Helen A. Padykula

Food Habits and Gastric Morphology of the Grasshopper Mouse

Behavioral and morphological adaptations associated with alimentation are described in the grasshopper mouse, Onychomys torridus longicaudus . Predatory behavior is related to the selection and utilization of food. Gastric morphology demonstrates an extensive cornified lining and a restriction of the glands to a fundic pouch. This pouch, communicating with the main lumen of the stomach through a small aperture, contains both cardiac and gastric glands. The probable evolutionary derivation of this specialized fundic area is considered.

Shifts in Uterine Stromal Cell Populations during Pregnancy and Regression

The blastocyst of primates and rodents interacts directly with the uterine stroma during implantation and placentation to establish critical functional relationships. This confrontation between tissues of two different genotypes is tolerated during normal pregnancy. This phenomenon imparts distinction on the uterine stroma and sets it apart from most stromal compartments in the maternal system, which respond forcefully to allogeneic stimuli. Yet the uterine stroma, except for decidual cells, has been relatively little studied in terms of other cell populations and the nature of the extracellular matrix (ECM).

Regeneration in the Primate Uterus

Artificial programming of the menstrual cycle in rhesus monkeys is a remarkable advance in primate uterine biology (Hodgen, 1983). Ovariectomized mature monkeys receive subcutaneous silastic implants of estradiol and progesterone that mimic the serum steroidal hormonal profile of a natural 28-day menstrual cycle. Transfer of surrogate preimplantation embryos into the ampulla of the fallopian tube during artificial cycles has resulted in successful pregnancies and birth of normal offspring. This achievement was followed by production of fertile cycles in women who had been ovariectomized or had primary ovarian failure (Lutjen et al., 1984; Navot et al., 1986). These fundamental demonstrations established that primate uterine cyclic growth depends primarily on an appropriate pattern of systemic estradiol and progesterone secretion.

Cellular and Tissue Mechanisms of Primate Uterine Endometrial Renewal: An Hypothesis

Recent advances in hormonal regulation of cyclic uterine differentiation and preimplantation biology are evident in the remarkable announcements that normal live primate newborns can be produced through artificial menstrual cycles in ovariectomized rhesus monkeys and women (1–3). Such fertile menstrual cycles are produced in rhesus monkeys by a program of insertion and removal of subcutaneous silastic implants of estradiol and progesterone that serve as effective “artificial ovaries” until the placenta takes over the maintenance of pregnancy. These tangible demonstrations provide new stimulus for experimental analysis of endometrial cell and tissue compartments in the primate (rhesus) uterus with regard to the hormonal mechanisms that control cyclic renewal.