360 SWINE PRACTICE 



GESTATION PERIOD 



The gestation period in the sow varies from 110 to 120 days. The' 

 first gestation period is usually about 112 days, and aged sows may 

 not farrow until the -120th day after conception. 



ANATOMY OP THE PEIIALE GENITAL ORGANS 



The ovaries are irregularly lobulated, due to the prominence of 

 the graafian vesicles. The uterus is supported by a large broad liga- 

 ment. The uterine horns are long and are the portion of the uterus 

 that contains the fetal pigs. The blood-vessels of the uterus, through 

 which the fetuses are supplied with nutrition, are irregularly ar- 

 ranged in tufts, particularly in the horns. The body of the uterus 

 is short and completes the communication between the uterine horns 

 and the vaginal canal. The vulva is relatively small and contains the 

 ducts or canals of Gartner. 



The mammary glands, ten or twelve in number, are arranged seri- 

 ally on either side of the median line. Each gland has a separate teat 

 which is pierced by openings. 



The fetal membranes are those structures between the fetus and the 

 uterine mucosa. They are three in number and from without inward 

 are: the chorion, allantois and amnion. Ea^h fetus is completely en- 

 veloped with separate membranes during the first part of the period 

 of gestation, although the chorion and parietal portion of the allan- 

 tois of each fetus overlap the same membranes of the adjacent fetus. 

 In the later period of gestation there is apparently a fusion of the 

 chorion and its attached parietal allantois membrane with the cor- 

 responding membranes of the adjacent fetuses and at the same time 

 there is a solution of the membrane in most eases within the fused 

 areas excepting the margin, and the allantois space thus becomes con- 

 tinuous and is common to all of the fetuses within the gravid Uteras. 



The chorion is the most external, is a closed sac, and assumes the 

 shape and contour of the horns of the uterus. This membrane is prin- 

 cipally concerned in the supply of nutrition to the fetus. 



The amnion, also a closed sac, is the innermost membrane and com- 

 pletely envelops the fetus. This membrane secretes and retains a 

 fluid, the amniotic fluid, which gradually increases in amount and 

 just prior to parturition is of sufficient volume that the fetus literally 



*The umbilical cord is the means of communication between the fetus and uterus. 

 It is composed of embryonal connective tissue, which supports the urachus, arteries and 



