Infundibulum As the 'Trichter' and the Caudal Half As the 'Tube'
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Arch. histol. jap. Vol. 23, n. 5 (July 1963). P. 447-459. Dept. of Anim. Husb., Fac. of Fish. and Anim. Husb., Hiroshima Univ., Fukuyama, Japan. Histological and Histochemical Studies on the Oviduct of the Domestic Fowl with Special Reference to the Region of Uterovaginal Juncture. 鶏 の 卵 管, と く に 子 宮 と 腟 の 移 行 部 の 組 織 学 的 お よ び 組 織 化 学 的 研 究. Shunsaku FUJII 藤 井 俊 策. (Received May 30, 1963.) The histological structure of the oviduct of the domestic fowl has almost com- pletely been investigated by many workers, including SURFACE (1912), GIERSBERG (1921, 1922), FROBOSE (1928), BRADLEY (1928), and RICHARDSON (1935). SURFACE studied mainly the histological structure of the oviduct itself. RICHARD- SON observed in detail the function and histological s structure of the gland of the ovi- duct. At present, the oviduct is generally divided into five portions: the infundi- bulum or funnel, the magnum or albumen secreting portion, the isthmus, the uterus or shell-gland region, and the vagina. Each portion has its particular structure and physiological function for egg production. In addition, some workers have identified another portion as the region of juncture, where one type of mucosa intermingles with another type. For instance, GIERSBERG (1922) distinguished the cranial half of the infundibulum as the 'Trichter'and the caudal half as the 'Tube'. RICHARDSON, (1935)also subdivided the infundibulum into 'funnel'without glandsand the 'chalazi- ferous region'with glands, and insertedthe 'isthmo-uterineregion' between the isthmus and the uterus. In spite of such large number of histological observations as these, little has been reported on the histochemistry of the oviduct. In the course of histological and histochemical studies of the fowl oviduct, the author found the existence of characteristic mucous zones both at the caudal end of the uterus and the cranial end of the vagina. Each zone had definite histological and histo- chemical characteristics which distinguished it from its adjacent portion. The present paper deals mainly with morphological findings of the region of uterovaginal juncture. I. Materials and Methods. The oviducts collected from adult White Leghorn hens just after decapitation were used. The structure of the oviduct changes largely in accordance with the state of laying. Therefore, the oviducts used had been removed from nonlaying and laying hens in varying states of laying; that is, before ovulating, after laying, and stages where eggs were at different levels of the oviduct. They were classified according to the purpose of investigation and subjected to some suitable methods. For observation of general histological structure, they were fixed in BOUIN's and ZENKER's solution and made to paraffin sections 5-10μ thick, which were stained with hematoxylin 447 448 S. FUJII: and eosin and by HEIDENHAIN's azan and iron-hematoxylin methods. For demonst- ration of polysaccharide and mucopolysaccharide, they were fixed in CARNOY's solu- tion and 95% alcohol and stained by the periodic acid-SHIFF (PAS), LISON's alcian blue, and BEST's mucicarmine and mucihematein methods. For demonstration of the activities of alkaline and acid phosphatases, material was immersed in acetone, sectioned, and treated by GOMORI's calcium phosphate method and lead phosphate method, respectively. Some material was fixed in BAKER's calcium formalin and sectioned with a freezing microtome at a thickness of 15-20μ The sections were stained by the following techniques: for fat substances, BAKER's sudan black B and GIACCIO's sudan III stain, for phospholipids BAKER's acid hematein, MENSHIK's Nile blue and CIACCIO's sudan stain, for cholesterin and its ester SHULTZ's test, OKAMOTO's method and FEINGIN's digitonin method. In addition, the polarized- light method was employed for demonstration of cholesterin. II. Results. A. Macroscopical Observation. Macroscopically, the uterus is a somewhat flattened, elongated sac with trans- verse bands. The vagina is a narrow muscular tube, extending from the caudal end of the uterus to the cloaca. The boundary between the uterus and the vagina is indicated by the presence of a sphincter muscle. In more detail, the enlarged body of the uterus is constricted gradually in funnel shape as it approaches the narrow vaginal orifice, where the uterus ends abruptly. Caudal to the orifice, the vagina at first curves a little dorso-cranially, forming the first flexure. Then it ascends along the dorsal wall of the uterus for a short distance, about 1cm, enclosing the outer, longitudinal muscle of the uterus. It again turns suddenly backwards by forming the second flexure, after which it becomes smaller in caliber towards the cloaca, convoluting slightly in its course (Fig. 1). The inner surface of the uterus is thrown into a number of leaf-like folds of