Microscopic ovary features of Zebrafish were analyzed. Samples were fixed in Bouin's solution, mounted in parafin and cut into 6-7 µm-thick slices which were stained with Hematoxylin and Eosin (HE), methylene blue and using Periodic-acid Schiff method (PAS). The thin sections in ultramicrotome with the thickness of approximately 0,5-0,7 µm were examined by using Jeol electron microscope following contrasting with Uranyl Acetate-Lead Citrate. The zebrafish was an extremely dynamic organ in which follicles underwent asynchronous development. The oocytes of Zebrafish ovary were observed in various phases. The oocyte development of zebrafish was divided into four stages (primary growth, cortical alveolus, vitellogenic and mature oocyte). Oocyte diameters were observed to vary between 0.,08 mm and 0.76 mm.

In sexually reproducing organisms, primordial germ cells (PGCs) give rise to the cells of the germ line, the gametes. In many animals, PGCs are set apart from somatic cells early during embryogenesis. This study explores the origin of primordial germ cells (PGCs) of the zebra fi sh and examines their morphology during early development (1 st day-15 th day). PGCs were selectively stained by the alkaline phosphatase histochemical reaction and viewed by light and electron microscopy from the time they are fi rst detectable in the yolk sac endoderm. PGCs occurred in the subendodermal space on the syncytial periblast; diff ering from the surrounding endodermal cells. Later the PGCs moved to between the blastoderm and yolk sac and transferred to the dorsal mesentery where they formed gonadal anlage with mesoderm cells. PGCs were easily distinguished from somatic cells by their morphology and low electron density of their nuclei. Under light microscopy, PCGs were rounded with a distinct cytoplasmic membrane.

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Plant growth regulators are the chemicals that are found in plants and produced synthetically. In agricultural applications, plant hormones are used in minor quantities for fixing the problems. In our research, we studied the effects of 2,4 diclorophenoxyacetic acid (2,4D), which is an auxin used in agricultural applications. Auxins are the group that are used most popularly in plant growth regulators. In our study, different doses of 2,4 diclorophenoxyacetic acid are given to zebrafish, and ovarium tissues are observed histomorphologically. We generated one control and three experiment groups from the stock solution. The experiment was carried out in 20 liter capacity complete glass aquarium at 24918C water temperature. After five days of application, fishes were dissected. Histomorphological changes of the ovarium were investigated under a light microscope. A decrease in the number of oocytes in zebrafish ovarium was observed when compared with the control group. Many deformed and underdeveloped oocytes were detected. An increase in the number of atretic oocytes was observed. It was deduced that acute doses of 2,4 diclorophenoxyacetic acid decelerates oogenesis in fishes.

Fine structures of the zona radiata in zebrafish, Danio rerio, is examined and compared. The zona radiata (called as zona pellucid in mammals), is a porous structure located between oolemma and follicle cell epithelium in fish, has various functions. The zona radiata is an inner connection surface that regulates essential transition from follicle cells to oocytes and from oocytes to follicular layer. In this study, it is aimed to examine changeable and distinct structure of the zona radiata during oocyte development in zebrafish, which is a member of teleosts fish family. The structure of zona radiata were examined using light and transmission microscopy. The structure of zona radiata showed a morphological difference among the different species. The zona radiata structure could not be seen under light microscope in the pre-vitellogenic phase, but it was seen as a thin line form at the edge side in the early vitellogenic phase. In the following phases, the tendency to become thicker zona radiata was observed. The existence of microvillus structures, which lie from the zona radiata to follicle cell layer and from this layer to the zona radiata, was observed by means of electron microscope. It was assumed that the oocyte ensures communication between two sides through microvillus structures. Özet:Zebra balığında zona radiatanın ince yapısı incelendi ve karşılaştırıldı. Balıklarda oolemma ile folikül hücre epiteli arasında bulunan gözenekli bir yapı olan zona radiata (memelilerde zona pellusida), pek çok görevi yerine getirir. Zona radiata, granulosa hücrelerinden oositlere, oositlerden foliküler tabakaya gerekli hareketi düzenleyen bir iç alış-veriş yüzeyi gibi düşünülmektedir. Bu çalışmada amacımız, kemikli balık türü olan Zebra balığı (Danio rerio)'nda oosit gelişimi esnasında Zona radiatanın değişken, özgün yapısını incelemektir. Zona radiatanın yapısı ışık ve elektron mikroskobu kullanılarak incelendi. Farklı türler arasında zona radiata yapısı morfolojik farklılıklar gösterdi. Previtellojenik evrede zona radiata yapısı ışık mikroskobunda görülmedi, ancak erken vitellojenik evrede kenar bölgede ince çizgi halinde seçildi. İlerleyen evrelerde zona radiatanın kalınlığında artma gözlenmedi. Zona radiatadan folikül hücre tabakasına doğru uzanan, folikül hücre tabakasından da zona radiataya uzanan mikrovillus yapılarının varlığı elektron mikroskobu ile izlendi. Bu mikrovillus yapılarının aracılığı ile oositin iki yönde iletişimi sağladığı gösterildi.

Bu çalışmanın amacı, İzmit körfezinden avlanan derin su pembe karideslerinin (Parapenaeus longirostris Lucas, 1846) mevsimsel değişimler göz önüne alınarak hepatopankreas ve abdominal kas dokularındaki glikojen, total lipid, trigliserit, kolesterol ve mineral (Ca, Na, K, Fe, Mg) içeriklerini incelemektir. Derin su pembe karidesi İzmit Körfezi'nde en bol bulunan penaeid türü karidestir ve mevsimsel olarak toplanmışlardır. Karideslerin abdomial kas dokuları ve hepatopankreasları laboratuarda serbest glikoz, glikojen, total lipid, trigliserit ve total kolesterol ve mineral içeriklerinin tayinleri için çıkartılmıştır. Ayrıca bu çalışmada dişi ve erkek karideslerin abdominal kas dokularında K, Na, Ca, Fe, Mg elementlerinin seviyeleri belirlenmiştir. Elde edilen verilere göre hem erkek hem de dişi karideslerin metabolik enerji ve fizyolojik aktiviteler için kullandığı temel kaynaklar total lipid ve glikojendir. SummaryThe aim of this study is to identify seasonal variation of biochemical composition and mineral content (K, Na, Ca, Fe, Mg) in abdominal muscle tissues and hepatopancreas of the Deep sea pink shrimp (Parapenaeus longirostris) caught from of the Gulf of Izmit, Turkey. Deep sea pink shrimps is an abundant penaeid species which inhabits the Gulf Izmit and they were collected seasonaly. In the laboratory, abdominal muscles and hepatopancreas were removed for determination of glycogen, free glucose, total lipid, triglyceride, total cholesterol levels and mineral content. Furthermore, K, Na, Ca, Fe, Mg levels have determined in abdominal muscle tissues of females and males. Our findings in Parapenaeus longirostris suggest that lipids and carbohydrates are main reserve of metabolic energy used during physiological activities in both males and female shrimps.

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