OVULATION AND EGG TRANSPORT 



DEFINITION : A study of the process by which the egg is released from the ovary and is 

 carried to the uterus. 



PURPOSE : To become acquainted with the changes in the egg that occur between its hiberna- 

 tion environment in the ovary and its delivery into the chamber (the uterus) for ovi- 

 position, and to study the functions of the various parts of the reproductive tract of 

 the female in relation to the preparation of the egg for insemination. 



MATERIALS : 



Biological : Mature frogs, male and female (Eana pipiens). 



Technical : Dissecting instruments; hypodermic syringe and #l8 needle; wide-mouthed 



pipettes; finger bowls, Syracuse dishes, Petri dishes, stenders. Standard 

 (Holtfreter's) Solution. 



METHOD : 



Precautions : The ovulating female must be studied at the height of sexual activity, 

 before all of the eggs have reached the uteri. The opened body cavity should be 

 kept moist with Standard Solution. 



Control : No control is possible for this type of experiment for it is a matter of ob- 

 sei^ation of a normal process. 



Procedure : 



Induce ovulation in a female Eana pipiens in the usual maimer (see "Induced 

 Breeding") and keep the frog at a laboratory temperature of about 25° to 25° in a 

 email amount of water. Test in l6 to 2k hours for the presence of eggs in the uteri 

 and examine every 6 hours, or less, thereafter until eggs begin to appear. Within 

 2 to 5 hours after the appearance of the first eggs in the uteri, the following ob- 

 servations are to be made. 



Cut off the head of the frog and remove its appendages, leaving the torso. 

 Avoid unnecessary squeezing of the body. Lay the torso on a biologically clean cork 

 dissecting board or on paper towelling and open the abdomen from the pelvic girdle 

 to the xiphistemum, avoiding all parts of the genital tract. Cut away a large 

 piece of the ventral abdominal wall, including the peritoneum, and pin it down 

 (inverted, with peritoneiim uppermost) to Permoplast in concentrated Standard Solu- 

 tion in a Petri dish. Pin back the abdominal wall and remove the viscera so as to 

 expose the entire reproductive tract. With a pipette add about 5 to 10 cc. of 

 Standard Solution to the body cavity and suck out any blood clots. 



THE OVARY 



Eemove one ovary completely and place it in Standard Solution in a finger bowl 

 shielded from all heat. Examine with the naked eye and then under low power magnification. 

 Identify the following: 



a. Lobes of the ovary - how many are there? 



b. Movement of the ovarian lobes - how frequent; can movement be stimulated; is 



it the smooth or striated muscle type of movement? Do the lobes move simultane- 

 ously or separately? 



c. 'Efifi, follicles : Locate an egg emerging from its follicle. Is the emergence 

 slow or rapid; is it accompanied by a flow of fluid or blood; do all eggs emerge 

 simultaneously; do any eggs rupture into the cavity of the ovary; are the eggs 

 in £iny way distorted as they emerge from their follicles? 



(See papers by Rugh 1955= Jour. Exp. Zool. 71:l65.) 



-IIU- 



