ZP1 and in situ carcinoma: As a note, Zp2 and Zp3 glycoproteins of the zona pellucida secreted specifically by the growing oocytes appeared at 12 h in all groups, where Zp1, the third glycoprotein of the mouse zona, appeared subsequently in CTRL and CIS at 24 h but remained absent in LH and CIS + LH implying an inhibitory effect of the hormone.