Hyperplasia and Hypertrophy of the Chicken (Gallus Domesticus) Oviduct During a Reproductive Cycle

The quantitative changes in hyperplasia and hypertrophy of chicken (Gallus domesticus) oviducts ranging in weight from 25 mg. to 51,000 mg. were compared throughout a reproductive cycle (developing, laying, and regressing stages). The average 3000 fold increase in dry oviduct weight from the 3-week old chick to the laying hen was attributed to a 600 fold increase in cell numbers (from 47 × 106 to 28,050 × 106) and to a 5-fold increase in dry mass per cell (from 60 pg. to 318 pg.). At the end of oviduct regression both cell numbers and cell mass decreased to 4540 × 106 and 105 pg., respectively. The relative contribution of cell numbers and cell mass was also established at various oviduct weight intervals during the reproductive cycle. There were differential growth and regression patterns for the five regions of the oviduct during a reproductive cycle. The weight, cell numbers, and cell mass in the magnum and the isthmus increased more rapidly as compared with the other oviduct regions (infundibulum, uterus, and vagina) during the developing and laying stages. A similar but opposite pattern occurred during oviduct regression.