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.

TLS Online TPP Program

#Id: 7601

#Unit 5. Developmental Biology

In one pathway, sperm that have undergone the acrosome reaction bind directly to ZP2

TLS Online TPP Program

#Id: 7602

#Unit 5. Developmental Biology

In 2nd pathway, sperm with intact acrosomes become bound to ZP3, which causes the acrosome reaction, and the sperm binding is then transferred to ZP2

TLS Online TPP Program

#Id: 7603

#Unit 5. Developmental Biology

Two important acrosomal proteins  acrosin and MMP2 (matrix metaloproteinase-2)

TLS Online TPP Program

#Id: 7604

#Unit 5. Developmental Biology

MMP2 is a protein that digests extracellular matrices (such as the zona) and may be responsible for digesting a pathway to the oocyte Acrosin bind secondarily to the zona, keeping the sperm in the channel it creates