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

¹ From the Department of Zoology, University College, Northwestern University, Chicago, Illinois

1. Two ovigerous folds, one on either side of the median sagittal septum of the ovary are described as bearing the germ cells.

2. Oöcytes normally occur in clusters at the surface of the ovigerous folds.

3. Follicular pores or delles not only facilitate access of the spermatozoa to the ovum but also provide a place for the escape of the fertilized egg.

4. The growing oöcyte is characterized largely by the absence of large masses of yolk and the presence of numerous oil droplets. During growth the nucleus changes from a typical germinal vesicle to a granular, eosinophylic body in which the chromatin exhibits only a weak affinity for stains.

5. The follicle of Neotoca changes during growth from a tenuous layer of scattered squamous cells to a thick, simple layer of columnar cells.

6. Fertilization, the completion of the meiotic divisions, and the escape of the egg are described as occurring simultaneously or in extremely rapid succession.

7. Normally evacuated follicles cannot be compared in any way to the mammalian corpus luteum.

8. In the atresia of the follicles the following phenomena are believed to occur: some fatty degeneration, some liquefaction or vacuolization of cells, some lymphocyte infiltration, some phagocytosis, and lastly, some absorption by the surrounding cells.

9. 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.