Pregnant females were less frequent in the South African sample (2.9% vs. 14.9%), and there were no young calves (≤2 yr), but 13 in the Japanese sample (excluding three animals 148–196 cm in length for which there were no ages). The combined frequencies of pregnant females and young calves differed significantly between the two regions

(Chi square with Yates correction = 8.07, P = 0.0045). Excluding pregnant females, however, Birinapant the proportions of lactating, ovulating (including simultaneously lactating and ovulating), and resting females were similar in both populations (Chi-square with Yates correction = 0.094, P = 0.9541). Whales in the two samples reached similar maximum ages, 58.5 and 57.5 yr in 20 and 45 males and 63.5 and 62.5 yr in 38 and 83 females from South Africa and Japan, respectively. In order to increase sample size, data from South African and Japanese females were combined (n = 120, of which 24 were immature) for most of this section. Only where there were obvious differences have the analyses been separated by population.

The number of macroscopically visible Fer-1 solubility dmso Graafian follicles in mature females varied greatly between individuals, with 42.1% having none. Although the proportion of animals with visible follicles was higher in younger (<39 yr old) than in older females (19/53 compared to 16/30), the difference was not statistically significant (Chi-square with Yates correction = 1.74, P = 0.1871). The diameter of the largest Graafian follicle ranged from 1 to 45 mm. Most (87.5%) of the follicles 10 mm or more in diameter were found in resting or ovulating females, while 88.9% of the largest follicles in immature, 75% in pregnant, and 90% in lactating females (that were not simultaneously pregnant) were less than 10 mm. Follicles 30 mm or more in diameter were only found in resting females, and although several (57%) of these were atretic, it seems likely that 30 mm was close to the diameter that the follicle attains at ovulation. A corpus luteum (CL) was found in 29 false killer

whales, 10 of which also contained a fetus, indicating that these were corpora lutea of pregnancy (CLPs). A female from Japan with a CL measuring 38.3 mm was classified as pregnant although no fetal length was recorded, MCE公司 possibly because the fetus was aborted or lost and endometrial histology or the presence of a fragment of placenta or umbilical cord indicated pregnancy (Kasuya and Tai 1993), while no data on CL size were available for another pregnant female as only one ovary was collected. An accessory CL 11.6 mm in diameter was found in a whale from Japan carrying a fetus 138 cm in length and with a main CL of 100.9 mm. No fetus was found in the uterus of the remaining 20 females, so the CLs of these females were assumed to be corpora lutea of ovulation (CLOs). No data were available for the diameters of one CLP and two CLOs. The remaining 10 CLPs (excluding the accessory corpus luteum) ranged in diameter from 38.3 mm to 100.