In this work, the feasibility of separating and characterizing cell populations by steric field-flow fractionation (steric FFF) is demonstrated by application to fixed human and avian red cells, fresh blood from several species, and viable HeLa cells. The basis for this work is established by means of a discussion of the role of steric FFF in the broad family of field-flow fractionation techniques. The behavior of steric FFF is then characterized by application to standard polystyrene latex beads and to fixed red blood cells. Studies of these standards and of the other cells noted under various conditions of field strength and flow velocity are used to improve the separation conditions and approach optimization. It is shown that the fixed human and avian red cells can be separated in a time of less than 15 min. In addition, it is shown that HeLa cells maintain their viability after passage through the separation channel.

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Recent observations of social behavior and reproduction in wolves, coyotes, hunting dogs, mongooses, and lions suggest possible involvement of pheromones in the regulation of reproductive activity. Observed phenomena resemble the known pheromonal effects in mice such as suppression or synchronization of estrus, induction of maternal behavior, and interruption of pregnancy. Further studies are necessary to verify the supposed biological effects of carnivore pheromones and to determine their chemical nature.

Levels of volatile fatty acids (VFA) in vaginal secretions (VS) of cows were nearly independent of concentration changes of acids in the gastrointestinal tract, while levels in urine showed marked dependence. During three-week cycles, the VFA concentrations in VS increased shortly before heat and decreased to one third on days 19-22. Some cows showed an immediate increase after heat while in others the increase was slow and gradual. Moderately increased levels at midcycle were probably related to interovulatory follicle growth. Content of VFA in VS of pregnant cows was significantly above the level of the postestrus drop. Some pregnant cows in the first two thirds of gravidity had substantially higher levels of VFA than the other cows. Changes in VFA levels have a potential value for estrus detection and pregnancy diagnosis in cows. The gas chromatographic method used is too slow and tedious for practical application, but a reliable semiquantitative test for rapid proof of VFA or acetic acid in VS would be a very useful device for field use. It would have a substantial impact on the economy of cattle production by minimizing the loss of time due to delayed breeding.