Spermatogenesis

Fate maps

Piebaldism due to mutation in KIT gene

TS of Seminiferous tubule

Spermiation

Human sperm

Human sperm in further detail

Motile apparatus of sperm

Acrosome formation

Changes in the No of germ cells in the human ovary

Growth of oocyte in frog

Schematic representation of Xenopus oocyte maturation

Oocyte in maturing stages

Cortical action in sea urchin

Cortical action in man

Fusion of egg and sperm membranes in sea urchin and mouse

Acrosome reaction in sea urchin egg

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

Acrosome reaction in mammals

Formation of fertilization envelope

Wave of calcium release across sea urchin egg during fertilization

Comparison of Spermatogenesis and Oogenesis

Time line for the fertilization of sea urchin egg

Resting potential and Fertilization potential

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

Cell cycle of somatic and early blastomeres

Role microtubules and microfilamenta in cell division

Summary of Holoblastic and meroblastic cleavages

Holoblastic cleavage in sea cucumber

Cleavage in sea urchin

Cytoplasmic rearranement

Fate map of frog

Cleavage of a frog egg

Spiral cleavage in molluscs

Right and Left handed coiling in snail

Bilateral cleavage in tunicates

Radial and rotational cleavage, a comparison

Development of human embryo from fertilization to implantation

Compaction, cell junction formation and cavitation

Hatching of blastocyst from zona pellucida

Timing of human monozygotic twinning with relation to extraembryonic membranes

• Fate maps of different animals

Fate map of Sea urchin

Fate map of a tunicate

Formation of syncytial cables

Fate map of Fish

Sea urchin development

Discoidal Meroblastic cleavage

Meroblastic cleavage in Zebra fish

Overview of early development of selected animals

Blastula of Zebra fish

Cleavage of frog egg

Reorganization of cytoplasm in the newly 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

Ingression of primary mesenchyme cells

Axis formation in chick

Invagination of the vegetal plate

Archenteron formation in sea urchin

Gastrulation in Zebra Fish

Fate map of frog

Asymmertry of amphibian egg

Organization of secondary axis by dorsal blastopore tissue

Exp of Nieuwkoop and Nakamura

Cell movements during frog gartrulation

Cell movement during frog gastrulation

Epiboly of ectoderm

Cell movement during gastrulation in Xenopus

Early movements of frog gastrulation

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.

Types of cell movements

Cell movement in embryo of chick

Formation of blastoderm in chick

Formation of two laryered blastoderm in chick

Migration of endodermal and mesodermal cells through the primitive streak

Cell movement of P/Streak

First week of human development

Eye Development