In order to determine what part the level of oestrogen in the body might play in the passage of ova through the female reproductive tract, 1249 freshly ovulated ova from donor rabbits were transferred into the uterine tubes of seventy-four ovariectomized recipients, fifty-three of which had previously been treated for 5-18 days with small daily injections of oestradiol benzoate. From 10 to 78 hr after transfer, 41 % of the ova were recovered from the uterine tubes, 9% from the uterine horns, and 23% from the vaginae of the recipient animals. Twenty-seven % of the ova were lost. The rate of ovum transport varied widely between similarly treated animals, and between the right and left sides of the reproductive tract of the same animal. Larger proportions of ova were retained in the uterine tubes, and smaller proportions in the uterine horns as the oestrogen dose was increased.The great variability in the stage of cleavage and in the thickness of the mucin coat of ova recovered from the uterus and vagina suggested that the ova might be widely dispersed through the uterine tubes and that they probably pass out of the uterine tube at widely different periods of time. Evidence is presented that ovum transport in ovariectomized rabbits with or without oestrogen treatment is very irregular, that ova may be ejected from either end of the uterine tube at almost any time after transfer, and that ova are not normally retained in the uteri of such animals.Approx. 1 \ g=m\ g oestradiol benzoate administered daily for 5-10 days was necessary to maintain the uterine weight of ovariectomized rabbits at about the same level as that in intact oestrous rabbits, and also to reduce the variability in egg transport observed in control and ovariectomized animals.Failure of the mechanisms that normally result in the transport of spermatozoa and ova through the female genital tract may be an important cause of reproductive loss in laboratory and farm animals. Considerable discrepancies between the numbers of ova ovulated and the numbers implanted have been reported in a wide variety of species (for review see Brambell [1948]). The studies of Hertig, Rock & Adams [1956] suggest that the failure of transport of the gametes may be the commonest cause of idiopathic infertility in women.The remarkable ability of the female genital tract to transport spermatozoa rapidly, though in restricted numbers, to the fertilization site in the uterine tube, and sub¬ sequently to transport the ova in the opposite direction, has been the subject of much study. The major factors involved in these processes are the relative sizes of the spermatozoa and ova, the motility of the spermatozoa, the action of tubai cilia, the contractility of tubai and uterine muscle, the secretion of cervical mucus and of tubai

Colonic mucosal samples were obtained every 4 weeks for 13 months from 6 clinically normal dogs and from 47 dogs with a clinical diagnosis of chronic inflammatory bowel disease. All samples were graded on a scale of 0-5, based upon the quantity of lymphocytes and plasma cells in the lamina propria, epithelial changes, and the presence of ulcers and erosions. A grade of less than or equal to 2.0 was considered normal and was assigned to 77 of 78 samples from clinically normal dogs and 28 of 48 samples from dogs with diarrhea. A transient increase in cellularity was noted in 1 sample from 1 control dog. Nineteen dogs with clinical disease had obvious histologic abnormalities. The grading scheme described provides the pathologist with an objective criterion for the microscopic evaluation of colonic mucosal samples obtained by endoscopic techniques and offers clinicians a method of assessing the dog's progress and response to therapy.

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