L21: Germ Cell Development and Fertilization Overview

Germ lineage

Origin of reproductive cells in mammals.

Meiosis

Cell division producing haploid gametes.

Parthenogenesis

Asexual reproduction not occurring in mammals.

Sperm-egg interactions

Necessary for successful fertilization process.

Polyspermy

Condition of multiple sperm fertilizing one egg.

Blimp-1

Repressor of somatic gene transcription in germ cells.

Primordial germ cells

Early germ cells detected by Blimp-1.

SDF-1

Chemokine guiding germ cell migration.

CXCR4

Receptor activating cell migration via SDF-1.

Hindgut endoderm

Location where germ cells enter during migration.

Genital ridge

Destination of migrating primordial germ cells.

Meiosis I

First division in meiosis, involves DNA replication.

Crossing over

Exchange of genetic material during prophase I.

Haploid gametes

Result of meiosis, containing half the chromosome number.

Oogenesis

Development of female gametes in mammals.

Spermatogenesis

Development of male gametes in mammals.

Oogonia

Proliferating female germ cells in embryonic ovary.

Primary oocyte

Female germ cell arrested in prophase of meiosis I.

Polar body

Small cell produced during oocyte meiosis.

Secondary oocyte

Oocyte arrested at metaphase of meiosis II.

Spermatogonial stem cells

Cells producing spermatocytes after sexual maturity.

Trisomy

Condition of having three copies of a chromosome.

Down syndrome

Trisomy 21, a common congenital malformation.

Edwards syndrome

Trisomy 18, associated with severe developmental issues.

Patau syndrome

Trisomy 13, leads to serious health problems.

Epigenetic changes

Modifications affecting gene expression without altering DNA.

Imprinting

Heritable epigenetic control of gene expression.

Hyaluronidase

Enzyme on sperm aiding in oocyte penetration.

Acrosome reaction

Release of enzymes for zona pellucida breakdown.

Izumo protein

Sperm protein binding to oocyte Juno protein.

Zona pellucida

Outer layer of the oocyte.

Oocyte cortical granules

Release contents to prevent polyspermy.

Ovastacin

Enzyme digesting zona protein to prevent polyspermy.

Calcium release

Triggers completion of meiosis II in oocyte.

Sperm mitochondria

Destroyed after fertilization; not inherited.

Sperm centrioles

Used for first division of zygote.

Zygote

Fertilized egg, first stage of development.