Common types of hydrolytic DNA damage.

Deamination of cytosine creates uracil

Depurination of guanine by hydrolysis creates apurinic deoxyribose

Deamination of 5-methylcytosine generates a natural base in DNA, thymine

TLS Online TPP Program

#Id: 7595

#Unit 5. Developmental Biology

Chemotactic compounds hormone Progesterone,  made by the cumulus cells, might trigger the release of Protein kinase A from the sperm cell membrane, & allowing it to activate the sperm-specific cation CatSper channels would facilitate the transfer of calcium ions into the sperm, where they would cause exocytosis of the acrosome

TLS Online TPP Program

#Id: 7596

#Unit 5. Developmental Biology

Mouse cumulus cells also secrete a substance, CRISP1, that attracts sperm and hyperactivates them through CatSper channels

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#Id: 7597

#Unit 5. Developmental Biology

The zona pellucida in mammals plays a role analogous to that of the vitelline envelope in invertebrates; the zona, however, is a far thicker and denser structure than the vitelline envelope

TLS Online TPP Program

#Id: 7598

#Unit 5. Developmental Biology

The mouse zona pellucida is made of three major glycoproteins—ZP1, ZP2, and ZP3

TLS Online TPP Program

#Id: 7599

#Unit 5. Developmental Biology

The human zona pellucida has four major glycoproteins— ZP1, ZP2, ZP3, and ZP4

TLS Online TPP Program

#Id: 7600

#Unit 5. Developmental Biology

The mammalian egg encounters a heterogeneous population of sperm. Some sperm have undergone the acrosome reaction in or near the cumulus, whereas others have not. The egg have pathways for accepting both types of capacitated sperm.