Studies on the reproduction of the dogfish

Abstract

In most groups of vertebrates, migration of ova from the ovary to the coelomic opening of the oviduct has been observed. This has been done by opening the abdomen of anaesthetized animals at the appropriate time. Thus, in the common fowl, Coste (1874) has found and Patterson (1910) confirmed that the infundibulum clasps the follicle before ovulation and that the pressure exerted is probably a causative factor in extrusion of the ovum. Though the process has never been observed in reptiles, the size of the ovum and proximity of the ovary to the oviducal funnel suggest that it is similar. Heape (1905) describes ovulation in the rabbit, stating that it normally occurs about 10 hr. after coition. Ovulation in the rabbit has been witnessed and described by Walton and Hammond (1928). Here, and in marsupial and placental mammals, the ovum is small and the ovary lies against the funnel, which is ciliated. It has been suggested by Corner (1921) that, in addition, peristaltic movements of the Fallopian tube may set up suction resulting in currents running into the infundibulum. There is little chance, in such cases, for an ovum to be lost in the coelom.