RECENT FINDINGS IN THE INHIBITION OF AVIAN OVA SUSTENTATION 
Pedro F. Consuesra 
1. Structure of the oviduct and its function. 
The oviduct is a tube having many loops through which 
the yolk and germ pass for fertilization and the addition of the 
white and surrounding membranes. The tube extends from the 
base of the ovary to the cloaca. The oviduct, which is 2 feet 
long, varies in structure throughout in length in accord with 
its various functions, the different portions of this duct bee 
oe specialized for the secretion of the different parts of 
@ Cgg. 
The oviduct consists of the following five major 
parts: teethe infundibulum or funnel which picks up the yolk 
after release from the ovary, 2=--the magnum or albumen-secreting 
portion, 3--the narrow isthmus where the shell membranes are 
formed, 4--the pouch-like uterus in which additions to the white 
are made and the shell is deposited. If the shell is white, 
the egg is finished after shell deposition, except for the 
cuticle which is formed just prior to expulsion. In breeds 
that naturally lay colored eggs, the pigments are laid down in 
the shell gland. 5-=the vagina which leads from the uterus to 
the cloaca from which the egg is expelled. 
There is no sharp line of demarcation between most 
of these regions; the magnum comprises over 50 per cent and the 
isthmus and uterus about 15 per cent. | 
Warren and Scott (1935) obtained fairly accurate tim- 
ing of the passage of the egg through the oviduct. The calcu- 
lated time schedule was 18 minutes in the infundibulum, close to 
3 hours in the magnum, over an hour in the isthmus and between 
20 and 21 hours in the uterus and vagina. 
The development of the oviduct and its preparation 
to receive the mature ovum are directly controlled by the 
hormones of the ovary. (Herrick, 1944). As the time of ovula- 
tion approaches the individual gland cells and glandular folds 
enlarge, the ducts and cells become filled with secretory prod- 
ucts. Most of the proteins that contribute to the albumen are 
formed and accumulated at a fairly regular rate in the tubular 
glands of the anterior portion of the oviduct during the interval 
between successive eggs (Conrad and Scott, 1942). 
3. Factors affecting the structure of the oviduct. 
Finne and Vike (1951) described an hereditary atresia 
of the oviduct in a flock of young White Leghorn chickens in 
Norway. The females were apparently of normal development but 
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