AN EXPERIMENTAL STUDY ON THE URINARY TRACT AND THE CLOACA IN THE FOWL; A HISTOLOGICAL STUDY

The Ist Report

Abstract

In the fowl, faeces and urine are kept together in a cloaca which is due to its physiological constitution, and the urinary tract remains sterile in spite of the contamitution of the uretero-cloacal orifice by faeces. The condition of the urinary tract after ureterosigmoidostomy in the mammals is entirely the same that of the cloaca of the fowl, but the upper urinary tract, unlike the cloaca, has always the tendency to get the ascending infection.
How is it that such a difference exists between the cloaca of the fowl and the sigmoid after ureterosigmoidostomy? The present study has been made in order to determine wether or no the urinary tract and the cloaca of the fowl have some special histological and functional protections against the ascending infection. In this first report. I am showing the result of the experiment with 23 fowls on the histological structure and arrangement of ureters, cloacas and uretero-cloacal orifices, and also the dynamic fuuction of the ureterocloacal orifices.
The result is summarized as follows:
(I) Histological view:
(a) Ureter: The mucosa is composed of the columnal type of epithelium, which contains a bit of mucus in it. Under this layer there is a lymphoid tissue. The muscularis is composed of three kinds of fibers, viz, outer thin interlacing, middle oblique and inner longitudinal. There is no communication between adventitia and surrounding tissues.
(b) Cloaca: The cloaca resembles very much the large intestine of the mammals, but its muscle layer is very strongly developed. It is divided into 3 chambers. The urodeum is the smallest one, and is the outlet for the urinary system.
(c) Uretero-cloacal enterance: At first the ureter is outside of the muscularis of the cloaca, then transpieces the muscularis (not cutting off the cloaeal musculature), and finally passes obliquely the mucosa. The muscle layer of the ureter and that of the cloaca are completely independent of the each other, The ureter opens, not directly into the cloaca, but into the mucosal duct that is the projection of the cloaca. The mucosal layer of the ureter becomes thick and we can see lymphoid tissues in it.
(2) Dynamic mechanisms of closing the ureteral orifices:
The ureteral orifice is completely closed as the result of its oblique course through the cloacal wall and also by the valve action of the mucosal duct. I. suppose that these mechanisms protect the urinary tract against the ascending infection.
(3) Physiological significance of the histological structure:
The columnal type of ureteral epithelium, its mucous secretion, and the existance of abundant lymphoid follicles and cysts in the lymphoid tissue, are also each, the specific protection against the bactrial infection.