The epithelium of the oviduct of the pig-tailed monkey, Macaca nemestrina was studied 1) to determine whether quantitative changes in the number of ciliated, deciliated, reciliating and nonciliated cells occur during the menstrual cycle and under certain experimental conditions and 2) to describe the ultrastructure of the ciliated and ciliogenic cells. The mean percentage of ciliated cells decreased from 48.2 in the fimbriae and 48.3 in the ampullae in the postovulatory stage to 7.7 and 18.8, respectively in the late luteal phase; these changes are significant as determined by Duncan's multiple range test. In the early follicular phase 3.9% of the cells in the fimbriae and 11.2% in the ampullae are ciliated, and the number of ciliogenic (deciliated and reciliating) cells is the highest of any time in the cycle in both the fimbrial (6.3%) and ampullar (8.4%) epithelium. In contrast, although the percentage of ciliated cells in the isthmus varies from 44.4 in the preovulatory phase to 34.3 in the early follicular phase, the differences between the various times in the cycle are not significant. However, in the late luteal phase, the values for the fimbriae and ampullae are significantly different from that of the isthmi. Ciliated cells constitute less than 1% of both the fimbrial and ampullar epithelium 2 3/4 years after ovariectomy, but 16.7 in the isthmic tissue. In ovariectomized monkeys treated for 7 or 12 days with estradiol benzoate reciliation occurs, but to a significantly lesser extent in the fimbriae and ampullae than in the pre- or postovulatory animals; the degree of reciliation in the isthmus is not different from the values noted during the cycle. The ultrastructure of ciliated, deciliated and reciliating cells is described. Of much interest is the finding of cytoplasmic protrusions containing variable numbers of ciliary axonemal complexes. It is postulated that such internalization of ciliary micotubules may represent one way in which deciliation may be accomplished.

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The secretory cells of the oviductal epithelium in the pig-tailed monkey, Macaca nemestrina, have been studied by light and electron microscopy. Changes during the menstrual cycle and after ovariectomy, with and without subsequent estrogen treatment, have been documented. During the early follicular phase the epithelium is recovering from deciliation and secretory cell atrophy that occur in the late luteal phase. A few fimbrial and a moderate number of ampullar and isthmic cells contain a few electron-dense, homogeneous secretory granules in their apical cytoplasm. During the late preovulatory and early post-ovulatory periods, secretory cell structure varies considerably. Fimbrial cells typically display apical protrusions that contain no or a few small, mainly homogeneous, secretory granules. The cytoplasm is crowded with elements of the Golgi complex, with granular endoplasmic reticulum profiles often intimately associated with mitochondria, and with variable numbers of polysomes and glycogen granules. In ampullar and isthmic cells secretory granules are more abundant than in fimbrial cells, and electron-lucent vacuoles appear. The granules are of two types: 1) those having an electron-dense, homogeneous matrix, and 2) those possessing lamellar structures within moderately dense matrices. The lamellae of the second type course in parallel arrays separated by a distance of approximately 15.5 nm and exhibit a periodicity of approximately 11.3 nm. Possible transitional stages between the lamellar granules and the vacuoles containing lamellar fragments are observed. Secretion occurs by exocytosis. During the late luteal phase no fimbrial cells have secretory granules. In the ampulla many of the cells have poor development of the organelles involved in secretory activity and have few or no secretory granules. In others, a moderate number of secretory granules are present; in one animal, exocytosis is observed. In the untreated ovariectomized animal no secretory granules occur, and the organelle content is much less than in the cycling and the estrogen-treated monkeys. In ovariectomized, estradiol-treated monkeys, some areas of all three oviductal segments are well stimulated whereas others display little or no secretory activity.

Many of the cilia in the oviducts of rhesus monkeys are formed in the follicular phase of the menstrual cycle, and lost in the subsequent luteal phase (Brenner, '69a). This striking phenomenon has rarely been observed in other species, and its occurrence in human oviducts is a point of dispute. This study was designed to determine whether cyclic shedding and renewal of oviductal cilia occur in a primate species other than the rhesus monkey and to reveal the surface characteristics of the oviductal mucosa in a subhuman primate. Oviducts were removed from Macaca nemestrina females a t three specific times during the menstrual cycle and examined by scanning electron microscopy. The fimbriae appeared to be extensively ciliated a t midcycle but only sparsely ciliated in the early follicular and late luteal phases. Early in the cycle, large numbers of cells were seen in the process of ciliogenesis, but in the late luteal phase there were signs of ciliary degeneration and shedding. The ampullar epithelium showed similar though less dramatic changes, and the isthmus little change. Long-term ovariectomy caused almost complete deciliation of the fimbrial and ampullar epithelium, but treatment of ovariectomized animals with estrogen for only a few days restored the epithelium to normal. Despite the high degree of variability in the mucosa, it was clear that the oviducts of M. nemestrina, like those of the rhesus monkey, undergo cyclic ciliogenesis and deciliation. The surface features of the oviductal lining in M. nemestrina are described here for the first time.One of the most remarkable discoveries about the mammalian oviduct in recent years has been the finding that, in the rhesus monkey, oviductal cilia are regularly produced and shed with each menstrual cycle (Brenner, '67, '69a,b). Large numbers of cilia are formed during the early part of the follicular phase, creating a richly ciliated epithelium by midcycle when ovulation occurs. During the late luteal phase, extensive atrophy and deciliation occur. These changes are most marked a t the fimbriated end. In the ampulla and isthmus the epithelial cells undergo cyclic hypertrophy and atrophy, but ciliogenesis and deciliation occur only rarely.Changes of this nature are obviously important to document in view of fimbrial function. In many mammals, including the monkey, it is the cilia of the fimbriae that are primarily responsible for the pickup and first phase of transport of ova (Blandau, '73; Odor and Blandau, '73). The importance of a richly ciliated epithelium a t midcycle is obvious, but the functional significance, if any, of cyclic ciliogenesis and deciliation is not yet clear.Apart from a brief mention of similar cyclic changes in the oviducts of cynomolgus monkeys, M. fascicularis (Brenner et al., '73), there have been no reports on the extent to which this phenomenon occurs among other subhuman primates. Yet this would seem to be an important area for investigation, since studies on human oviducts have already produced conflicting data on this issue....

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