The Difficulties of Fundulus Embryos

Although its survival, or hardiness, in captivity has made Fundulus a desirable laboratory organism in some respects, it also presented a set of challenges for embryologists like Trinkaus. First, Fundulus’s spawning season in the waters of Cape Cod is short, occurring mainly in June and July, and it is a difficult organism to breed in a laboratory setting. Second, Fundulus have a very tough chorion, the protective membrane shell that envelops the egg. Consequently, dechorionation, the microsurgical intervention of removing this shell without damaging the embryo, is very challenging. In his memoirs, Trinkaus describes developing a microscopic technique using sharpened Swiss Dumont watchmaker forceps to overcome this challenge (Trinkaus 2003, 95). In fact, Trinkaus became so skilled at dechorionating Fundulus eggs that his colleagues dared him to do it after a long evening at the Cap’n Kidd, the local pub in Woods Hole (Trinkaus 2003, 133). Trinkaus accepted the challenge and successfully carried out the procedure, although he admitted that it required more time and concentration given his inebriated state. And, last, Fundulus eggs contain large lipid droplets that slowly move throughout the yolk, which can block an embryologist’s view of the embryo. These lipids help the eggs to sink to the bottom of the water in Fundulus’s natural environment and serve as nutrients for the developing embryo. Trinkaus claimed that the “droplets were placed there by a vengeful Old Testament God to bug the experimental embryologist” (Trinkaus 2003, 96). Despite his frustration, Trinkaus figured out a way to overcome this nuisance by sucking out the lipids with a fine suction pipette.