This document contains information on various topics related to early embryonic development, including: - Fate mapping, which determines the developmental fate of groups of cells. - Cleavage, the rapid cell divisions that occur after fertilization. Cleavage results in blastomeres and can be holoblastic, meroblastic, or spiral. - Gastrulation, the process of forming the three germ layers through cell movements and rearrangements. Types of cell movements during gastrulation are discussed for various animals. - Axis formation and patterning the early embryo. Mechanisms like dorsalization and secondary axis formation are covered. - Early stages of development for specific animals like frogs, sea urch

1. Fate maps

4. Piebaldism due to mutation in
KIT gene

11. TS of Seminiferous tubule

12. Spermiation

13. Human sperm

14. Human sperm in further detail

15. Motile apparatus of sperm

16. Acrosome formation

17. Changes in the No of germ cells in the
human ovary

18. Growth of oocyte in frog

19. Schematic representation of Xenopus oocyte
maturation

21. Oocyte in maturing stages

24. Cortical action in sea urchin

25. Cortical action in man

26. Fusion of egg and sperm membranes in sea urchin
and mouse

28. Acrosome reaction in sea urchin
egg

29. Events leading to the formation of fertilization envelop and
the hyaline layer

30. Acrosome reaction in mammals

31. Formation of fertilization envelope

32. Wave of calcium release across sea urchin egg
during fertilization

33. Comparison of Spermatogenesis and Oogenesis

34. Time line for the fertilization of sea urchin egg

35. Resting potential and Fertilization
potential

37. Cleavage
• Cleavage is a series of rapid mitotic divisions
whereby the enormous volume of egg cytoplasm
is divided into numerous smaller nucleated cells.
These cleavage stages are called blastomeres.
One consequence of this rapid division is that
the ratio to cytoplasmic to nuclear volume gets
increasingly smaller as cleavage progresses.
The rate of cell division and the placement of
blastomeres with respect to one another is
completely under the control of proteins and
mRNAs stored in the oocyte of the mother

38. Cell cycle of somatic and early
blastomeres

39. Role microtubules and microfilamenta
in cell division

40. Summary of Holoblastic and
meroblastic cleavages

41. Holoblastic cleavage in sea cucumber

42. Cleavage in sea urchin

43. Cytoplasmic rearranement

44. Fate map of frog

45. Cleavage of a frog egg

46. Spiral cleavage in molluscs

47. Right and Left handed coiling in snail

48. Bilateral cleavage in tunicates

49. Radial and rotational cleavage,
a comparison

50. Development of human embryo from
fertilization to implantation

51. Compaction, cell junction formation
and cavitation

52. Hatching of blastocyst from zona pellucida

53. Timing of human monozygotic twinning with
relation to extraembryonic membranes

54. • Fate maps of different animals

55. Fate map of Sea urchin

56. Fate map of a tunicate

57. Formation of syncytial cables

58. Fate map of Fish

59. Sea urchin development

60. Discoidal Meroblastic cleavage

61. Meroblastic cleavage in Zebra fish

62. Overview of early development of
selected animals

63. Blastula of Zebra fish

64. Cleavage of frog egg

65. fertilized egg of frog (cortical rotation)
if we allow rotation the larva is normal, if
rotation is inhibited with UVirradiation the
embryo is featureless and vetralized if we
treat the embryo with heavy water it will
enhance microtubule formation resulting into
the formation of cyclopean eye and over
developed sucker and if we impose second
rotation with centrifugation the result is
conjoined twin

66. Ingression of primary mesenchyme cells

67. Axis formation in chick

68. Invagination of the vegetal plate

69. Archenteron formation in sea urchin

70. Gastrulation in Zebra Fish

71. Fate map of frog

74. Asymmertry of amphibian egg

75. Organization of secondary axis by dorsal
blastopore tissue

78. Exp of Nieuwkoop and
Nakamura

79. Cell movements during frog gartrulation

80. Cell movement during frog gastrulation

81. Epiboly of ectoderm

82. Cell movement during gastrulation in
Xenopus

83. Early movements of frog gastrulation

84. Gastrulation
• It is the process of highly integrated cell
and tissue movements and their
rearrangements so as to develop a three
layered embryo composed of ectoderm,
mesoderm and endoderm.

85. Types of cell movements

86. Cell movement in embryo of chick

88. Formation of blastoderm in chick

89. Formation of two laryered
blastoderm in chick

90. Migration of endodermal and mesodermal cells
through the primitive streak

91. Cell movement of P/Streak

94. First week of human development

112. Eye Development