Two methods of artificial insemination and removal of copulatory plugs were used to investigate the role of the plug in the guinea pig. In addition, the effectiveness of the copulatory plug in blocking the passage of spermatozoa from the second mating was tested in albino females, where coat color was used as a genetic marker. Thirteen female guinea pigs that were either in proestrus, estrus, or metestrus, and inseminated with freshly collected copulatory plugs containing living spermatozoa, did not conceive. In a group of six females from which the copulatory plus was immediately removed, five conceived. Of nine estrous females artificially inseminated, five conceived. In five albino females, copulatory plugs from albino males completely blocked spermatozoa deposited by colored males, and 20 offspring, all albino were born. In a second group of four albino females where the plugs of albino males were removed prior to copulation with colored males, resulting litters were sired by either male or a combination of both males.

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Epithelial cells of the rat epididymis are of two major types, principal and holocrine. So called basal, apical, and clear cells represent different stages of the holocrine cell cycle in which it accumulates secretion products, dies, and is replaced. The two cell typss differ not only in their secretory behavior, but also in mitotic characteristics and staining properties. Condensed mitoses of holocrine cells occur in the basal epithelium, but larger mitotic figures of principal cells occur in their own apical regions. Holocrine cells are acid phosphatase positive only in their activated basal forms, but are strongly PAS and silver positive in all stages except when disintegrating. In principal cells, cnly the Golgi area is acid phosphatase and silver positive, and small scattered PAS gianules also appear in this region. While secretory functions of both cell types are under testicular hormone control, frequent mating releases holocrine cells from the e:pithelium into the lumen where they disintegrate. A shortened cycle in mated males occurs within 24 hours. Holocrine cells are also present in the rat vas deferens. Cells with similar staining reactions occur in ductuli efferentes and seminal vesicles of the rat, and in epididymides of hamsters and guinea pigs. Similar fixation methods and staining reactions applied to purified glycerylphosphorylcholine indicate that ho:locrine cells may accumulate and secrete this constituent of epididyma1 fluids.Recently Martan and Risley (in press) reported that frequent matings resulted in distinct alterations in epithelial cell structure in the epididymis of the rat. Marked increases in columnar cell heights, especially in sperm-free operated sides of mated hemicastrate:;, enabled the study of differences in staining reactions of epididymal cells and the recognition of relationships between so-called basal, apical, and clear cells. This report dealt mainly with principal cells and some of their staining properties. In the present paper all other epithelial cells are considered. Basal, apical, and clear cells are regarded as developmental si:ages of a holocrine type of secretory cell in the rat epididymis. This holocrine cell accumulates secretion within itself, dies, and is replaced by another cell.This concept reduces the epididymal epithelial cell population into only two major types of cells, and simplifies and clarifies some secretory funchons of the epididymal duct; it also suggests certain relations to spermatozoan maturation. MATERIALS AND METHODSTwenty-six male rats of Long-Evans and Wistar strains, bred and maintained in our colony, furnished the materials studied.One adult male hamster and one guinea pig were also used. Six experimental groups were prepared for study as follows:( 1 ) Hemicastrated adult males ( 4 ) ; ten days after the operation they were kept for ten successive nights with receptive females, and were killed on the tenth morning.(2) Castrated adult males (2); treated as above.(3) Ten normal young males were killed in pairs at 20, 30, 40, 5...

Single spermatozoa and spermatozoa in rouleaux were found throughout the genital tract of 21 female guinea pigs killed 15 minutes to 24 hours after copulation. Three females killed three to five minutes postcopulation had single spermatozoa and spermatozoa in rouleaux in the vagina, cervix, and uterus but not in the oviduct, The number of rouleaux and the number of spermatozoa in individual rouleaux decreased after copulation in all parts of the female genital tract with time while a corresponding increase in single spermatozoa was evident. The rate of rouleaux dissociation was faster in uteri than in oviducts. Only single spermatozoa were found near ova in the oviducts. The uterotubal junction appeared to act as a barrier to multitudes of spermatozoa passing from the uterus to the oviducts. However, some single spermatozoa and some rouleaux passed this barrier. Unusually large rouleaux were observed up to 12 hours after copulation in the pockets of the uterotubal junction. Single spermatozoa and few rouleaux of two spermatozoa in the uteri of females killed 8 to 24 hours postcopulation were phagocytised. No phagocytosis of spermatozoa was observed at any time in the oviduct.