Submission Number: ALL-4-35-23

Abstract Number: 389

ENDOMETRIAL GLANDS IN THE OVINE UTERUS ARE REQUIRED FOR PRE-IMPLANTATION CONCEPTUS SURVIVAL AND GROWTH.

C Allison Gray* ¹, Kristin M Taylor* ¹, W Shawn Ramsey ¹, Jonathon R Hill* ¹, Frank F Bartol* ², Fuller W Bazer* ¹ and Thomas E Spencer* ¹

Center for Animal Biotechnology and Genomics and Department of Animal Science, Texas A&M University, College Station, TX ¹
Department of Animal and Dairy Sciences, Auburn University, Auburn, AL ²

Abstract:
Endometrial glands are present in all mammalian uteri and produce histotroph that is hypothesized to support conceptus (embryo/fetus and placental membranes) survival, growth and development. In sheep, endometrial gland morphogenesis occurs postnatally and can be epigenetically ablated by exposure to a progestin from birth for eight weeks, thereby producing an adult uterine gland knock out (UGKO) phenotype. This study determined if pregnancy could be established and/or maintained in a uterus which lacks endometrial glands. In Study 1, UGKO ewes (n=18) were repeatedly bred at estrus (Day 0) to fertile rams. However, pregnancy was never detected on Days 25 to 35 post-mating using ultrasonagraphy. In Study 2, Day 7 hatched blastocysts from normal superovulated ewes were transferred into synchronized normal control (CX) and UGKO recipient ewes. Ultrasonography on Day 35 indicated that pregnancy was established in CX (n = 5/7), but not UGKO ewes (n=0/5). In Study 3, normal CX or UGKO ewes were bred to fertile rams, and conceptuses recovered by flushing the uterus on Day 14 post-mating. All CX ewes (n=4) possessed two filamentous conceptuses of normal (9715 mm) length. The uterine flushes from four of the UGKO ewes (n=8) possessed either a filamentous (n=1) conceptus of 82 mm or growth-retarded tubular conceptuses (n=3) of 73 mm. No conceptus was found in the uterine flush of the remaining UGKO ewes (n=4). Western blot analyses of flush proteins from CX and UGKO ewes confirmed conceptus recovery results and found that less IFN was secreted by the tubular and filamentous UGKO conceptuses as compared to those from CX ewes. Histological analyses of the uterine wall from UGKO ewes revealed a striking correlation between the number of endometrial glands present and conceptus growth and development. Uteri from bred UGKO ewes with no conceptus in the uterine flush were almost devoid of uterine glands, whereas uteri from the UGKO ewe with a filamentous conceptus had a greater number of endometrial glands than uteri from UGKO ewes with the growth retarded tubular conceptuses. Collectively, these results provide clear evidence that endometrial glands and their secretions are unequivocally required for conceptus survival, growth and development during the pre-implantation period of pregnancy. Supported by USDA Grant 98-35203-6322.

Keywords: ovine, uterus, endometrium, glands, conceptus

This abstract is being presented at: 8:00 AM in session:
Uterus/Oviduct I