Contractile cells constitute the majority of atrial & ventricular tissues.

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#Id: 7594

#Unit 5. Developmental Biology

Chemotaxis oocyte and its accompanying cumulus cells secrete molecules that attract capacitated sperm toward the egg during the last stages of sperm migration

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#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

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#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

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#Id: 7598

#Unit 5. Developmental Biology

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

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#Id: 7599

#Unit 5. Developmental Biology

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