798 



SPERM, OVA, AND PREGNANCY 



be attributed largely to the use of new and 

 improved techniques for the collection and 

 study of living gametes and embryos. For 

 this reason, the subject to which this chap- 

 ter is devoted will be introduced with an 

 enumeration and description of some of the 

 methods which have contributed so much to 

 the work of the last two decades. Most im- 

 portant of these are the methods which have 

 been developed for recovering eggs and em- 

 bryos from the oviducts and uterus, and 

 they, therefore, will be described as a pre- 

 liminary to the discussion which follows. 



Methods 



A. METHODS FOR RECOVERING MAMMALIAN 

 EGGS AND EMBRYOS 



1. Collecting Ova jrom the Oviducts 



In animals such as the guinea pig, rat, 

 mouse, and hamster, in which the oviducts 

 are highly coiled, several procedures may be 

 followed for obtaining the tubal eggs. The 

 coils of oviduct can be trimmed from the 

 mesosalpinx with iridectomy scissors. By 

 stroking the length of the tube with a fine, 

 curved, blunt probe, the entire contents can 

 be expressed and the ova separated from the 

 debris. 



Another method is that of placing the 

 oviducts in a balanced salt solution and 



Fig. 14.1. Apparatus for washing ova from the 

 oviducts of mammals. 



mincing them into small pieces with a pair 

 of fine, pointed scissors, and then searching 

 for the ova. Both of the above methods are 

 wasteful of time and material, because the 

 ova may be damaged and the full number 

 frequently is not recovered. 



The best method for obtaining ova from 

 the coiled oviducts of the rat, mouse, 

 hamster, and guinea pig is to insert a fine 

 pipette filled with a suitable solution into 

 the lumen of the fimbriated end. The pipette 

 is held in place with fine watchmaker's for- 

 ceps. Gentle pressure is exerted on the fluid 

 in the pipette by a simple arrangement 

 whereby air pressure can be controlled in 

 the manner illustrated in Figure 14.1. If the 

 oviducts are removed and cut just above the 

 uterotubal junction, ova may be seen to 

 escape slowly from the cut end. By control- 

 ling the pressure, all of the ova can be kept 

 within a circumscribed area and any other 

 contents of the oviduct, such as spermato- 

 zoa, can be accurately counted or evaluated 

 (Rowlands, 1942; Simpson and Williams, 

 1948; Blandau and Odor, 1952; Noyes and 

 Dickmann, 1960; Dickmann and Noyes, 

 1960). 



2. Oollecting Free Ova jrom the Uterus 



Flushing of free ova from the uterus has 

 been performed in the monkey (Hartman, 

 1944) and cow (Rowson and Dowling, 1949; 

 Dracy and Petersen, 1951). In the monkey 

 the uterine lumen may be entered with a 

 hypodermic needle inserted into the uterus 

 through the abdominal wall. The contents 

 of the uterus are then flushed through a 

 funnel, the stem of which has been inserted 

 into the cervical lumen. Several segmenting 

 eggs were obtained by this procedure. The 

 disadvantages of this method are two : first, 

 a large quantity of fluid must be examined, 

 and, second, the presence of cellular debris 

 in the washings makes it difficult to locate 

 the single egg. 



In rodents the cornua may be removed 

 from the body and separated into their 

 right and left halves. Each cornu is then 

 flushed with physiologic saline by inserting 

 a fine hypodermic needle into the oviductal 

 end. During the flushing, the cornu should 

 be gently stretched so as to release ova that 

 may be trapped within the endometrial 

 folds. 



