Sterile Eggs Research Articles

Utilization of Sperm by the Female Drosophila Melanogaster

The number of sperms transferred by a 4- to 5-day-old wild-type male of D. melanogaster in a single copulation has been found by actual count to approach 4,000. In successive copulations the number rapidly decreases, until after a few matings no sperm is transferred. By the next day, however, additional sperm may be available for transfer. The amount of sperm transferred in a single copulation is only sufficient to guarantee ferilization of all eggs laid during the first few days by the average female. On subsequent days the percentage of sterile eggs increases, so that toward the end of the egg-laying period practically all eggs deposited are unfertilized. A measure was made of the ability of sperms of three types of males, namely, wild-type, Curly/Glazed and plexus brown speck, when used in all possible mating sequences, to take precedence in fertilizing the eggs of plexus brown speck females. The Curly and Glazed off-spring from these crosses were slightly more frequent than the wild-type; the plexus brown speck represented only about one sixth of the total progeny. Similar proportions were found among the offspring of plexus brown speck females, which were permitted to lay their eggs in the same bottle, after each had mated with only one of the types of males available. Such similarity suggests that the differences in frequency of different classes of offspring following polyandry are referable to differential viability of the different types of embryos and larvae, and not to differences in vigor or mortality of the various types of sperms leading to selective fertilization.

PRESERVATION OF EGGS. I.: TREATMENTS FOR MAINTAINING QUALITY IN SHELL EGGS AT ORDINARY TEMPERATURES

Cultural studies demonstrated the fungicidal value of urea and dimethylol urea and the effectiveness of the vapours of certain volatile solids as mould growth inhibitors. A method for preparing sterile artificial eggs for mould studies was developed.Investigations on 21 treatments for preserving eggs at high temperatures indicated that the best results would be obtained by the following procedure: conditioning with carbon dioxide to lower the pH, treating shell surfaces with a disinfectant to reduce contamination followed by effective sealing, preferably with a substance having properties that would prevent both growth and entrance of contaminants during subsequent storage. Dimethylol urea was the most effective growth inhibitor for micro-organisms and vaseline proved to be the best sealing agent. Satisfactory results were obtained by dipping eggs in polyvinyl alcohol treated with dimethylol urea and by packing oil dipped eggs in moisture resistant bags.

Experiments on the Injection of Pituitary Body (Anterior Lobe) Extracts to Axolotls

Experiments on the Injection of Pituitary Body (Anterior Lobe) Extracts to Axolotls

The relation of the Zona pellucida to the formation of the fertilization membrane in the egg of the sea-urchin (Strongylocentrotus purpuratus)

1) The Zona radiata of the immature egg becomes the Zona pellucida of the maturated one. 2) Spermatozoa are attracted by the unmaturated eggs in the same manner that they are attracted by the maturated ones. 3) Several spermatozoa may succeed in entering the unmaturated egg while under normal conditions only one spermatozoon is able to enter the maturated one. 4) Females vary in the percentage of fertile and sterile eggs found in the ovaries. 5) Sterile eggs do not attract the spermatozoa. 6) Sterility and absence of Zona pellucida are accompanying conditions. 7) Preservation of the Zona pellucida is closely associated with the preservation of the fertility of the egg. 8) The Zona pellucida furnishes the attraction stimulus for the spermatozoa. 9) After the Zonae are detached from the eggs the latter have no attraction for the spermatozoa. 10) Fertilizations which occur after the removal of the Zonae depend upon chance contact of the spermatozoa with the eggs. 11) If eggs are fertilized with sperm or by artificial methods after the Zonae pellucidae are removed, no fertilization membranes develope. 12) The fertilization membrane is a precipitation membrane, formed as a result of a reaction which occurrs between the out flowing fluid of the protoplasm, — after entrance of the spermatozoon into the egg or through the influence of some artificial agent, and the inner lamella of the Zona pellucida, as the latter passes into a state of solution.

On the sterile eggs of bees

On the sterile eggs of bees