Size distribution and hormonal responsiveness of dispersed XXXX luteal cells during pseudopregnancy.

@entity1420 @entity1816 @entity95 @entity1176 @entity3044
Due to the evidence for two distinct steroidogenic cell types in corpora lutea of large domestic animals, cells of the @entity95 corpus luteum were characterized with respect to cell diameters, relative abundance, steroidogenic capacity and responsiveness to hormones. Pseudopregnancy was induced in @entity95 by injection of 30-160 IU pregnant mare's serum gonadotropin (PMSG) followed in 2-4 days by an i.m. injection of 20-35 micrograms @entity1176 ( @entity1176 ). Corpora lutea were obtained 2, 5 and 9 days after injection of @entity1176 and dissociated into single cell suspensions. Suspended steroidogenic cells were incubated (2 h, 37 degrees C) in medium 199 alone or in medium containing ovine luteinizing hormone (oLH) (100 ng/ml), or @entity3044 (100 microM). Media were collected and assayed for @entity1420 content. Secretion of @entity1420 (means +/- SE, n = 4) was stimulated (p less than 0.05) by oLH on each day: Day 2 = 1.7 +/- 0.2-fold; Day 5 = 3.5 +/- 0.4-fold; and Day 9 = 3.1 +/- 0.6-fold stimulation above controls. @entity3044 also stimulated (p less than 0.05) secretion of @entity1420 by suspended luteal cells on Days 2 and 9. Microscopic examination of cell suspensions stained for @entity1816 dehydrogenase (3 beta HSD) activity provided identification of cells with steroidogenic capacity. The diameters (means +/- SE) for steroidogenic cells increased (p less than 0.05) from Days 2 to 9 (Day 2 = 15.2 +/- 0.2 micron; Day 5 = 22.4 +/- 0.4 micron; Day 9 = 28.3 +/- 1.6 micron). The large cell to small cell ratio increased from 0.01 on Day 2 to 2.03 on Day 9.(ABSTRACT TRUNCATED AT 250 WORDS)
