576
ETIENNE WOLFF
B. IJV VITRO
CULTURE BEGINNING WITH FERTILIZED EGGS
IN PROCESS OF SEGMENTATION
Numerous authors have attempted to cultivate ova, fertilized
naturally, at different stages of segmentation. The results have been
more or less successful, depending upon the species studied.
Lewis and Gregory (1929) observed the growth and the development
of rabbit ova, cultivated in a hanging drop of serum, from the moment
of fertilization to the blastocyst stage. Hammond (1949) cultivated
mouse ova in process of segmentation in a medium composed of a
saline solution added to an extract of egg-white and egg-yolk. Eggs at
the two-cell stage did not continue to develop; eggs at the eight-cell
stage (sixty-five cases) attained the blastula and blastocyst stages;
eggs at the four-cell stage behaved either like two-cell or eight-cell eggs
(seven of them did not develop, twelve did).
Wintenberger, Dauzier and Thibault (1953) experimented with
ruminants' eggs (sheep and goat), cultivated in tubes containing homologous serum and replanted morning and evening in fresh serum. The
unsegmented ova of sheep segmented, but rarely developed any further
than the six blastomeres stage. The eggs removed after the fifteen
to twenty blastomeres stage continued their segmentation and attained
the blastocyst stage after 150 h of culture.
Washburn (1951) attempted to cultivate eggs of rat, removed at
stages of one to four blastomeres, in a saline solution to which were
added different organic extracts. In some cases, he obtained one or two
further divisions.
Several of these investigations have shown the possibility of putting
fertilized eggs in store in order to reimplant them in the uteri of other
females.
Further research has been aimed at a better definition of media
favourable for segmentation and for growth of eggs. Whitten (1956)
removed tubal eggs of mice on the third day after copulation, at the
eight-blastomere stage. He cultivated them in Krebs-Ringer's solution
with glucose and bicarbonate, at a p H of 7-4, to which he added l ° / o
egg white or from 0-1-0-4% of crystallized bovine albumin. Both
media allowed the eggs to develop until the blastula stage (231 of the
235 eggs tested developed) whereas the saline solution alone does not
permit any development. No substance secreted by the tubes or extracted from eggs could improve upon or replace these albumins.
In a further work, Whitten (1957) substituted successfully for albumin
either an amino acid, such as glycine, or a simple peptide. Pure
oxygen was found toxic for ova in process of segmentation: nitrogen
ETIENNE WOLFF
B. IJV VITRO
CULTURE BEGINNING WITH FERTILIZED EGGS
IN PROCESS OF SEGMENTATION
Numerous authors have attempted to cultivate ova, fertilized
naturally, at different stages of segmentation. The results have been
more or less successful, depending upon the species studied.
Lewis and Gregory (1929) observed the growth and the development
of rabbit ova, cultivated in a hanging drop of serum, from the moment
of fertilization to the blastocyst stage. Hammond (1949) cultivated
mouse ova in process of segmentation in a medium composed of a
saline solution added to an extract of egg-white and egg-yolk. Eggs at
the two-cell stage did not continue to develop; eggs at the eight-cell
stage (sixty-five cases) attained the blastula and blastocyst stages;
eggs at the four-cell stage behaved either like two-cell or eight-cell eggs
(seven of them did not develop, twelve did).
Wintenberger, Dauzier and Thibault (1953) experimented with
ruminants' eggs (sheep and goat), cultivated in tubes containing homologous serum and replanted morning and evening in fresh serum. The
unsegmented ova of sheep segmented, but rarely developed any further
than the six blastomeres stage. The eggs removed after the fifteen
to twenty blastomeres stage continued their segmentation and attained
the blastocyst stage after 150 h of culture.
Washburn (1951) attempted to cultivate eggs of rat, removed at
stages of one to four blastomeres, in a saline solution to which were
added different organic extracts. In some cases, he obtained one or two
further divisions.
Several of these investigations have shown the possibility of putting
fertilized eggs in store in order to reimplant them in the uteri of other
females.
Further research has been aimed at a better definition of media
favourable for segmentation and for growth of eggs. Whitten (1956)
removed tubal eggs of mice on the third day after copulation, at the
eight-blastomere stage. He cultivated them in Krebs-Ringer's solution
with glucose and bicarbonate, at a p H of 7-4, to which he added l ° / o
egg white or from 0-1-0-4% of crystallized bovine albumin. Both
media allowed the eggs to develop until the blastula stage (231 of the
235 eggs tested developed) whereas the saline solution alone does not
permit any development. No substance secreted by the tubes or extracted from eggs could improve upon or replace these albumins.
In a further work, Whitten (1957) substituted successfully for albumin
either an amino acid, such as glycine, or a simple peptide. Pure
oxygen was found toxic for ova in process of segmentation: nitrogen