抄録
Studies on morphogenesis of uterine horn, especially with uterine caruncle in Japanese Native Cattle were undertaken. Uteri from thirty-three fetuses ranging from 5cm to 72cm in Crown-Rump length were used in this study. Longitudinal sections of the horn as well as cross sections were studied microscopically beside macroscopical observations. Stainings employed were hematoxylin-eosin, van Gieson's and periodic acid-Schiff procedure. Histolgical measurements were made with an aid of ocular micrometer.
Prior to appearance of caruncle, a loose bulge of mucosa accompanied by protuberance of epithelium are recognized in uteri of fetuses ranging from 18cm to 28cm in C. R. length. The uterine caruncle first appears in a fetus of 32cm-33cm in C. R. length and thereafer it acquires a trapezoid form during the period up to the stage of 35cm in C. R. length. Afterwards, the caruncle still continues to enlarge exclusively but the qualitative differentiation is not so remarkable.
In an early stage, the caruncle is identified as a bulge consisted of mucosal tissue exclusively. In uteri of fetuses larger than 35cm in C. R. length, ring muscle layer also elevates slightly beneath the caruncle and some fibers branch off into caruncular stroma in accordance with the growth of the caruncle.
In mucosa of uteri earlier than the appearance of the caruncle, only capillary vessels are found. With start of the caruncular growth, small blood vessels begin to penetrate into the stromal tissue of the caruncle. Thereafter they increase progressively in caliber and distribution. Circular blood vessels of subcaruncular uterine wall are observed to be larger than those of intercaruncular wall.
Wandering leucocytes are found very frequently in uterine wall of bovine fetuses larger than 33cm-35cm in C. R. length. Leucocytes are observed to be more frequently in larger fetuses and in outer layers of the uterus. Leucocytes observed are eosinophils, neutrophils, monocytes and lymphocytes.
The intercaruncular uterine mucosa of fetuses larger than 45cm in C. R. length is divided in two layers according to the density of stromal cells and these layers respectively represent similar characters as those of adult. Meanwhile, interior of the caruncle is that of embryonal connective tissue.
