THE REPRODUCTIVE CYCLE OF THE VIVIPAROUS TELEOST, NEOTOCA BILINEATA, A MEMBER OF THE FAMILY GOODEIDAE. IV. THE GERMINAL TISSUE

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Abstract
The study is based on observations made on 30 ovaries fixed during all stages of gestation. Two ovigerous folds on the lateral surface of the ovary are described as bearing the germ cells. Oocytes normally occur in clusters at the surface of the ovigerous folds. Follicular pores or delles facilitate access of the sperm to the ovum and also provide a place for the escape of the egg from the ovigerous folds. The growing oocyte is devoid of large masses of yolk but contains numerous oil droplets. During growth, the nucleus changes from a vesicular body to a granular, eosinophylic structure. The follicle of Neotoca changes during growth from scattered squamous cells to a thick layer of columnar epithelium. Fertilization is described as occurring while the egg still is within the follicle although fertilization, the completion of the meiotic divisions, and the escape of the egg must occur simultaneously or in very rapid succession. Normally evacuated follicles are not comparable in any way to the mammalian corpus luteum. In the atresia of the follicles, the following phenomena probably occur: fatty degeneration, vacuolization of cells, phagocytosis, and lastly, absorption by the surrounding cells. Some, if not most, of the germ cells of the adult gonad of the [female] are believed to arise from the epithelium of the ovigerous folds.