Watanabe Yoko

紀要類（bulletin）departmental bulletin pape

Watanabe, Yoko

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

OUTLINE OF MORPHOLOGICAL OBSERVATION ON THEDEVELOPMENT OF TETHY A SERICA LEBWOHL著者 Watanabe Yokojournal orpublication titleThe bulletin of the Marine Biological Stationof Asamushi, Tohoku Universityvolume 10number 2page range 145-148year 1961-03-25URL http://hdl.handle.net/10097/00131112BULLETIN OF THE ~l ARINE BIOLOGICAL STATION OF ASA~!USHI , VOL. X , NO. 2. 1960 OUTLINE OF MORPHOLOGICAL OBSERVATIO 0 THE DEVE LOPMENT OF T ETHY A SERICA LEBWOHL By Yor.;:o WATANABE i!lt ill i:P -T Z oological Laboratory, Faculty of Science, Ocfjanomiztt University, Tol1yo, Japan I:-<TRODUCTION Tethya serica Lebwohl, a tetraxonian sponge lives on the shallow bottom of the sea near the Misaki Marine Biological Station. This sponge is dioecions and fert ilization takes place ectosomatically. In other details the species shows some peculiarities in its developmental processes, which have been described by Kagai 1910 and Knme 1952 their results briefly will be summarized. 1) The unfertilized egg has numerous fine cytoplasmic processes radiating from its surface and when it is fertilized, t he fertilization membrane is elevated and these proceses are taken into the perivitelline space (Fig. 1 a-e) . 2) The surface of the fertilized egg be-comes so sticky that the egg adheres to the substratum. 3) The segmentation of F ig . I . a) U nferti lized egg; Protoplasmic processes radiating from its surface. b-e) F ertilized egg; T he fertil ization membrane elevates gradually and the processes a re spirally twested in (e). f) F irst cleavage; Processes were completely taken into t he perivi-t elline s pace, bu t they still remain as g ran ules. 145 146 Y . 'WATANABE the egg is total and almost equal but there are many variations in the cleavage pattern, which are due to the adhesion of the egg to the substratum. The external changes of this sponge from segmentation to the young form have been described by Watanabe in 1957. This report will deal with the internal changes as observed in serial sections, in addition to the external changes. The writer thanks the staff of the Misaki Marine Biological Station and Pro-fessor Matazo Kume for his continuous direction. Fig. 2. blastula; Thread-li ke processes extend from the surface. An outer cell now extending a thread-like process. c) E mbr yo extended on s ubstratum by p ulling of processes and becomes somewhat fia ttend . d ) Cells m ove out into processes stretching them to form m ulticellular structures. Fig . 3 . a) Longitudinal section of invaginating st age; Fibrous str uctures differentiate in the d epressed region. b) Embryo becomes spherical again and the root begins to form beneath emb ryo. Spicules differentiate in t he center of embryo. c, cl) Two embryos ly ing in contact with each other, they invaginate at contact plane. Fibrous structure a re seen there. DEVELOPMENT OF TETHY A SERIG.Il LEBWOHL 147 OBSERVATIONS 1. External and internal changes to the root-forming stage. Following segmenta-tion, the embryo becomes a solid blastula. In this stage, some of the outer cells of t he blastula stretch threadlike processes (one from each cell) from the surface. These threads extend further and attach to the substratum to which the egg first adhered (Fig. 2 a, b). These cells then move out into the perivitelline space, ex-tending pseudopodia as if they were being drawn by the processes. As a result, F ig. 4. a) Cross section of ten day embryo; Flagellated chambers and framework of megasclers fo rmed. b) Flagellated chamber c) Cross section ; Jncurrent and excurrent cavities are formed between the megasclers . cl) Fifteen clay emb r yo; I ncur-rent ca vities (transparent parts) differentiate between megasclers. e ) Excurrent pore opens near base of root . f) Longitudinal section of 17 clay embr·yo, through excurrent p ore. g) A you nrr spon"'e wi th osculum. (fixed specimen) h ) Longitudinal secti~1 of ~oung sponge. i) Same sp ec imen as t hat in (h); longitudinal section through osculum. 148 Y. WATANABE these processes become wider and other cells enter them, forming multicellular structures (Fig. 2 c, d). As these multicellular processes radiate in various direc-tions, the embryo as a whole becomes somewhat flattened and stretches on the substratum (Fig. 2 c). These processes later unite to form the root. Presently the solid blastula begins to invaginate on the attached side. The cells on this side move inside the embryo, resulting in a depreseion of the surface and fibrous structures differentiate in this region (Fig. 3 a, c, d). These fibers and the processes which constitute the rudiment of the root come together beneath the embryo and form the root. At this time the flattening disappears and the embryo becomes spherical again. (Fig. 3 b). During this time the scleroblasts are differentiated from cells at the center of embryo, and these form the spicules (Fig. 3 b). 2. Radial arrangement of internal structure and formation of canal system. Some of the invaginated cells differentiate into cells which form the flagellated chambers. These are surrounded by small flagellated cells, but the flagella of these cells are not clear with ordinary staining procedures. These flagellated chambers are found here and there inside the embryo (Fig. 4 a). Meanwhile, the spicules, which are being formed in the center of the embryo, grow and radiate in all directions and construct a radial framework of large spicules (megasclers) (Fig. 4 c, d). Cross section of this stage show that the incurrent canals are begining to develop between the megasclers. When the incurrent canals are completely formed, the epidermis is seen to spread voer the outer surface of the embryo, forming their dermal layer, which becomes pierced by a number of incttrrent pores. Inside the embryo, ex-current canals also developed between the megasclers. Each flagellated chamber is connected wHh an incurrent canal by a prosodus, and with an excurrent canal by an aphodus. In such a way, the embryo allows a radical by symmetrical stru-cture (Fig. 4 c, d). The excurrent pore opens at first near the base of the root (Fig. 4 e, f), but afterwards an osculum develops on the upper surface of the embryo (Fig. 4 g, i). Here the current streames out of the sponge. In such a manner, the embryo grows into young sponge (Fig. 4 g, h). LITERATURE NAGAI, M., 1910. On the fertilization of the egg and its cleavege in Tetltya serica (in Japanese). Dobutsugalm Zasshi, 22 : 76-85. KuME, M., 1952. Note on the early development of Tethya serica Lebwohl a tetra:xonian sponge. Nat. Sci. Rep. Ocbanomizu Univ., 3 ~ 63-67. VVATANABE, Y., 1957. Development of Tethya serica Lebwohl, a tetraxonian sponge. Nat. Sci. Rep. Ochanomizu Univ., 8 : 97-104. 

OUTLINE OF MORPHOLOGICAL OBSERVATION ON THE DEVELOPMENT OF TETHY A SERICA LEBWOHL

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OUTLINE OF MORPHOLOGICAL OBSERVATION ON THE DEVELOPMENT OF TETHY A SERICA LEBWOHL

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