26 SOUTHERN PORK PRODUCTION 



cell passes to the female organs and is attracted to the 

 female germ cells, with fertilization as the result. 



Female germ cell (ovum). — These cells originate in the 

 ovary in a manner somewhat similar to the way in which 

 the spermatozoa originate. The cell is very large. Each 

 of these cells, as a rule, unites with one spermatozoon to 

 develop into the embryo from which a pig comes. In 

 some instances a fertilized ovum may split and two pigs 

 may result from the same cell, but more often each pig 

 comes from a separate ovum after it has united with a 

 spermatozoon. This cell is not mobile, but it gravitates 

 from the ovary to the uterus by the oviduct or the 

 Fallopian tube. 



Fertilization of ovum. — The female cells travel toward 

 the uterus, and the sperm cell travels about in the uterus 

 and may go up the Fallopian tube to meet the female cell 

 to which it is attracted. When the two cells meet, the 

 male cell enters the female cell, leaving his tail behind, 

 with the result that the two nuclei of the germ cell 

 coalesce to start the process of cell division which results 

 in the embryo from which the pig comes. Since the 

 hereditary material of an animal is carried in its germ 

 plasm, the offspring partakes of the characters of both 

 parents. 



Pregnancy. — When the male germ cell unites with the 

 female cell the result is a pregnancy. The pregnancy 

 extends until parturition. When a sow becomes preg- 

 nant it is indicated by (1) cessation of periods of heat, 

 (2) change in disposition, (3) tendency to fatten, (4) en- 

 largement of the abdomen, (5) and in the later stages by 

 sinking of loins, congestion of udder and external 

 genitals. 



