Morphological Aspects in Corpus Luteum Formation in Mice

Abstract

Immediately after ovulation, in the follicular cavity, by multiplying and metaplasia of granulosa and internal sheath cells, a transient endocrine gland is formed, known as the corpus luteum (corpus luteum). Although in adult mice, ovulation occurs every 4-5 days throughout the year and important individual variations were noticed in terms of the normal estrous cycle, formation, progression and regression of corpus luteum are somewhat synchronized. This paper proposes a cytohistological study of the ovary of adult mice to capture the main morphological changes which occur in the process of organization, evolution and involution of the corpus luteum in this species. The investigations were performed on adult mouse ovaries of NMRI line, in various stages of the estrous cycle. They were fixed in 10% formalin, then were sectioned 5μ in size and were stained with Mallory trichrome method. Luteal morphology emphasizes that, after the loss of oocyte, follicular cavity shrinks due to the wrinkling of sheaths, then is filled with blood and lymph resulting initially the bleeding body (corpus hemorrhagicum). Cell differentiation takes thus place on a blood-cytolitic support, which is reabsorbed, and in the parenchyma of corpus luteum two types of luteal cells can be identified (large and small).