The micromorphological development of the post partum corpus luteum in the ewe.

The morphological changes in the post partum corpus luteum was investigated by light microscopy on 16 ewes during the normal breeding season (March/April). The increase in luteal tissue results from hypertrophy and not from hyperplasia of the granulosa and thecal cells. Two types of lutein cells were found in the corpus luteum: a large light-staining cell and a small dark-staining cell. These might reflect the 2 extremes of a spectrum of cells in different functional states, or they might represent cell lines derived from the follicular granulosa and the thecal interna, respectively.