mucous membrane showing a faint rose pink color. On the other hand, that of the vagina is white in color and forms low, regular longitudinal folds. In the uterovaginal junc- ture, the transition of the mucous membrane is grad- ual, so that no clear demarcation is noticed, except a vague constriction around the vaginal orifice. Fig. 1. Outside appearance of the Careful observation of the terminal portion of the uterine and vaginal regions of the uterus indicates, however, that a narrow, ring- oviduct in a laying hen. Abbrevia- shaped zone, about 0.5-1cm wide, around the tion: Ub uterus proper, RU recessus vaginal orifice differs distinctly from the main por- uteri, Vg vaginal glanid region, Vp vagina proper. About 1/2. tion of the uterus in the color and shaps of the folds of mucous membrane. In this zone, the mucoss presents a characteristic grayish-white color, forming low, somewhat regularly ar- Histological and Histochemical Studies on the Oviduct etc. 449 ranged, longitudinal folds. These folds represent exactly an intermediate type between the uterine and the vaginal mucosal folds. This zone can be recognized by a naked eye, especially by the color of its mucosa, but the shade of its mucosa varies according to the activity of the oviduct. In general, this part of the uterus appears grayish- white in nonlaying hens, as well as in laying hens containing no egg in the uterus. Therefore, it is very characteristic of these hens. In hens which have just expelled eggs, this zone appears faint pink, with its regular color faded. Therefore, it is not so distinctly differentiated as before. The change in mucosal color suggests that some structural changes have occurred in the epithelium during the formation of egg-shell or expulsion of the egg. Accordingly, the caudal end of the uterus has not only these macroscopical features, but also such definite microscopical ones as mentioned below. So the author calls this portion as the recessus uteri, distinguishing it from the main portion of the uterus (hereinafter referred to as the uterus proper). Fig. 2. Inside appearance of the region of uterovaginal juncture. For abbreviations, see Fig. 1. Fig. 3. The mucosa of the uterus proper in a laying hen. Note luxuriant uterine glands. Hematoxylin and eosin (HE) staining. ×190. The beginning of the vagina, about 1cm long, between the first and the second flexure as mentioned above, is much larger in outside and inside diameter than the remainder of the vagina (hereinafter referred to as the vagina proper). The mucosal folds of the inner wall are lower and wider in the former than the latter. In addition, this part of the vagina is characterized histologically by the presence of many large tubular glands in the lamina propria which are to be mentioned below. So it is called the vaginal gland region, distinguishable from the vagina proper (Fig. 2). B. Histological Observation. As is generally known. the uterine mucosa is thrown into numerous folds with 450 S. PUJII: a few secondary ridges, which are lined by a pseudostratified epithelium composed of two kinds of cells, ciliated columnar and goblet cells. Situated in the lower position, goblet cells are extremely slender and scattered among tall ciliated cells located in the upper position. They are slightly positive to mucin stains in the PAS method, but are not stained with such dyes as alcian blue, mucicarmine, and mucihematein. The lamina propria is vascular and packed densely with highly branched tubular glands, known as the uterine glands. The glands are of large cuboidal cells with centrally located small, round nuclei (Fig. 3). Toward the caudal end of the uterus, the uterine glands decrease in number and gradually changes into small, simple tubular glands. Each gland has a narrow lumen Fig. 4. The mucosa of the recessus uteri in a laying hen. Note small tubular glands scattered in loosely arranged connective tissue. HE staining. ×190. Fig. 6. Fig. 6. The high-power magnification of Fig. 5. HE staining. ×400. Fig. 5. The mucosa of the juncture of the recessus uteri and the vaginal gland region. Note small glands mingling with large ones. HE staining. ×190. Fig. 5. Histological and Histochemical Studies on the Oviduct etc. 451 surrounded by a few low cuboidal cells. Although it seems to be different from the uterine gland, the cytoplasm of its glandular cells contains fine acidophilic granules characteristic of the uterine glands. In the recessus uteri continuous to the previous region, however, the surface of the fold is comparatively irregular, owing to an increase in secondary ridges. The lining epithelium has still essentially the same composition, although its goblet cells become smaller in number and larger in size than before and stainable with all the mucin stains employed before. It should be noted that the lamina propria of this region is composed of avascular loose connective tissue and has a few small glands scattered (Figs.