Age‐related changes in ovarian morphology of the South American tamarin Saguinus fuscicollis (Callitrichidae)

Abstract

The aim of this histological study was to investigate the postnatal ontogeny of the ovaries in Saguinus fuscicollis to provide a detailed knowledge of the ovarian morphology for further endocrinological studies. Gonads from 43 animals between one day and 18 years of age were investigated. Based on the available material the ovarian development is characterized by seven distinct stages. 1. Neonatal stage: Folliculogenesis is still in progress. The ovarian medulla is filled with an intraovarian rete system, which forms open connections between the rete tubules and the cords containing oocytes. 2. Infantile stage: One month after birth the ovarian cortex is mainly composed of primordial follicles and a few primary follicles at the corticomedullary border, which are separated from each other by connective tissue. At two months, folliculogenesis is nearly completed. The first secondary follicles are present. 3. Juvenile stage: In six‐month‐old females weighing 184±9.5 g, folliculogenesis has reached the stage of secondary follicles with up to six layers of granulosa cells. In females of the same age weighing 251.5±37 g, antral follicles attain a maximum diameter of 925 μmm. 4. Pubertal stage: At the age of 8–10 months, corpora lutea accessoria (CLA) begin to form from atretic antral follicles. 5. Adult stage: The ovaries of all females older than 1.2 years are filled with large patches of interstitial gland tissue (IGT). In breeding females up to 58.4%of the antral follicles are intact. In non‐breeding daughters living in the family group only 1.8%are intact, the rest are in various stages of atresia and form CLA. 6. Climacterial stage: With increasing age (8–13 years), the number of intact follicles decreases dramatically and IGT fills nearly the whole ovary. 7. Senile stage: In females older than 14 years, nearly all remaining follicles show signs of atresia.