Biology of Reproduction, Vol 11, 168-179, Copyright © 1974 by Society for the Study of Reproduction

Histological Changes in the Regressing Reproductive Organs of Sexually Mature Male and Female Japanese Quail

¹ Department of Anatomy, School of Veterinary Medicine, University of California, Davis, California 95616
² Department of Avian Sciences, University of California, Davis, California 95616

A reduction of daily photoperiod from 16 to 6 per 24 h induced accelerated involution (regression) of the oviducts and ovaries in sexually mature Japanese quail. Sections taken from the oviduct shortly after cessation of egg laying, when examined histologically, indicated reduced cell size of the entire surface epithelium and cessation of secretory activity in the magnum and isthmus sections. Reduction in the size and apparent degeneration of the tubular gland cells was associated with an increased proliferation of the connective tissue in the magnum, isthmus, and uterus. Massive inclusions closely associated with the tubular gland cells characterized the regressing magnum, whereas large lumina filled with cellular debris and degenerating cells were seen in the isthmus and uterus. Regressing ovarian tissue was characterized by increased connective tissue and various forms of follicular atresia although primary oocytes and small follicles remained a constant feature. Signs of involution (regression) were seen in the majority of the testes, primarily, 10 days after light reduction. Seminiferous tubules filled with necrotic debris and increased steatogenesis were features associated with testicular involution (regression). Four weeks after light reduction, the majority of the lipoidal seminiferous tubules were cleared of necrotic debris and contained essentially a single layer of germinal epithelium. These results indicate that after 4 wk of decreased photoperiod the reproductive organs of both sexes were histologically similar to the organs during the immature stages of development.