MANIPULATION OF EGGS 105 



Recovery of eggs from the guinea-pig Fallopian tube may be 

 troublesome owing to the large amount of fat that often surrounds 

 the tube; both flushing and manipulative techniques, however, have 

 been successfully employed. 



Eggs have been obtained by several investigators from the 

 Fallopian tubes of living animals (domestic animals, rabbit and man) 

 under anaesthesia (Appendix No. i; also Krassovskaja, 1934, from 

 the rabbit). This can be done by placing a clamp near the tubal end 

 of the uterus and injecting fluid into the isolated part of the uterine 

 lumen; the fluid flows along the Fallopian tube, carrying the eggs 

 with it, and can be collected as it escapes from the abdominal ostium. 

 When resistance is offered by the utero-tubal junction, as in the 

 rabbit, the fluid may be injected instead into the ampulla, by means 

 of a syringe inserted into the infundibulum; an opening is made in 

 the tubal end of the uterus and a short length of glass tubing inserted 

 into the isthmus through which the flushing solution runs (see Avis 

 and Sawin, 195 1). 



Recovery of cleaving eggs and blastocysts from the uterus is also 

 effected by flushing, though manipulation can be used with the 

 smaller rodent uteri. To extract large blastocysts without damage, it 

 may be necessary to make a large incision in the uterine wall, and 

 ungulate blastocysts are generally obtained in this way. Neverthe- 

 less, early bovine blastocysts have been removed from the living 

 animal without operative interference — this was done with the aid 

 of a special flushing tube or catheter which had separate lumina, one 

 for admitting the fluid to the uterine cavity and the other for 

 draining off fluid together with the suspended eggs (Rowson and 

 Dowling, 1949; Dracy and Petersen, 1951; Donker, 1955). 



For detailed study, eggs are taken up with a little of the surround- 

 ing medium into a finely-drawn Pasteur pipette and transferred to 

 a microscope slide. The capillary of the pipette should be about 

 2" to 3" long with an internal diameter a little larger than that of 

 the oocyte, namely of the order of 0-2 to 0-4 mm — it has been found 

 that fluid movements are most easily controlled with pipettes of 

 these dimensions. The egg should not be drawn more than half an 

 inch or so into the capillary, and certainly not into the wider portion 

 of the pipette, because there is then a risk that it will be left behind 

 in the pipette when the fluid is expelled. The same pipettes can be 

 used for transferring larger objects, such as an entire granulosa-cell 

 mass, by drawing the mass onto the tip of the pipette and holding 



H 



