Biology of Reproduction, Vol 19, 936-948, Copyright © 1978 by Society for the Study of Reproduction

Ovarian Interstitial Gland Tissue and Serum Progestin Levels during the First Periovulatory Period in the Mated Rabbit

¹ Department of Anatomy, The George Washington University School of Medicine and Health Sciences, Washington, D. C. 20037, and University of Wisconsin Regional Primate Research Center, Madison, Wisconsin 53706

In order to determine the morphology of the interstitial gland tissue and possibly correlate these findings with the serum levels of 20-dihydroprogesterone, mature New Zealand virgin rabbits were each assigned to 1 of 4 groups: estrous controls; 5 h; 10 h; and 2 days after mating. Data indicated that the amount of interstitial gland tissue in the ovaries varied between rabbits regardless of the group to which they were assigned. The virgin estrous rabbits generally had minimal amounts of interstitial gland tissue and low levels of serum 20-dihydroprogesterone. Ovaries of some rabbits had an abundance of interstitial gland tissue which was composed mainly of large cells and had an output of 20-dihydroprogesterone greater than those ovaries with a lesser amount of interstitial gland tissue. In those ovaries where an abundance of interstitial gland tissue was present, some morphological changes were seen between the 3 periovulatory stages which can be related to variations in 20-dihydroprogesterone. At 5 h after mating, the ovaries with large amounts of interstitial gland tissue had cells with an abundance of smooth endoplasmic reticulum and serum 20-dihydroprogesterone levels were elevated. At 10 h after mating, some follicles had ovulated and the large interstitial gland cells displayed an increase in numbers of lipid droplets which was accompanied by a decrease in 20-dihydroprogesterone. At 2 days after mating, most large interstitial gland cells had an accumulation of large lipid droplets and progestin levels continued to decrease.

Note:
ACKNOWLEDGMENTS The authors express their appreciation to Marian Thor for her technical assistance and to Elizabeth Baehler and Carole Latker for their assistance in the preparation of the manuscript. They are also grateful to Dr. H. W. Mossman for his reading of the manuscript.