REPRODUCTR'E ENDOCRINOLOGY IN BIRDS 



1123 



which is hctUT dcvclopt'd than that in the 

 magnum. The epithelium consists of ciliated 

 and nonciliated cells and of goblet cells 

 with little or no affinity for mucin-staining 

 dyes (Richardson, 1935). The transition 

 from isthmus to shell gland is gradual. The 

 area is characterized histologically by the 

 presence of special glandular cells which 

 show a distinct vacuolization, a pale cyto- 

 plasm, and a scarcity of granules. In this 

 area tubular glands of the isthmus and of 

 the shell gland api:)arently do not mix 

 (Richardson, 1935). The change in epi- 

 thelium is gradual. 



4. The shell gland is about 8 cm. long and 

 has a larger diameter than the isthmus or 

 magnum. The longitudinal muscle layer is 

 well developed. The mucosal folds have 

 diagonal and transverse secondary folds. 

 The tubular gland cells of the shell gland are 

 smaller than those of the isthmus. The epi- 

 thelium consists of a single layer of cells 

 with apical and basal nuclei (Richardson, 

 1935) and of some goblet cells which lack 

 affinity for mucin stains. In the shell gland 

 the egg receives the thin albumen in 4 

 to 8 hours. The shell is deposited around the 

 membranes, and indications are that shell 

 formation continues as long as the egg stays 

 in the shell gland which is about 20 hours on 

 the average (Warren and Scott, 1935) . 



5. A sphincter separates the shell gland 

 from the vagina. In birds which are not 

 secreting sufficient estrogen to have caused 

 its breakdown (Greenwood, 1935; Kar, 

 1947a) the occluding plate which is proba- 

 bly homologous with the mammalian hy- 

 men can also be found. The vagina is 

 characterized by its highly developed, circu- 

 lar muscle layer and a mucosa with flat, 

 longitudinal folds. The vaginal epithelium 

 consists of nonciliated and ciliated cells, 

 and of tall goblet cells. The latter stain 

 with the same dyes as do the goblet cells 

 of the magnum. The principal function of 

 the vagina is its j)articipation in the ex- 

 Dulsion of the egg. 



The infundibulum of the oviduct of the 

 fowl is innervated by nerve fibers originat- 

 ing in the ovarian plexus; these nerves 

 transverse the dorsal ligament before reach- 

 ing the oviduct. The more posterior parts of 

 the oviduct receive nerve fibers from various 



autonomic jilexuses along the abdominal 

 aorta (Alauger, 1941). 



The pigeon's oviduct receives blood from 

 the genital artery and from the pelvic 

 artery, a branch of the iliac artery (Bha- 

 duri, Biswas and Das, 1957). The anterior 

 portion of the oviduct of the fowl receives 

 blood from a branch of the renal artery. 

 The magnum is supplied by a branch of the 

 left sciatic artery and the shell gland by a 

 branch of the arteria pundendal communes. 

 The blood from the oviduct drains into the 

 common iliac vein and from this into the 

 vena cava. 



In the adult bird, the ovarian hormones 

 mainly control structural changes and the 

 secretory activity of the oviduct. The ad- 

 ministration of estrogen to immature pul- 

 lets dramatically increases the size of the 

 oviduct (Juhn and Gustavson, 1930; Kar, 

 1947a; Brant and Nalbandov, 1956) and of 

 the dorsal and ventral ligaments (Kar, 

 1947a). It also initiates the breakdown of 

 the occluding plate (Kar, 1947b). Although 

 1.00 mg. of estradiol benzoate per day may 

 induce a 20-fold increase in oviduct size, 

 it fails to induce development of the tubu- 

 lar glands of the oviduct or to induce al- 

 bumen secretion by the magnum. The de- 

 velopment of the tubular glands and the 

 secretion of albumen can be induced by 

 a combination of estrogen and either pro- 

 gesterone or androgen, whereas neither of 

 these hormones alone produces this effect 

 (Brant and Nalbandov, 1956). Estrogen ad- 

 ministration induces riboflavin secretion in 

 the magnum, but the secretion increases 

 18 to 35 per cent if the estrogen is given 

 in combination with progesterone or testos- 

 terone or with both (Bolton, 1953). The 

 secretion of avidin by the oviduct is also 

 a synergistic response to combinations of 

 estrogen and progesterone, and to estrogen- 

 desoxycorticosterone acetate (DOCA) com- 

 l)inations. However, DOCA, progesterone, 

 or testosterone when given alone can in- 

 duce avidin secretion by the oviduct (Hertz, 

 Fraps and Sebrell, 1943, 1944). A curious 

 phenomenon is that estrogen and progester- 

 one act synergistically to cause avidin secre- 

 tion, but, at the same time, progesterone 

 inhibits the estrogen-induced increase in 

 oviduct size (Hertz, Dhvse and Tullner, 



