340
G. V. LOPASHOV
AND O. G.
STROEVA
On what conditions does the normal segregation of the eye rudiment
into retina and pigment epithelium depend, its parts being equipotential
at the moment of this segregation? The first investigations of this were
also those of Dragomirov (1936, 1937, 1938, 1939, 1940). He, and later
Ikeda (1937, 1938), Mikami (1939a), and Detwiler and van Dyke (1953,
1954) showed that additional retina emerged at the site of an artificial
contact of the eye rudiment with the ear vesicle and with some other
rudiments. Proceeding from this, Dragomirov (1937, 1939) and Mikami
(1939b) went further and showed that the same appearance of retina
takes place also at the site of contact of the eye rudiment with the ectoderm. Thus the eye vesicle not only induces the formation of the lens
FIG. 4. Model of eye cup and lens thickening of a 5-5 mm long human embryo showing
invagination of the eye vesicle to form the eye cup, and the deepening of the lens pit
(after Mann, 1949).
ch.f—choroid fissure.
in the ectoderm, but the ectoderm, with which it comes into contact,
induces, in its turn, the formation of the retina in the eye vesicle. In
order to solve the problem as to whether the character of the arrangement of cell material within the rudiment at the time of eye cup formation (a thick mass in the retina, and a unicellular layer in the pigment
epithelium) was an indication of its segregation into retina and pigment
epithelium, Lopashov (1945, 1960) carried out two experiments on
Amphibians, which gave a positive answer to the question and served to
initiate further analysis of the morphogenesis of the eye.
When explanted in saline solution, the whole eye rudiment (eye
vesicle) becomes concentrated into a dense clump of cells which
differentiates always into retina only, without any additional inducing
influences. When the anterior part of the neural plate (in axolotl) is
explanted with its folds, wrapped in belly epidermis of the same stage,
eye rudiments connected with large areas of the brain become blown up
G. V. LOPASHOV
AND O. G.
STROEVA
On what conditions does the normal segregation of the eye rudiment
into retina and pigment epithelium depend, its parts being equipotential
at the moment of this segregation? The first investigations of this were
also those of Dragomirov (1936, 1937, 1938, 1939, 1940). He, and later
Ikeda (1937, 1938), Mikami (1939a), and Detwiler and van Dyke (1953,
1954) showed that additional retina emerged at the site of an artificial
contact of the eye rudiment with the ear vesicle and with some other
rudiments. Proceeding from this, Dragomirov (1937, 1939) and Mikami
(1939b) went further and showed that the same appearance of retina
takes place also at the site of contact of the eye rudiment with the ectoderm. Thus the eye vesicle not only induces the formation of the lens
FIG. 4. Model of eye cup and lens thickening of a 5-5 mm long human embryo showing
invagination of the eye vesicle to form the eye cup, and the deepening of the lens pit
(after Mann, 1949).
ch.f—choroid fissure.
in the ectoderm, but the ectoderm, with which it comes into contact,
induces, in its turn, the formation of the retina in the eye vesicle. In
order to solve the problem as to whether the character of the arrangement of cell material within the rudiment at the time of eye cup formation (a thick mass in the retina, and a unicellular layer in the pigment
epithelium) was an indication of its segregation into retina and pigment
epithelium, Lopashov (1945, 1960) carried out two experiments on
Amphibians, which gave a positive answer to the question and served to
initiate further analysis of the morphogenesis of the eye.
When explanted in saline solution, the whole eye rudiment (eye
vesicle) becomes concentrated into a dense clump of cells which
differentiates always into retina only, without any additional inducing
influences. When the anterior part of the neural plate (in axolotl) is
explanted with its folds, wrapped in belly epidermis of the same stage,
eye rudiments connected with large areas of the brain become blown up