Ontogenesis (1987)

Rotating hoop with figures of man, birds and animals inside (animation).

Schematic demonstration of ontogenesis phases (animation).

Meadow grass and flowers.

Fertilization process, union of male and female germ cells.

Penetration of sperm into egg, union of X and Y chromosomes (animation).

Thickening of egg membrane.

Union of nuclear material of egg and sperm (animation).

Formation of embryo - zygotes, division of embryo cell (animation).

Cleavage division, division of embryo into two daughter cells (animation).

Fish prepare a place for laying eggs, female lays eggs.

Male fertilizes eggs.

Newborn fry.

African clawed frog in aquarium.

Sexual intercourse of male and female clawed frogs.

Fertilized eggs laid by the female in water for further development.

The process of cleavage of a frog egg and formation of a multicellular embryo, complete division of the egg and formation of the blastula.

Conventional section and structure of the blastula (animation).

The appearance of invagination of ectoderm cells during egg gastrulation (animation).

Formation of the mesoderm (animation).

Formation of the primary mouth - blastopore - on the surface of the embryo (animation).

Scheme of movement of germ layers during gastrulation.

Dark spot of the blastopore on living material.

The process of neurulation and formation of the neural tube, with the formation of the rudiment of the spinal cord on a living example.

The process of brain development in the embryo (animation).

Stretching of the embryo in length, the occurrence of spontaneous muscle contractions.

Tadpoles on the bottom of the aquarium.

Scheme of formation of integumentary tissues, nervous system, and sense organs from ectoderm (cartoon).

Organs of vision and smell in frogs.

Scheme of development of the digestive system and lungs from endoderm (cartoon).

Scheme of formation of skeletal bones, muscles, and circulatory system in frogs from mesoderm (cartoon).

Fish and clawed frogs in an aquarium.

Stages of ontogenesis.

Tadpoles in the stage of postembryonic development.

Tadpoles searching for food.

Types of tadpoles.

Development of limbs in tadpoles.

Transformation of a tadpole into a frog.

Young frogs during the maturation of reproductive products.

Stages of postembryonic development in frogs (cartoon).

View of the edge of a spring forest, a bear crossing a clearing.

A bear cub emerges from a den.

A bear cub with a she-bear in the forest.

A beetle on a flower.

Stems and leaves of meadow grass.