15. E M B R Y O G E N E S I S in vitTO
577
did not prevent their development, but a certain proportion of C O s
was required ( 5 % in the air of the culture chamber).
The glucose of the saline solution can be replaced by mannose but
not by fructose, galactose, maltose, or lactose. But lactate, pyruvate,
or malate "allow normal growth of blastulae".
It was impossible to obtain development of mouse eggs at the twocell stage in Krebs-Ringer's solution to which glucose and albumin
were added. But in the presence of calcium lactate this same medium
was favourable to segmentation and to the formation of blastulae (this
was found in twenty-one out of fifty-two cases). The lactate probably
penetrates into the interior of the cells and stimulates cell division.
In normal conditions of segmentation in vivo the lactic acid might
be supplied by the glycolysis of the spermatozoa contained in the tubes.
Purshottam and Pincus (1961) tried to analyse with greater precision
the requirements of rabbit and mouse eggs in the course of their early
development. From the two-cell stage to the morula stage, the rabbit
and mouse eggs were able to develop for a time on Eagle's synthetic
medium, without the addition of serum. Mouse eggs developed
better in this environment than rabbit eggs. Similarly, an environment
whose composition is analogous to that provided by Whitten (KrebsRinger plus glucose plus albumin) was favourable to mouse eggs but
not to rabbit eggs. However, the conditions of development were improved by the addition of serum to the basal medium, and in particular
the addition of homologous serum. Serum was indispensable to the
growth of embryos from the bias tula stage to the blastocyst stage. But
it was not possible to obtain growth and differentiation of embryos
in any medium beyond 96 h, when they have attained the blastocyst
stage which corresponds to the moment of implantation in the uterine
mucosa.
One may conclude from these results that in the course of segmentation the egg requires a medium well equilibrated in terms of osmotic
pressure and pH, but does not need complex nutritive factors. However,
at the moment of blastocyst formation and of implantation it does
require more complex and more specific nutrients. These investigations
provide an introduction to the problem of the environmental conditions
and nutrition necessary for the development of young embryos.
C
C U L T U R E
O F U T E R I N E E G G S
A T T H E B L A S T O C Y S T
S T A G E
The first attempt to cultivate mammalian embryos was made by
Brachet (1913). He took blastodermic vesicles from the uterus of the
rabbit on the seventh day and put them in tubes containing coagulated
plasma from the rabbit. After 24-48 h, he noted the beginning of develu
577
did not prevent their development, but a certain proportion of C O s
was required ( 5 % in the air of the culture chamber).
The glucose of the saline solution can be replaced by mannose but
not by fructose, galactose, maltose, or lactose. But lactate, pyruvate,
or malate "allow normal growth of blastulae".
It was impossible to obtain development of mouse eggs at the twocell stage in Krebs-Ringer's solution to which glucose and albumin
were added. But in the presence of calcium lactate this same medium
was favourable to segmentation and to the formation of blastulae (this
was found in twenty-one out of fifty-two cases). The lactate probably
penetrates into the interior of the cells and stimulates cell division.
In normal conditions of segmentation in vivo the lactic acid might
be supplied by the glycolysis of the spermatozoa contained in the tubes.
Purshottam and Pincus (1961) tried to analyse with greater precision
the requirements of rabbit and mouse eggs in the course of their early
development. From the two-cell stage to the morula stage, the rabbit
and mouse eggs were able to develop for a time on Eagle's synthetic
medium, without the addition of serum. Mouse eggs developed
better in this environment than rabbit eggs. Similarly, an environment
whose composition is analogous to that provided by Whitten (KrebsRinger plus glucose plus albumin) was favourable to mouse eggs but
not to rabbit eggs. However, the conditions of development were improved by the addition of serum to the basal medium, and in particular
the addition of homologous serum. Serum was indispensable to the
growth of embryos from the bias tula stage to the blastocyst stage. But
it was not possible to obtain growth and differentiation of embryos
in any medium beyond 96 h, when they have attained the blastocyst
stage which corresponds to the moment of implantation in the uterine
mucosa.
One may conclude from these results that in the course of segmentation the egg requires a medium well equilibrated in terms of osmotic
pressure and pH, but does not need complex nutritive factors. However,
at the moment of blastocyst formation and of implantation it does
require more complex and more specific nutrients. These investigations
provide an introduction to the problem of the environmental conditions
and nutrition necessary for the development of young embryos.
C
C U L T U R E
O F U T E R I N E E G G S
A T T H E B L A S T O C Y S T
S T A G E
The first attempt to cultivate mammalian embryos was made by
Brachet (1913). He took blastodermic vesicles from the uterus of the
rabbit on the seventh day and put them in tubes containing coagulated
plasma from the rabbit. After 24-48 h, he noted the beginning of develu