106 OVULATION AND EGG TRANSPORT 



The body cavity eggs ol an ovulating female could be transplanted to the body cavity 

 of a non-ovulating female and there would be picked up by body cavity cilia and trans- 

 ferred to and through the oviducts to reach the uteri where they are fertilizable. This 

 can be done simply by making a small abdominal incision in a non- stimulated female, 

 under anesthesia, and transferring the eggs by pipette. The incision can be sewed 

 with silk thread, without particular aseptic precautions. 



4. That the female body cavity is extensively lined with ciliated epithelium can be fur- 

 ther demonstrated by excising a portion of the liver and placing it on a microscopic 

 slide in some Standard Solution. Using direct and reflected lighting and low power 

 magnification it will be possible to observe the surface and the edge of this piece of 

 liver for evidences of ciliary currents and cilia. As the surface becomes slightly 

 dried it will be possible to observe fields of cilia, rather unevenly distributed. A 

 thin strip of the edge of the liver placed under a coverslip and examined with trans- 

 mitted light under high power magnification will show the continuous action of mar- 

 ginal cilia. Similarly examine the liver of the male frog. The presence of cilia may 

 be considered as a secondary sexual character of female frogs. 



THE OVIDUCTS 



The oviducts of this ovulating female should be filled with eggs. Observe a single egg 

 through the walls of the oviduct as it is being propelled toward the uterus. The egg will 

 be seen to rotate (spirally) within the oviduct at the rate of about one complete turn in 14 

 seconds. Does the next egg in line rotate in the same direction? What is the cause of 

 rotation? 



Since the body cavity eggs cannot be fertilized and will not cleave, it is of interest to find 

 where this change in fertilizability occurs. Arrange finger bowls with concentrated sperm 

 suspension, made up of 2 testes per 10 cc. of Standard Solution, and label the bowls as 

 follows: 



a. Upper third of oviduct 



b. Middle third of oviduct 



c. Lower third of oviduct 



d. Uterus 



Tie a piece of cotton thread (or dental floss) around the uterus at its upper extremity, at 

 the point of junction with the oviduct. Similarly tie a thread around the lower limit of the 

 uterus after separating the two uteri. Then excise the entire oviduct and keep it moist 

 with Standard Solution. Cut the oviduct into thirds and slit each section open and shell 

 out the eggs (with the aid of forceps) into the appropriately marked finger bowl. To get a 

 sufficient number of eggs both oviducts may be used. Treat the fertilized oviducal eggs 

 in the normal manner and observe for: 



a. Percentage cleavage and normality of development. 



b. Amount and arrangement of the jelly on eggs from different levels of the oviduct. 



The eggs in the uterine sac are presumably normal and can be expelled into a normal 

 sperm suspension as control eggs for the above observations. These eggs are all in 

 metaphase of the second maturation division and are excellent material for physiological 

 experiments. 



The above observations will consume several hours of time but can all be made on a 

 single ovulating frog if the tissues are kept moist in appropriate Standard Solution and 

 are not allowed to become overheated. Spring Water may be used instead of Standard 

 Solution. 



