicochemical and mechanical properties because of differences in chemical composition, molecular interactions and morphological architecture of the various layers and sublayers throughout the cuticle including the envelope, epicuticle and procuticle (exocuticle and endocuticle). Even though the ultrastructure of the arthropod cuticle has been studied rather extensively, its temporal developmental pattern, in particular, the synchronous development of the functional layers in different cuticles during a molt, is not well understood. The beetle elytron, which is a highly modified and sclerotized forewing, offers excellent advantages for such a study because it can be easily isolated at precise time points during development. In this study, we describe the morphogenesis of the dorsal and ventral cuticles of the elytron of the red flour beetle, <I>Tribolium castaneum</I>, during the period from the 0 d-old pupa to the 9 d-old adult. The deposition of exocuticle and mesocuticle is substantially different in the two cuticles. The dorsal cuticle is four-fold thicker than the ventral. Unlike the ventral cuticle, the dorsal contains a thicker exocuticle consisting of a large number of horizontal laminae and vertical pore canals with pore canal fibers and rib-like veins and bristles as well as a mesocuticle, lying right above the enodcuticle. The degree of sclerotization appears to be much greater in the dorsal cuticle. All of these differences result in a relatively thick and tanned rigid dorsal cuticle and a much thinner and less pigmented membrane-like ventral cuticle.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Development of <I>Tribolium</I> elytral dorsal and ventral cuticles is asynchronous except at certain phases of deposition. </LI> <LI> Exocuticle of the dorsal cuticle contains numerous horizontal laminae and vertical pore canals with chitin fibers. </LI> <LI> Mesocuticle is present between the exocuticle and the endocuticle in the dorsal cuticle but not in the ventral cuticle. </LI> <LI> Both dorsal and ventral cuticles contain an endocuticle consisting of a thick brick (macrofiber/Balken)-type of laminae. </LI> <LI> The dorsal cuticle is four-fold thicker and more sclerotized than the ventral. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

      • SCISCIESCOPUS

        Group I chitin deacetylases are essential for higher order organization of chitin fibers in beetle cuticle

        Noh, Mi Young,Muthukrishnan, Subbaratnam,Kramer, Karl J.,Arakane, Yasuyuki American Society for Biochemistry and Molecular Bi 2018 The Journal of biological chemistry Vol.293 No.18

        <P>Roles in the organization of the cuticle (exoskeleton) of two chitin deacetylases (CDAs) belonging to group I, TcCDA1 and TcCDA2, as well as two alternatively spliced forms of the latter, TcCDA2a and TcCDA2b, from the red flour beetle, Tribolium castaneum, were examined in different body parts using transmission EM and RNAi. Even though all TcCDAs are co-expressed in cuticle-forming cells from the hardened forewing (elytron) and ventral abdomen, as well as in the softer hindwing and dorsal abdomen, there are significant differences in the tissue specificity of expression of the alternatively spliced transcripts. Loss of either TcCDA1 or TcCDA2 protein by RNAi causes abnormalities in organization of chitinous horizontal laminae and vertical pore canals in all regions of the procuticle of both the hard and soft cuticles. Simultaneous RNAi for TcCDA1 and TcCDA2 produces the most serious abnormalities. RNAi of either TcCDA2a or TcCDA2b affects cuticle integrity to some extent. Following RNAi, there is accumulation of smaller disorganized fibers in both the horizontal laminae and pore canals, indicating that TcCDAs play a critical role in elongation/organization of smaller nanofibers into longer fibers, which is essential for structural integrity of both hard/thick and soft/thin cuticles. Immunolocalization of TcCDA1 and TcCDA2 proteins and effects of RNAi on their accumulation indicate that these two proteins function in concert exclusively in the assembly zone in a step involving the higher order organization of the procuticle.</P>

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