EFFECTS OF PHOTOPERIOD ON STRUCTURE OF LAMINA PROPRIA OF THE TESTIS OF OCTODON-DEGUS

The changes occurring in the testicular lamina propria (LP) of the sea sonal breeder Octodon degus were analyzed. Four groups of animals were studied using electron microscopic procedures. The animals in group I were reproductively active, whereas those in groups II, III, and IV w ere in periods of recrudescence, regression, and resting, respectively . These changes, observed in animals maintained under laboratory light ing conditions, resembled those known to be elicited in feral populati ons by natural photoperiods. Testicular changes in each group were mon itored by calculating the gonadosomatic and spermatogenetic indexes, a nd by obtaining averages of the diameter of the seminiferous tubules a nd the height of the seminiferous epithelium. The LP of group I animal s consisted of a basal membrane formed by two to four lamellae, inner and outer acellular layers containing moderate numbers of collagenous fibrils, and single or double layers of smoothly contoured myoid cells encircled by a discontinuous lymphatic epithelium. The LP of group IV animals differed considerably from the LP of group I animals: The inn er acellular layer was enlarged, and the basal membrane appeared compo sed of a variable number of lamellae with numerous folds and indentati ons. Myoid cells were very irregular in contour and enveloped by a wel l-developed surface coating. The LPs of animals in groups II and III p ossessed relatively similar characteristics, which appeared to be inte rmediate between those of groups I and IV. The significance of these m orphological changes in the LP are discussed in relation to testicular changes induced by photoperiod and other normal or pathological proce sses. (C) 1995 Wiley-Liss, Inc.