Sex-Limitation of Cilia in Body Cavity of the Frog (R. pipiens)

Abstract

The occurrence of ciliary systems in the peritoneal lining of the body cavity of the frog has long been known (Gray 1 ) but, so far as the writer is aware, the fact that they are sex-limited and appear only in the female has hitherto been unrecognized. However a comparative study of the peritoneal lining of the body cavities of 20 female and 20 male frogs (R. pipiens) has shown that such ciliation occurs only in the female and may be regarded as being strictly sex-limited. This study was made on frogs taken during the breeding season (April-May) at which time the ovaries of the females were greatly enlarged. Strips of the thin peritoneal lining were removed and temporarily mounted in frog Ringer for examination. The cilia show up clearly when illuminated by unfiltered light and with the diaphragm of the microscope almost completely closed. An 8 mm. objective combined with a No. 18 eyepiece proved to be the most adequate lens combination for this type of work. In the female frog ciliary systems are present throughout the ventral and lateral areas of the peritoneum, extending the entire length of the body cavity and including the pericardial region; they are particularly numerous in the peritoneal tissue immediately adjacent to the ventral abdominal vein. The ciliary beat is in an anterior direction (towards the ostia tubae). By this means the movement of the ova towards the ostia is facilitated. Since frogs kept in captivity do not ovulate, the actual transportation of the ova was not observed. In a similar study on 20 male frogs it was found that cilia were entirely absent from all parts of the peritoneal lining.

That the ciliation found in the peritoneal lining of the female frog might be under hormonal control seemed likely. Previously Wolf 2 showed that castration atrophy of the oviducts of the female R. pipiens could be prevented by daily injections (2 RU) of mammalian follicular hormone. In order to ascertain the possible relation of peritoneal ciliation to the follicular hormone a series of mature, intact male frogs were injected with 5 RU of theelin∗ intraperitoneally daily for varying intervals. Frog T1, examined after 9 daily injections, showed no cilia in the peritoneal lining.