Studies on the rigidity of the cervix of sows

Macro-and microscopic observations were performed on the reproductive organs of fourteen slaughtered sows, especially on rigidity of the uterine cervix. We divided the normal sexual cycle of sows into six stages according to macroscopic findings of ovaries. Six stages are as follows. First stage; follicle (7-12 mm in diameter) stage. 2nd stage; ovulatory stage. 3rd stage; reddish body (functional corpus luteum or early regressing corpus luteum) stage. 4th stage; yellowish body (re-gressing corpus luteum) stage. 5th stage; white body or small follicle (less than 4 mm in diameter) stage. 6th stage; medium follicle (4-6 mm in diameter) stage. Out of fourteen sows included in this study, five were classified as 1st stage and three as 3rd stage, respectively.Out of the remaining six sows, three were pregnant and the other three had a cystic ovary. The cervices obtained from five sows in the first stage of cycle were rigid and those obtained from three sows in 3rd stage, three sows in pregnancy and the other three sows having a cystic ovary were flabby. In ovaries of latter nine sows, functional corpora lutea were found. Among the genital tract, the parts from that of a low hill to longitudinal prominences were rigid. On the contrary, a part of flat surface and vaginal vestibule were always flabby.In an uterus of the sow in the first stage, edema was clearly detected in the endometrium but it did not extend to the cervical mucosa. Meanwhile, edema was frequently detected in the cervical mu-cosa of pregnant sows. No correlation between rigidity of cervix and the condition of the cervical mucosa was recognized. The characteristic forms of the inner muscle layer, i.e., a honeycomb shape in a rigid cervix and a scattered cloud shape in a flabby cervix, respectively, were recognized. Histomorphological differences of the shape of inner circular muscle layes are considered to be re-lated with regard to the degree of rigidity.