Histochemical activity of 5-4-isomerase-3-B hydroxy steroid dehydrogenase in the ovary of the viviparous mexican lizard Sceloporus mucronatus (Reptilia: Prhynosomatidae) and interelationship with progesterone levels during pregnancy

ObjectiveTo relate the histological characteristics and histochemical Δ5−4-isomerase-3 beta hydroxy steroid dehydrogenase (Δ5−43β-HSD) activity of the corpora lutea (CL) and the atresic vitellogenic follicles (AVF) with progesterone (P4) plasma concentrations in three different times of gestation (early, medium and late) in the viviparous lizard Sceloporus mucronatus (S. mucronatus).MethodsThe histological characteristics as well as histochemical activity of Δ5−43β-HSD of the CL and AVF and their relationship with plasma P4 levels were studied during three different times of pregnancy of the viviparous lizard S. mucronatus.ResultsCorpora lutea develops during the first third of gestation. In second third, the luteal tissue reaches maturity and starts the first regressive changes. The last third of gestation was characterized by a considerably advance in the luteolysis. Activity of Δ5−43β-HSD was observed in he luteal cell mas. The activity of this enzyme were high during the first third and scantle activity was detected in the last third. Even though atresic vitellogenic follicles are found throughout the whole period of gestation, Δ5−43β-HSD activity is very low in relation with showed by CL and does not change significantly in the studied period of time. Another hand, we observed a direct relationship among the histological aspect of the corpus luteum, Δ5−43β-HSD activity and progesterone levels.ConclusionsThese observations suggests that the corpus luteum is the most important source of ovarian progesterone (P4) during pregnancy and that the participation of the AVF in the production of this hormone is little or non-existent.