(Herrler et al., 1993; Palma et al., 1997; Prelle et al. 2001; Moreira et al., 2002b;

Sirisathien et al., 2003; Block et al., 2003), increase blastocyst cell number (Byrne et al.,

2002b; Moreira et al., 2002; Sirisathien and Brackett, 2003; Sirisathien et al., 2003b) and

glucose transport (Pantaleon and Kaye, 1996), and reduce the proportion of blastomeres

that are apoptotic (Byrne et al., 2002b; Markkula and Makarevich, 2002; Sirisathien and

Brackett, 2003). Moreover, treatment of embryos during culture with IGF-1 increases

post-transfer survival of those embryos when transferred into heat stressed, lactating

dairy cows (Block et al., 2003; Chapter 4).

 The objective of the present experiment was to determine molecular and cellular

actions of IGF-1 that could explain the increased potential for embryonic survival after

transfer (Block et al., 2003; Chapter 4). Focus was placed on effects of IGF-1 on cell

number, cell allocation, and apoptosis and the relative abundance of several

developmentally important mRNA transcripts.

 Materials and Methods

 All materials were purchased from Sigma (St. Louis, MO) or Fisher Scientific

(Fairlawn, NJ) unless specified otherwise.

Culture Media

 Sperm-Tyrode's Lactate, IVF-Tyrode's Lactate, and Hepes Tyrode's Lactate were

purchased from Caisson Laboratories, Inc. (Logan, UT). These media were used to

prepare Sperm-Tyrode's Albumin Lactate Pyruvate (TALP), IVF-TALP, and Hepes-

TALP as described previously (Parrish et al., 1986). Oocyte collection medium (OCM)

was Tissue Culture Medium-199 (TCM-199) with Hank's salts without phenol red

(Atlanta Biologicals, Norcross, GA) and supplemented with 2% (v/v) bovine steer serum

(Pel-Freez, Rogers, AR), 2 U/mL heparin, 100 U/mL penicillin-G, 0.1 mg/mL